class Str

String of characters

class Str is Cool does Stringy { }

Built-in class for strings. Objects of type Str are immutable.

Methods

routine chop

multi sub    chop(Str:D --> Str:D)
multi method chop(Str:D: $chars = 1 --> Str:D)

Returns the string with $chars characters removed from the end.

routine chomp

Defined as:

multi sub    chomp(Str:D  --> Str:D)
multi method chomp(Str:D: --> Str:D)

Returns the string with a logical newline (any codepoint that has the NEWLINE property) removed from the end.

Examples:

say chomp("abc\n");       # OUTPUT: «abc␤» 
say "def\r\n".chomp;      # OUTPUT: «def␤» NOTE: \r\n is a single grapheme! 
say "foo\r".chomp;        # OUTPUT: «foo␤» 

routine lc

Defined as:

multi sub    lc(Str:D  --> Str:D)
multi method lc(Str:D: --> Str:D)

Returns a lower-case version of the string.

Examples:

lc("A"); # RESULT: «"a"» 
"A".lc;  # RESULT: «"a"» 

routine uc

multi sub    uc(Str:D  --> Str:D)
multi method uc(Str:D: --> Str:D)

Returns an uppercase version of the string.

routine fc

multi sub    fc(Str:D  --> Str:D)
multi method fc(Str:D: --> Str:D)

Does a Unicode "fold case" operation suitable for doing caseless string comparisons. (In general, the returned string is unlikely to be useful for any purpose other than comparison.)

routine tc

multi sub    tc(Str:D  --> Str:D)
multi method tc(Str:D: --> Str:D)

Does a Unicode "titlecase" operation, that is changes the first character in the string to title case, or to upper case if the character has no title case mapping

routine tclc

multi sub    tclc(Str:D  --> Str:D)
multi method tclc(Str:D: --> Str:D)

Turns the first character to title case, and all other characters to lower case

routine wordcase

multi sub    wordcase(Cool $x  --> Str)
multi sub    wordcase(Str:D $x --> Str)
multi method wordcase(Str:D: :&filter = &tclcMu :$where = True --> Str)

Returns a string in which &filter has been applied to all the words that match $where. By default, this means that the first letter of every word is capitalized, and all the other letters lowercased.

method unival

multi method unival(Str:D --> Numeric)

Returns the numeric value that the first codepoint in the invocant represents, or NaN if it's not numeric.

say '4'.unival;     # OUTPUT: «4␤» 
say '¾'.unival;     # OUTPUT: «0.75␤» 
say 'a'.unival;     # OUTPUT: «NaN␤» 

method univals

multi method univals(Str:D --> List)

Returns a list of numeric values represented by each codepoint in the invocant string, and NaN for non-numeric characters.

say "4a¾".univals;  # OUTPUT: «(4 NaN 0.75)␤» 

routine chars

multi sub    chars(Cool  $x --> Int:D)
multi sub    chars(Str:D $x --> Int:D)
multi sub    chars(str   $x --> int)
multi method chars(Str:D:   --> Int:D)

Returns the number of characters in the string in graphemes. On the JVM, this currently erroneously returns the number of codepoints instead.

method encode

multi method encode(Str:D: $encoding$nf --> Blob)

Returns a Blob which represents the original string in the given encoding and normal form. The actual return type is as specific as possible, so $str.encode('UTF-8') returns a utf8 object, $str.encode('ISO-8859-1') a buf8.

routine index

multi sub    index(Cool $sStr:D $needleCool $startpos = 0 --> Int)
multi method index(Cool $needleCool $startpos = 0 --> Int)

Searches for $needle in the string starting from $startpos. It returns the offset into the string where $needle was found, and an undefined value if it was not found.

Examples:

say index "Camelia is a butterfly""a";     # OUTPUT: «1␤» 
say index "Camelia is a butterfly""a"2;  # OUTPUT: «6␤» 
say index "Camelia is a butterfly""er";    # OUTPUT: «17␤» 
say index "Camelia is a butterfly""Camel"# OUTPUT: «0␤» 
say index "Camelia is a butterfly""Onion"# OUTPUT: «Nil␤» 
 
say index("Camelia is a butterfly""Onion").defined ?? 'OK' !! 'NOT'# OUTPUT: «NOT␤» 

routine rindex

multi sub    rindex(Str:D $haystackStr:D $needleInt $startpos = $haystack.chars --> Int)
multi method rindex(Str:D $haystack: Str:D $needleInt $startpos = $haystack.chars --> Int)

Returns the last position of $needle in $haystack not after $startpos. Returns an undefined value if $needle wasn't found.

Examples:

say rindex "Camelia is a butterfly""a";     # OUTPUT: «11␤» 
say rindex "Camelia is a butterfly""a"10# OUTPUT: «6␤» 

method indices

Defined as:

multi method indices(Str:D: Str:D $needle:$overlap --> List:D)
multi method indices(Str:D: Str:D $needleInt:D $start:$overlap --> List:D)

Searches for all occurrences of $needle in the string starting from position $start, or zero if it is not specified, and returns a List with all offsets in the string where $needle was found, or an empty list if it was not found.

If the optional parameter :overlap is specified the search continues from the index directly following the previous match, otherwise the search will continue after the previous match.

say "banana".indices("a");              # OUTPUT: «(1 3 5)␤» 
say "banana".indices("ana");            # OUTPUT: «(1)␤» 
say "banana".indices("ana":overlap);  # OUTPUT: «(1 3)␤» 
say "banana".indices("ana"2);         # OUTPUT: «(3)␤» 

method match

method match($pat:continue(:$c), :pos(:$p), :global(:$g), :overlap(:$ov), :exhaustive(:$ex), :st(:$nd), :rd(:$th), :$nth:$x --> Match)

Performs a match of the string against $pat and returns a Match object if there is a successful match, and (Any) otherwise. Matches are stored in $/. If $pat is not a Regex object, match will coerce the argument to a Str and then perform a literal match against $pat.

A number of optional named parameters can be specified, which alter how the match is performed.

The :continue adverb takes as an argument the position where the regex should start to search. If no position is specified for :c it will default to 0 unless $/ is set, in which case it defaults to $/.to.

Takes a position as an argument. Fails if regex cannot be matched from that position, unlike :continue.

Instead of searching for just one match and returning a Match object, search for every non-overlapping match and return them in a List.

Finds all matches including overlapping matches, but only returns one match from each starting position.

Finds all possible matches of a regex, including overlapping matches and matches that start at the same position.

Takes an integer as an argument and returns the nth match in the string.

Takes as an argument the number of matches to return, stopping once the specified number of matches has been reached.

Examples:

say "properly".match('perl');                     # OUTPUT: «「perl」␤» 
say "properly".match(/p.../);                     # OUTPUT: «「prop」␤» 
say "1 2 3".match([1,2,3]);                       # OUTPUT: «「1 2 3」␤» 
say "a1xa2".match(/a./:continue(2));            # OUTPUT: «「a2」␤» 
say "abracadabra".match(/ a .* a /:exhaustive);
# OUTPUT: «(「abracadabra」 「abracada」 「abraca」 「abra」 「acadabra」 「acada」 「aca」 「adabra」 「ada」 「abra」)␤» 
say 'several words here'.match(/\w+/,:global);    # OUTPUT: «(「several」 「words」 「here」)␤» 
say 'abcdef'.match(/.*/:pos(2));                # OUTPUT: «「cdef」␤» 
say "foo[bar][baz]".match(/../:1st);            # OUTPUT: «「fo」␤» 
say "foo[bar][baz]".match(/../:2nd);            # OUTPUT: «「o[」␤» 
say "foo[bar][baz]".match(/../:3rd);            # OUTPUT: «「ba」␤» 
say "foo[bar][baz]".match(/../:4th);            # OUTPUT: «「r]」␤» 
say "foo[bar][baz]bada".match('ba':x(2));       # OUTPUT: «(「ba」 「ba」)␤» 

method Numeric

Defined as:

method Numeric(Str:D: --> Numeric:D)

Coerces the string to Numeric. Fails with X::Str::Numeric if the coercion cannot be done.

Only Unicode characters with property Nd, as well as leading and trailing whitespace are allowed, with the special case of the empty string being coerced to 0. Synthetic codepoints (e.g. "7\x[308]") are forbidden.

While Nl and No characters can be used as numeric literals in the language, their conversion via Str.Numeric will fail, by design. See unival if you need to coerce such characters to Numeric.

method Int

Defined as:

method Int(Str:D: --> Int:D)

Coerces the string to Int, using the same rules as Str.Numeric.

method Bool

Defined as:

method Bool(Str:D: --> Bool:D)

Returns False if the string is empty, True otherwise.

routine parse-base

multi sub    parse-base(Str:D $numInt:D $radix --> Numeric)
multi method parse-base(Str:D $num: Int:D $radix --> Numeric)

Performs the reverse of base by converting a string with a base-$radix number to its Numeric equivalent. Will fail if radix is not in range 2..36 or of the string being parsed contains characters that are not valid for the specified base.

1337.base(32).parse-base(32).say# OUTPUT: «1337␤» 
'Perl6'.parse-base(30).say;       # OUTPUT: «20652936␤» 
'FF.DD'.parse-base(16).say;       # OUTPUT: «255.863281␤» 

See also: :16<FF> syntax for number literals

routine parse-names

sub    parse-names(Str:D $names  --> Str:D)
method parse-names(Str:D $names: --> Str:D)

Takes string with comma-separated Unicode names of characters and returns a string composed of those characters. Will fail if any of the characters' names are empty or not recognized. Whitespace around character names is ignored.

say "{parse-names 'TWO HEARTS'} Perl"# OUTPUT: «I 💕 Perl␤» 
'TWO HEARTS, BUTTERFLY'.parse-names.say# OUTPUT: «💕🦋␤» 

routine split

multi sub    split(  Str:D $delimiterStr:D $input$limit = Inf,
  :$skip-empty:$v:$k:$kv:$p --> Positional)
multi sub    split(Regex:D $delimiterStr:D $input$limit = Inf,
  :$skip-empty:$v:$k:$kv:$p --> Positional)
multi sub    split(List:D $delimitersStr:D $input$limit = Inf,
  :$skip-empty:$v:$k:$kv:$p --> Positional)
multi method split(Str:D:   Str:D $delimiter$limit = Inf,
  :$skip-empty:$v:$k:$kv:$p --> Positional)
multi method split(Str:D: Regex:D $delimiter$limit = Inf,
  :$skip-empty:$v:$k:$kv:$p --> Positional)
multi method split(Str:D: List:D $delimiters$limit = Inf,
  :$skip-empty:$v:$k:$kv:$p --> Positional)

Splits a string up into pieces based on delimiters found in the string.

If DELIMITER is a string, it is searched for literally and not treated as a regex. If DELIMITER is the empty string, it effectively returns all characters of the string separately (plus an empty string at the begin and at the end). If PATTERN is a regular expression, then that will be used to split up the string. If DELIMITERS is a list, then all of its elements will be considered a delimiter (either a string or a regular expression) to split the string on.

The optional LIMIT indicates in how many segments the string should be split, if possible. It defaults to Inf (or *, whichever way you look at it), which means "as many as possible". Note that specifying negative limits will not produce any meaningful results.

A number of optional named parameters can be specified, which alter the result being returned. The :v, :k, :kv and :p named parameters all perform a special action with regards to the delimiter found.

If specified, do not return empty strings before or after a delimiter.

Also return the delimiter. If the delimiter was a regular expression, then this will be the associated Match object. Since this stringifies as the delimiter string found, you can always assume it is the delimiter string if you're not interested in further information about that particular match.

Also return the index of the delimiter. Only makes sense if a list of delimiters was specified: in all other cases, this will be 0.

Also return both the index of the delimiter, as well as the delimiter.

Also return the index of the delimiter and the delimiter as a Pair.

Examples:

say split(";""a;b;c").perl;           # OUTPUT: «("a", "b", "c").Seq␤» 
say split(";""a;b;c":v).perl;       # OUTPUT: «("a", ";", "b", ";", "c").Seq␤» 
say split(";""a;b;c"2).perl;        # OUTPUT: «("a", "b;c").Seq␤» 
say split(";""a;b;c"2:v).perl;    # OUTPUT: «("a", ";", "b;c").Seq␤» 
say split(";""a;b;c,d").perl;         # OUTPUT: «("a", "b", "c,d").Seq␤» 
say split(/\;/"a;b;c,d").perl;        # OUTPUT: «("a", "b", "c,d").Seq␤» 
say split(<; ,>"a;b;c,d").perl;       # OUTPUT: «("a", "b", "c", "d").Seq␤» 
say split(/<[;,]>/"a;b;c,d").perl;    # OUTPUT: «("a", "b", "c", "d").Seq␤» 
say split(<; ,>"a;b;c,d":k).perl;   # OUTPUT: «("a", 0, "b", 0, "c", 1, "d").Seq␤» 
say split(<; ,>"a;b;c,d":kv).perl;  # OUTPUT: «("a", 0, ";", "b", 0, ";", "c", 1, ",", "d").Seq␤» 
 
say "".split("x").perl;                 # OUTPUT: «("",).Seq␤» 
say "".split("x":skip-empty).perl;    # OUTPUT: «().Seq␤» 
 
say "abcde".split("").perl;             # OUTPUT: «("", "a", "b", "c", "d", "e", "").Seq␤» 
say "abcde".split("",:skip-empty).perl# OUTPUT: «("a", "b", "c", "d", "e").Seq␤» 

routine comb

multi sub    comb(Str:D   $matcherStr:D $input$limit = Inf)
multi sub    comb(Regex:D $matcherStr:D $input$limit = InfBool :$match)
multi sub    comb(Int:D $sizeStr:D $input$limit = Inf)
multi method comb(Str:D $input:)
multi method comb(Str:D $input: Str:D   $matcher$limit = Inf)
multi method comb(Str:D $input: Regex:D $matcher$limit = InfBool :$match)
multi method comb(Str:D $input: Int:D $size$limit = Inf)

Searches for $matcher in $input and returns a list of all matches (as Str by default, or as Match if $match is True), limited to at most $limit matches.

If no matcher is supplied, a list of characters in the string (e.g. $matcher = rx/./) is returned.

Examples:

say "abc".comb.perl;                 # OUTPUT: «("a", "b", "c").Seq␤» 
say 'abcdefghijk'.comb(3).perl;      # OUTPUT: «("abc", "def", "ghi", "jk").Seq␤» 
say 'abcdefghijk'.comb(32).perl;   # OUTPUT: «("abc", "def").Seq␤» 
say comb(/\w/"a;b;c").perl;        # OUTPUT: «("a", "b", "c").Seq␤» 
say comb(/\N/"a;b;c").perl;        # OUTPUT: «("a", ";", "b", ";", "c").Seq␤» 
say comb(/\w/"a;b;c"2).perl;     # OUTPUT: «("a", "b").Seq␤» 
say comb(/\w\;\w/"a;b;c"2).perl# OUTPUT: «("a;b",).Seq␤» 

If the matcher is an integer value, it is considered to be a matcher that is similar to / . ** matcher /, but which is about 30x faster.

routine lines

multi sub    lines(Str:D $input$limit = Inf --> Positional)
multi method lines(Str:D $input: $limit = Inf --> Positional)

Returns a list of lines (without trailing newline characters), i.e. the same as a call to $input.comb( / ^^ \N* /, $limit ) would.

Examples:

say lines("a\nb").perl;    # OUTPUT: «("a", "b").Seq␤» 
say lines("a\nb").elems;   # OUTPUT: «2␤» 
say "a\nb".lines.elems;    # OUTPUT: «2␤» 
say "a\n".lines.elems;     # OUTPUT: «1␤» 

routine words

multi sub    words(Str:D $input$limit = Inf --> Positional)
multi method words(Str:D $input: $limit = Inf --> Positional)

Returns a list of non-whitespace bits, i.e. the same as a call to $input.comb( / \S+ /, $limit ) would.

Examples:

say "a\nb\n".words.perl;       # OUTPUT: «("a", "b").Seq␤» 
say "hello world".words.perl;  # OUTPUT: «("hello", "world").Seq␤» 
say "foo:bar".words.perl;      # OUTPUT: «("foo:bar",).Seq␤» 
say "foo:bar\tbaz".words.perl# OUTPUT: «("foo:bar", "baz").Seq␤» 

routine flip

multi sub    flip(Str:D  --> Str:D)
multi method flip(Str:D: --> Str:D)

Returns the string reversed character by character.

Examples:

"Perl".flip;  # RESULT: «lreP» 
"ABBA".flip;  # RESULT: «ABBA» 

sub sprintf

multi sub sprintfStr:D $format*@args --> Str:D)

This function is mostly identical to the C library sprintf and printf functions. The only difference between the two functions is that sprintf returns a string while the printf function writes to a file.

The $format is scanned for % characters. Any % introduces a format token. Format tokens have the following grammar:

grammar Str::SprintfFormat {
 regex format_token { '%'<index>? <precision>? <modifier>? <directive> }
 token index { \d+ '$' }
 token precision { <flags>? <vector>? <precision_count> }
 token flags { <[ \x20 + 0 \# \- ]>+ }
 token precision_count { [ <[1..9]>\d* | '*' ]? [ '.' [ \d* | '*' ] ]? }
 token vector { '*'? v }
 token modifier { < ll l h V q L > }
 token directive { < % c s d u o x e f g X E G b p n i D U O F > }
}

Directives guide the use (if any) of the arguments. When a directive (other than %) is used, it indicates how the next argument passed is to be formatted into the string to be created.

NOTE: The information below is for a fully functioning sprintf implementation which hasn't been achieved yet. Formats or features not yet implemented are marked NYI.

The directives are:

% a literal percent sign
c a character with the given codepoint
s a string
d a signed integer, in decimal
u an unsigned integer, in decimal
o an unsigned integer, in octal
x an unsigned integer, in hexadecimal
e a floating-point number, in scientific notation
f a floating-point number, in fixed decimal notation
g a floating-point number, in %e or %f notation
X like x, but using uppercase letters
E like e, but using an uppercase "E"
G like g, but with an uppercase "E" (if applicable)
b an unsigned integer, in binary

Compatibility:

i a synonym for %d
D a synonym for %ld
U a synonym for %lu
O a synonym for %lo
F a synonym for %f

Perl 5 (non-)compatibility:

n produces a runtime exception
p produces a runtime exception

Modifiers change the meaning of format directives, but are largely no-ops (the semantics are still being determined).

h interpret integer as native "short" (typically int16)
NYI l interpret integer as native "long" (typically int32 or int64)
NYI ll interpret integer as native "long long" (typically int64)
NYI L interpret integer as native "long long" (typically uint64)
NYI q interpret integer as native "quads" (typically int64 or larger)

Between the % and the format letter, you may specify several additional attributes controlling the interpretation of the format. In order, these are:

format parameter index

An explicit format parameter index, such as 2$. By default, sprintf will format the next unused argument in the list, but this allows you to take the arguments out of order:

sprintf '%2$d %1$d'1234;      # OUTPUT: «34 12␤» 
sprintf '%3$d %d %1$d'123;  # OUTPUT: «3 1 1␤» 

flags

One or more of:

space + prefix non-negative number with a space prefix non-negative number with a plus sign
0 use leading zeros, not spaces, for required padding
# ensure the leading "0" for any octal,
prefix non-zero hexadecimal with "0x" or "0X",
prefix non-zero binary with "0b" or "0B"

For example:

sprintf '<% d>',  12;   # OUTPUT: «< 12>␤» 
sprintf '<% d>',   0;   # OUTPUT: «< 0>"» 
sprintf '<% d>'-12;   # OUTPUT: «<-12>␤» 
sprintf '<%+d>',  12;   # OUTPUT: «<+12>␤» 
sprintf '<%+d>',   0;   # OUTPUT: «<+0>"» 
sprintf '<%+d>'-12;   # OUTPUT: «<-12>␤» 
sprintf '<%6s>',  12;   # OUTPUT: «<    12>␤» 
sprintf '<%-6s>'12;   # OUTPUT: «<12    >␤» 
sprintf '<%06s>'12;   # OUTPUT: «<000012>␤» 
sprintf '<%#o>',  12;   # OUTPUT: «<014>␤» 
sprintf '<%#x>',  12;   # OUTPUT: «<0xc>␤» 
sprintf '<%#X>',  12;   # OUTPUT: «<0XC>␤» 
sprintf '<%#b>',  12;   # OUTPUT: «<0b1100>␤» 
sprintf '<%#B>',  12;   # OUTPUT: «<0B1100>␤» 

When a space and a plus sign are given as the flags at once, the space is ignored:

sprintf '<%+ d>'12;   # OUTPUT: «<+12>␤» 
sprintf '<% +d>'12;   # OUTPUT: «<+12>␤» 

When the # flag and a precision are given in the %o conversion, the precision is incremented if it's necessary for the leading "0":

sprintf '<%#.5o>'0o12;     # OUTPUT: «<000012>␤» 
sprintf '<%#.5o>'0o12345;  # OUTPUT: «<012345>␤» 
sprintf '<%#.0o>'0;        # OUTPUT: «<>␤» # zero precision results in no output! 

vector flag

This flag tells Perl 6 to interpret the supplied string as a vector of integers, one for each character in the string. Perl 6 applies the format to each integer in turn, then joins the resulting strings with a separator (a dot, '.', by default). This can be useful for displaying ordinal values of characters in arbitrary strings:

  NYI sprintf "%vd""AB\x{100}";           # "65.66.256" 

You can also explicitly specify the argument number to use for the join string using something like *2$v; for example:

  NYI sprintf '%*4$vX %*4$vX %*4$vX',       # 3 IPv6 addresses 
          @addr[1..3], ":";

(minimum) width

Arguments are usually formatted to be only as wide as required to display the given value. You can override the width by putting a number here, or get the width from the next argument (with * ) or from a specified argument (e.g., with *2$):

sprintf "<%s>""a";           # OUTPUT: «<a>␤» 
sprintf "<%6s>""a";          # OUTPUT: «<     a>␤» 
sprintf "<%*s>"6"a";       # OUTPUT: «<     a>␤» 
 NYI sprintf '<%*2$s>'"a"6# "<     a>" 
sprintf "<%2s>""long";       # OUTPUT: «<long>␤» (does not truncate) 

If a field width obtained through * is negative, it has the same effect as the - flag: left-justification.

precision, or maximum width

You can specify a precision (for numeric conversions) or a maximum width (for string conversions) by specifying a . followed by a number. For floating-point formats, except g and G, this specifies how many places right of the decimal point to show (the default being 6). For example:

# these examples are subject to system-specific variation 
sprintf '<%f>'1;    # OUTPUT: «"<1.000000>"␤» 
sprintf '<%.1f>'1;  # OUTPUT: «"<1.0>"␤» 
sprintf '<%.0f>'1;  # OUTPUT: «"<1>"␤» 
sprintf '<%e>'10;   # OUTPUT: «"<1.000000e+01>"␤» 
sprintf '<%.1e>'10# OUTPUT: «"<1.0e+01>"␤» 

For "g" and "G", this specifies the maximum number of digits to show, including those prior to the decimal point and those after it; for example:

# These examples are subject to system-specific variation. 
sprintf '<%g>'1;        # OUTPUT: «<1>␤» 
sprintf '<%.10g>'1;     # OUTPUT: «<1>␤» 
sprintf '<%g>'100;      # OUTPUT: «<100>␤» 
sprintf '<%.1g>'100;    # OUTPUT: «<1e+02>␤» 
sprintf '<%.2g>'100.01# OUTPUT: «<1e+02>␤» 
sprintf '<%.5g>'100.01# OUTPUT: «<100.01>␤» 
sprintf '<%.4g>'100.01# OUTPUT: «<100>␤» 

For integer conversions, specifying a precision implies that the output of the number itself should be zero-padded to this width, where the 0 flag is ignored:

(Note that this feature currently works for unsigned integer conversions, but not for signed integer.)

NYI sprintf '<%.6d>'1;      # <000001> 
NYI sprintf '<%+.6d>'1;     # <+000001> 
NYI sprintf '<%-10.6d>'1;   # <000001    > 
NYI sprintf '<%10.6d>'1;    # <    000001> 
NYI sprintf '<%010.6d>'1;   #     000001> 
NYI sprintf '<%+10.6d>'1;   # <   +000001> 
sprintf '<%.6x>'1;         # OUTPUT: «<000001>␤» 
sprintf '<%#.6x>'1;        # OUTPUT: «<0x000001>␤» 
sprintf '<%-10.6x>'1;      # OUTPUT: «<000001    >␤» 
sprintf '<%10.6x>'1;       # OUTPUT: «<    000001>␤» 
sprintf '<%010.6x>'1;      # OUTPUT: «<    000001>␤» 
sprintf '<%#10.6x>'1;      # OUTPUT: «<  0x000001>␤» 

For string conversions, specifying a precision truncates the string to fit the specified width:

sprintf '<%.5s>'"truncated";   # OUTPUT: «<trunc>␤» 
sprintf '<%10.5s>'"truncated"# OUTPUT: «<     trunc>␤» 

You can also get the precision from the next argument using .*, or from a specified argument (e.g., with .*2$):

sprintf '<%.6x>'1;       # OUTPUT: «<000001>␤» 
sprintf '<%.*x>'61;    # OUTPUT: «<000001>␤» 
NYI sprintf '<%.*2$x>'16;  # "<000001>" 
NYI sprintf '<%6.*2$x>'14# "<  0001>" 

If a precision obtained through * is negative, it counts as having no precision at all:

sprintf '<%.*s>',  7"string";   # OUTPUT: «<string>␤» 
sprintf '<%.*s>',  3"string";   # OUTPUT: «<str>␤» 
sprintf '<%.*s>',  0"string";   # OUTPUT: «<>␤» 
sprintf '<%.*s>'-1"string";   # OUTPUT: «<string>␤» 
sprintf '<%.*d>',  10;          # OUTPUT: «<0>␤» 
sprintf '<%.*d>',  00;          # OUTPUT: «<>␤» 
sprintf '<%.*d>'-10;          # OUTPUT: «<0>␤» 

size

For numeric conversions, you can specify the size to interpret the number as using l, h, V, q, L, or ll. For integer conversions (d u o x X b i D U O), numbers are usually assumed to be whatever the default integer size is on your platform (usually 32 or 64 bits), but you can override this to use instead one of the standard C types, as supported by the compiler used to build Perl 6:

(Note: None of the following have been implemented.)

hh interpret integer as C type "char" or "unsigned char"
h interpret integer as C type "short" or "unsigned short"
j interpret integer as C type "intmax_t", only with a C99 compiler (unportable)
l interpret integer as C type "long" or "unsigned long"
q, L, or ll interpret integer as C type "long long", "unsigned long long", or "quad" (typically 64-bit integers)
t interpret integer as C type "ptrdiff_t"
z interpret integer as C type "size_t"

order of arguments

Normally, sprintf takes the next unused argument as the value to format for each format specification. If the format specification uses * to require additional arguments, these are consumed from the argument list in the order they appear in the format specification before the value to format. Where an argument is specified by an explicit index, this does not affect the normal order for the arguments, even when the explicitly specified index would have been the next argument.

So:

my $a = 5my $b = 2my $c = 'net';
sprintf "<%*.*s>"$a$b$c# OUTPUT: «<   ne>␤» 

uses $a for the width, $b for the precision, and $c as the value to format; while:

  NYI sprintf '<%*1$.*s>'$a$b;

would use $a for the width and precision and $b as the value to format.

Here are some more examples; be aware that when using an explicit index, the $ may need escaping:

 sprintf "%2\$d %d\n",      1234;     # OUTPUT: «34 12␤␤» 
 sprintf "%2\$d %d %d\n",   1234;     # OUTPUT: «34 12 34␤␤» 
 sprintf "%3\$d %d %d\n",   123456# OUTPUT: «56 12 34␤␤» 
 NYI sprintf "%2\$*3\$d %d\n",  1234,  3# " 34 12\n" 
 NYI sprintf "%*1\$.*f\n",       4,  510# "5.0000\n" 

Other examples:

 NYI sprintf "%ld a big number"4294967295;
 NYI sprintf "%%lld a bigger number"4294967296;
 sprintf('%c'97);                  # OUTPUT: «a␤» 
 sprintf("%.2f"1.969);             # OUTPUT: «1.97␤» 
 sprintf("%+.3f"3.141592);         # OUTPUT: «+3.142␤» 
 sprintf('%2$d %1$d'1234);       # OUTPUT: «34 12␤» 
 sprintf("%x"255);                 # OUTPUT: «ff␤» 

Special case: sprintf("<b>%s</b>\n", "Perl 6") will not work, but one of the following will:

sprintf Q:b "<b>%s</b>\n",  "Perl 6"# OUTPUT: «<b>Perl 6</b>␤␤» 
sprintf     "<b>\%s</b>\n""Perl 6"# OUTPUT: «<b>Perl 6</b>␤␤» 
sprintf     "<b>%s\</b>\n""Perl 6"# OUTPUT: «<b>Perl 6</b>␤␤» 

method starts-with

multi method starts-with(Str:D: Str(Cool$needle --> True:D)

Returns True if the invocant is identical to or starts with $needle.

say "Hello, World".starts-with("Hello");     # OUTPUT: «True␤» 
say "https://perl6.org/".starts-with('ftp'); # OUTPUT: «False␤» 

method ends-with

multi method ends-with(Str:D: Str(Cool$needle --> True:D)

Returns True if the invocant is identical to or ends with $needle.

say "Hello, World".ends-with('Hello');      # OUTPUT: «False␤» 
say "Hello, World".ends-with('ld');         # OUTPUT: «True␤» 

method subst

multi method subst(Str:D: $matcher$replacement*%opts)

Returns the invocant string where $matcher is replaced by $replacement (or the original string, if no match was found).

There is an in-place syntactic variant of subst spelled s/matcher/replacement/.

$matcher can be a Regex, or a literal Str. Non-Str matcher arguments of type Cool are coerced to Str for literal matching.

Literal replacement substitution

my $some-string = "Some foo";
my $another-string = $some-string.subst(/foo/"string"); # gives 'Some string' 
$some-string.=subst(/foo/"string"); # in-place substitution. $some-string is now 'Some string' 

Callable

The replacement can be a Callable in which the current Match object will be placed in the $/ variable, as well as the $_ topic variable. Using a Callable as replacement is how you can refer to any of the captures created in the regex:

# Using capture from $/ variable (the $0 is the first positional capture) 
say 'abc123defg'.subst(/(\d+)/{ " before $0 after " });
# OUTPUT: «abc before 123 after defg␤» 
 
# Using capture from $/ variable (the $<foo> is a named capture) 
say 'abc123defg'.subst(/$<foo>=\d+/{ " before $<foo> after " });
# OUTPUT: «abc before 123 after defg␤» 
 
# Using WhateverCode to operate on the Match given in $_: 
say 'abc123defg'.subst(/(\d+)/"" ~ *.flip ~ " ]");
# OUTPUT: «abc[ 321 ]defg␤» 
 
# Using a Callable to generate substitution without involving current Match: 
my $i = 41;
my $str = "The answer is secret.";
my $real-answer = $str.subst(/secret/{++$i}); # The answer to everything 

More Examples

Here are other examples of usage:

my $str = "Hey foo foo foo";
$str.subst(/foo/"bar":g); # global substitution - returns Hey bar bar bar 
 
$str.subst(/foo/"no subst":x(0)); # targeted substitution. Number of times to substitute. Returns back unmodified. 
$str.subst(/foo/"bar":x(1)); #replace just the first occurrence. 
 
$str.subst(/foo/"bar":nth(3)); # replace nth match alone. Replaces the third foo. Returns Hey foo foo bar 

The :nth adverb has readable English-looking variants:

say 'ooooo'.subst: 'o''x':1st; # OUTPUT: «xoooo␤» 
say 'ooooo'.subst: 'o''x':2nd; # OUTPUT: «oxooo␤» 
say 'ooooo'.subst: 'o''x':3rd; # OUTPUT: «ooxoo␤» 
say 'ooooo'.subst: 'o''x':4th; # OUTPUT: «oooxo␤» 

Adverbs

The following adverbs are supported

short long meaning
:g :global tries to match as often as possible
:nth(Int|Callable|Whatever) only substitute the nth match; aliases: :st, :nd, :rd, and :th
:ss :samespace preserves whitespace on substitution
:ii :samecase preserves case on substitution
:mm :samemark preserves character marks (e.g. 'ü' replaced with 'o' will result in 'ö')
:x(Int|Range|Whatever) substitute exactly $x matches

Note that only in the s/// form :ii implies :i and :ss implies :s. In the method form, the :s and :i modifiers must be added to the regex, not the subst method call.

method subst-mutate

Where subst returns the modified string and leaves the original unchanged, it is possible to mutate the original string by using subst-mutate. If the match is successful, the method returns a Match object representing the successful match; if :g (or :global) argument is used, returns a List of Match objects. If no matches happen, returns Any.

my $some-string = "Some foo";
my $match = $some-string.subst-mutate(/foo/"string");
say $some-string;  # OUTPUT: «Some string␤» 
say $match;        # OUTPUT: «「foo」␤» 
$some-string.subst-mutate(/<[oe]>/'':g); # remove every o and e, notice the :g named argument from .subst 

routine substr

multi sub    substr(Str:D $sInt:D $fromInt:D $chars = $s.chars - $from --> Str:D)
multi sub    substr(Str:D $sRange $from-to --> Str:D)
multi method substr(Str:D $s: Int:D $fromInt:D $chars = $s.chars - $from --> Str:D)
multi method substr(Str:D $s: Range $from-to --> Str:D)

Returns a part of the string, starting from the character with index $from (where the first character has index 0) and with length $chars. If a range is specified, its first and last indices are used to determine the size of the substring.

Examples:

substr("Long string"63);     # RESULT: «tri» 
substr("Long string"6);        # RESULT: «tring» 
substr("Long string"6*-1);   # RESULT: «trin» 
substr("Long string"*-3*-1); # RESULT: «in» 

method substr-eq

multi method substr-eq(Str:D:  Str(Cool$test-stringInt(Cool$from --> Bool)
multi method substr-eq(Cool:D: Str(Cool$test-stringInt(Cool$from --> Bool)

Returns True if the $test-string exactly matches the String object, starting from the given initial index $from. For example, beginning with the string "foobar", the substring "bar" will match from index 3:

my $string = "foobar";
say $string.substr-eq("bar"3);    # OUTPUT: «True␤» 

However, the substring "barz" starting from index 3 won't match even though the first three letters of the substring do match:

my $string = "foobar";
say $string.substr-eq("barz"3);   # OUTPUT: «False␤» 

Naturally, to match the entire string, one merely matches from index 0:

my $string = "foobar";
say $string.substr-eq("foobar"0); # OUTPUT: «True␤» 

Since this method is inherited from the Cool type, it also works on integers. Thus the integer 42 will match the value 342 starting from index 1:

my $integer = 342;
say $integer.substr-eq(421);      # OUTPUT: «True␤» 

As expected, one can match the entire value by starting at index 0:

my $integer = 342;
say $integer.substr-eq(3420);     # OUTPUT: «True␤» 

Also using a different value or an incorrect starting index won't match:

my $integer = 342;
say $integer.substr-eq(423);      # OUTPUT: «False␤» 
say $integer.substr-eq(73420);    # OUTPUT: «False␤» 

method substr-rw

method substr-rw($from$length?)

A version of substr that returns a Proxy functioning as a writable reference to a part of a string variable. Its first argument, $from specifies the index in the string from which a substitution should occur, and its last argument, $length specifies how many characters are to be replaced.

For example, in its method form, if one wants to take the string "abc" and replace the second character (at index 1) with the letter "z", then one does this:

my $string = "abc";
$string.substr-rw(11= "z";
$string.say;                         # OUTPUT: «azc␤» 

Note that new characters can be inserted as well:

my $string = 'azc';
$string.substr-rw(20= "-Zorro-"# insert new characters BEFORE the character at index 2 
$string.say;                         # OUTPUT: «az-Zorro-c␤» 

substr-rw also has a function form, so the above examples can also be written like so:

my $string = "abc";
substr-rw($string11= "z";
$string.say;                          # OUTPUT: «azc␤» 
substr-rw($string20= "-Zorro-";
$string.say;                          # OUTPUT: «az-Zorro-c␤» 

It is also possible to alias the writable reference returned by substr-rw for repeated operations:

my $string = "A character in the 'Flintstones' is: barney";
$string ~~ /(barney)/;
my $ref := substr-rw($string$0.from$0.to);
$string.say;
# OUTPUT: «A character in the 'Flintstones' is: barney␤» 
$ref = "fred";
$string.say;
# OUTPUT: «A character in the 'Flintstones' is: fred␤» 
$ref = "wilma";
$string.say;
# OUTPUT: «A character in the 'Flintstones' is: wilma␤» 

Notice that the start position and length of string to replace has been specified via the .from and .to methods on the Match object, $0. It is thus not necessary to count characters in order to replace a substring, hence making the code more flexible.

routine samemark

multi sub samemark(Str:D $stringStr:D $pattern --> Str:D)
method    samemark(Str:D: Str:D $pattern --> Str:D)

Returns a copy of $string with the mark/accent information for each character changed such that it matches the mark/accent of the corresponding character in $pattern. If $string is longer than $pattern, the remaining characters in $string receive the same mark/accent as the last character in $pattern. If $pattern is empty no changes will be made.

Examples:

say 'åäö'.samemark('aäo');                        # OUTPUT: «aäo␤» 
say 'åäö'.samemark('a');                          # OUTPUT: «aao␤» 
 
say samemark('Pêrl''a');                        # OUTPUT: «Perl␤» 
say samemark('aöä''');                          # OUTPUT: «aöä␤» 

method succ

method succ(Str:D --> Str:D)

Returns the string incremented by one.

String increment is "magical". It searches for the last alphanumeric sequence that is not preceded by a dot, and increments it.

'12.34'.succ;      # RESULT: «13.34» 
'img001.png'.succ# RESULT: «img002.png» 

The actual increment step works by mapping the last alphanumeric character to a character range it belongs to, and choosing the next character in that range, carrying to the previous letter on overflow.

'aa'.succ;   # RESULT: «ab» 
'az'.succ;   # RESULT: «ba» 
'109'.succ;  # RESULT: «110» 
'α'.succ;    # RESULT: «β» 
'a9'.succ;   # RESULT: «b0» 

String increment is Unicode-aware, and generally works for scripts where a character can be uniquely classified as belonging to one range of characters.

method pred

method pred(Str:D: --> Str:D)

Returns the string decremented by one.

String decrementing is "magical" just like string increment (see succ). It fails on underflow

'b0'.pred;           # RESULT: «a9» 
'a0'.pred;           # Failure 
'img002.png'.pred;   # RESULT: «img001.png» 

routine ord

multi sub    ord(Str:D  --> Int:D)
multi method ord(Str:D: --> Int:D)

Returns the codepoint number of the base characters of the first grapheme in the string.

Example:

ord("A"); # 65 
"«".ord;  # 171 

method ords

multi method ords(Str:D: --> Positional)

Returns a list of Unicode codepoint numbers that describe the codepoints making up the string.

Example:

"aå«".ords# (97 229 171) 

Strings are represented as graphemes. If a character in the string is represented by multiple codepoints, then all of those codepoints will appear in the result of ords. Therefore, the number of elements in the result may not always be equal to chars, but will be equal to codes.

The codepoints returned will represent the string in NFC. See the NFD, NFKC, and NFKD methods if other forms are required.

method trans

multi method trans(Str:D: Pair:D \what*%n --> Str)
multi method trans(Str:D: *@changes:complement(:$c), :squash(:$s), :delete(:$d--> Str)

Replaces one or many characters with one or many characters. Ranges are supported, both for keys and values. Regexes work as keys. In case a list of keys and values is used, substrings can be replaced as well. When called with :complement anything but the matched value or range is replaced with a single value. With :delete the matched characters are removed. Combining :complement and :delete will remove anything but the matched values. The adverb :squash will reduce repeated matched characters to a single character.

Example:

my $str = 'say $x<b> && $y<a>';
$str.=trans'<' => '«' );
$str.=trans'<' => '«''>' => '»' );
 
$str.=trans( [ '<'   , '>'   , '&' ] =>
             [ '&lt;''&gt;''&amp;' ]);
 
$str.=trans( ['a'..'y'=> ['A'..'z'] );
 
"abcdefghij".trans(/<[aeiou]> \w/ => '');                     # RESULT: «cdgh» 
 
"a123b123c".trans(['a'..'z'=> 'x':complement);            # RESULT: «axxxbxxxc» 
"a123b123c".trans('23' => '':delete);                       # RESULT: «a1b1c» 
"aaa1123bb123c".trans('a'..'z' => 'A'..'Z':squash);         # RESULT: «A1123B123C» 
"aaa1123bb123c".trans('a'..'z' => 'x':complement:squash); # RESULT: «aaaxbbxc» 

method indent

multi method indent(Int $steps where { $_ == 0 } )
multi method indent(Int $steps where { $_ > 0  } )
multi method indent($steps where { .isa(Whatever|| .isa(Int&& $_ < 0 } )

Indents each line of the string by $steps. If $steps is negative, it outdents instead. If $steps is *, then the string is outdented to the margin:

"  indented by 2 spaces\n    indented even more".indent(*)
    eq "indented by 2 spaces\n  indented even more"

method trim

method trim(Str:D: --> Str)

Remove leading and trailing whitespace. It can be used both as a method on strings and as a function. When used as a method it will return the trimmed string. In order to do in-place trimming, one needs to write .=trim

my $line = '   hello world    ';
say '<' ~ $line.trim ~ '>';        # OUTPUT: «<hello world>␤» 
say '<' ~ trim($line~ '>';       # OUTPUT: «<hello world>␤» 
$line.trim;
say '<' ~ $line ~ '>';             # OUTPUT: «<   hello world    >␤» 
$line.=trim;
say '<' ~ $line ~ '>';             # OUTPUT: «<hello world>␤» 

See also trim-trailing and trim-leading

method trim-trailing

method trim-trailing(Str:D: --> Str)

Remove the whitespace characters from the end of a string. See also trim.

method trim-leading

method trim-leading(Str:D: --> Str)

Remove the whitespace characters from the beginning of a string. See also trim.

method NFC

method NFC(Str:D: --> NFC:D)

Returns a codepoint string in NFC format (Unicode Normalization Form C / Composed).

method NFD

method NFD(Str:D: --> NFD:D)

Returns a codepoint string in NFD format (Unicode Normalization Form D / Decomposed).

method NFKC

method NFKC(Str:D: --> NFKC:D)

Returns a codepoint string in NFKC format (Unicode Normalization Form KC / Compatibility Composed).

method NFKD

method NFKD(Str:D: --> NFKD:D)

Returns a codepoint string in NFKD format (Unicode Normalization Form KD / Compatibility Decomposed).

method ACCEPTS

multi method ACCEPTS(Str:D: $other)

Returns True if the string is the same as $other.

sub val

multi sub val(Str:D $MAYBEVAL:$val-or-fail)

Given a Str that may be parsable as a numeric value, it will attempt to construct the appropriate allomorph, returning one of IntStr, NumStr, RatStr or ComplexStr or a plain Str if a numeric value cannot be parsed. If the :val-or-fail adverb is provided it will return an X::Str::Numeric rather than the original string if it cannot parse the string as a number.

say val("42").WHAT;    # OUTPUT: «(IntStr)␤» 
say val("42e0").WHAT;  # OUTPUT: «(NumStr)␤» 
say val("42.0").WHAT;  # OUTPUT: «(RatStr)␤» 
say val("42+0i").WHAT# OUTPUT: «(ComplexStr)␤» 

Type graph

Type relations for Str
perl6-type-graph Str Str Cool Cool Str->Cool Stringy Stringy Str->Stringy Mu Mu Any Any Any->Mu Cool->Any Numeric Numeric Complex Complex Complex->Cool Complex->Numeric ComplexStr ComplexStr ComplexStr->Str ComplexStr->Complex Real Real Real->Numeric Int Int Int->Cool Int->Real IntStr IntStr IntStr->Str IntStr->Int Rational Rational Rational->Real Rat Rat Rat->Cool Rat->Rational RatStr RatStr RatStr->Str RatStr->Rat Num Num Num->Cool Num->Real NumStr NumStr NumStr->Str NumStr->Num

Stand-alone image: vector

Routines supplied by class Cool

Str inherits from class Cool, which provides the following methods:

(Cool) routine abs

Defined as:

sub abs(Numeric() $x)
method abs()

Coerces the invocant (or in the sub form, the argument) to Numeric and returns the absolute value (that is, a non-negative number).

say (-2).abs;       # OUTPUT: «2␤» 
say abs "6+8i";     # OUTPUT: «10␤» 

(Cool) method conj

Defined as:

method conj()

Coerces the invocant to Numeric and returns the complex conjugate (that is, the number with the sign of the imaginary part negated).

say (1+2i).conj;        # OUTPUT: «1-2i␤» 

(Cool) routine sqrt

Defined as:

sub sqrt(Numeric(Cool$x)
method sqrt()

Coerces the invocant to Numeric (or in the sub form, the argument) and returns the square root, that is, a non-negative number that, when multiplied with itself, produces the original number.

say 4.sqrt;             # OUTPUT: «2␤» 
say sqrt(2);            # OUTPUT: «1.4142135623731␤» 

(Cool) method sign

Defined as:

method sign()

Coerces the invocant to Numeric and returns its sign, that is, 0 if the number is 0, 1 for positive and -1 for negative values.

say 6.sign;             # OUTPUT: «1␤» 
say (-6).sign;          # OUTPUT: «-1␤» 
say "0".sign;           # OUTPUT: «0␤» 

(Cool) method rand

Defined as:

method rand()

Coerces the invocant to Num and returns a pseudo-random value between zero and the number.

say 1e5.rand;           # OUTPUT: «33128.495184283␤» 

(Cool) routine sin

Defined as:

sub sin(Numeric(Cool))
method sin()

Coerces the invocant (or in the sub form, the argument) to Numeric, interprets it as radians, returns its sine.

say sin(0);             # OUTPUT: «0␤» 
say sin(pi/4);          # OUTPUT: «0.707106781186547␤» 
say sin(pi/2);          # OUTPUT: «1␤» 

Note that Perl 6 is no computer algebra system, so sin(pi) typically does not produce an exact 0, but rather a very small floating-point number.

(Cool) routine asin

Defined as:

sub asin(Numeric(Cool))
method asin()

Coerces the invocant (or in the sub form, the argument) to Numeric, and returns its arc-sine in radians.

say 0.1.asin;               # OUTPUT: «0.10016742116156␤» 
say asin(0.1);              # OUTPUT: «0.10016742116156␤» 

(Cool) routine cos

Defined as:

sub cos(Numeric(Cool))
method cos()

Coerces the invocant (or in sub form, the argument) to Numeric, interprets it as radians, returns its cosine.

say 0.cos;                  # OUTPUT: «1␤» 
say pi.cos;                 # OUTPUT: «-1␤» 
say cos(pi/2);              # OUTPUT: «6.12323399573677e-17␤» 

(Cool) routine acos

Defined as:

sub acos(Numeric(Cool))
method acos()

Coerces the invocant (or in sub form, the argument) to Numeric, and returns its arc-cosine in radians.

say 1.acos;                 # OUTPUT: «0␤» 
say acos(-1);               # OUTPUT: «3.14159265358979␤» 

(Cool) routine tan

Defined as:

sub tan(Numeric(Cool))
method tan()

Coerces the invocant (or in sub form, the argument) to Numeric, interprets it as radians, returns its tangent.

say tan(3);                 # OUTPUT: «-0.142546543074278␤» 
say 3.tan;                  # OUTPUT: «-0.142546543074278␤» 

(Cool) routine atan

Defined as:

sub atan(Numeric(Cool))
method atan()

Coerces the invocant (or in sub form, the argument) to Numeric, and returns its arc-tangent in radians.

say atan(3);                # OUTPUT: «1.24904577239825␤» 
say 3.atan;                 # OUTPUT: «1.24904577239825␤» 

(Cool) routine atan2

Defined as:

sub atan2(Numeric() $xNumeric() $y = 1e0)
method atan2($y = 1e0)

Coerces the arguments (including the invocant in the method form) to Numeric, and returns their two-argument arc-tangent in radians.

say atan2(3);               # OUTPUT: «1.24904577239825␤» 
say 3.atan2;                # OUTPUT: «1.24904577239825␤» 

(Cool) method sec

Defined as:

sub sec(Numeric(Cool))
method sec()

Coerces the invocant (or in sub form, its argument) to Numeric, interprets it as radians, returns its secant, that is, the reciprocal of its cosine.

say 45.sec;                 # OUTPUT: «1.90359440740442␤» 
say sec(45);                # OUTPUT: «1.90359440740442␤» 

(Cool) routine asec

Defined as:

sub asec(Numeric(Cool))
method asec()

Coerces the invocant (or in sub form, its argument) to Numeric, and returns its arc-secant in radians.

say 1.asec;                 # OUTPUT: «0␤» 
say sqrt(2).asec;           # OUTPUT: «0.785398163397448␤» 

(Cool) routine cosec

Defined as:

sub cosec(Numeric(Cool))
method cosec()

Coerces the invocant (or in sub form, its argument) to Numeric, interprets it as radians, returns its cosecant, that is, the reciprocal of its sine.

say 0.45.cosec;             # OUTPUT: «2.29903273150897␤» 
say cosec(0.45);            # OUTPUT: «2.29903273150897␤» 

(Cool) routine acosec

Defined as:

sub acosec(Numeric(Cool))
method acosec()

Coerces the invocant (or in sub form, its argument) to Numeric, and returns its arc-cosecant in radians.

say 45.acosec;              # OUTPUT: «0.0222240516182672␤» 
say acosec(45)              # OUTPUT: «0.0222240516182672␤» 

(Cool) routine cotan

Defined as:

sub cotan(Numeric(Cool))
method cotan()

Coerces the invocant (or in sub form, its argument) to Numeric, interprets it as radians, returns its cotangent, that is, the reciprocal of its tangent.

say 45.cotan;               # OUTPUT: «0.617369623783555␤» 
say cotan(45);              # OUTPUT: «0.617369623783555␤» 

(Cool) routine acotan

Defined as:

sub acotan(Numeric(Cool))
method acotan()

Coerces the invocant (or in sub form, its argument) to Numeric, and returns its arc-cotangent in radians.

say 45.acotan;              # OUTPUT: «0.0222185653267191␤» 
say acotan(45)              # OUTPUT: «0.0222185653267191␤» 

(Cool) routine sinh

Defined as:

sub sinh(Numeric(Cool))
method sinh()

Coerces the invocant (or in method form, its argument) to Numeric, and returns its Sine hyperbolicus.

say 1.sinh;                 # OUTPUT: «1.1752011936438␤» 
say sinh(1);                # OUTPUT: «1.1752011936438␤» 

(Cool) routine asinh

Defined as:

sub asinh(Numeric(Cool))
method asinh()

Coerces the invocant (or in sub form, its argument) to Numeric, and returns its Inverse Sine hyperbolicus.

say 1.asinh;                # OUTPUT: «0.881373587019543␤» 
say asinh(1);               # OUTPUT: «0.881373587019543␤» 

(Cool) routine cosh

Defined as:

sub cosh(Numeric(Cool))
method cosh()

Coerces the invocant (or in sub form, its argument) to Numeric, and returns its Cosine hyperbolicus.

say cosh(0.5);              # OUTPUT: «1.12762596520638␤» 

(Cool) routine acosh

Defined as:

sub acosh(Numeric(Cool))
method acosh()

Coerces the invocant (or in sub form, its argument) to Numeric, and returns its Inverse Cosine hyperbolicus.

say acosh(45);              # OUTPUT: «4.4996861906715␤» 

(Cool) routine tanh

Defined as:

sub tanh(Numeric(Cool))
method tanh()

Coerces the invocant (or in sub form, its argument) to Numeric, interprets it as radians and returns its Tangent hyperbolicus.

say tanh(0.5);              # OUTPUT: «0.46211715726001␤» 
say tanh(atanh(0.5));       # OUTPUT: «0.5␤» 

(Cool) routine atanh

Defined as:

sub atanh(Numeric(Cool))
method atanh()

Coerces the invocant (or in sub form, its argument) to Numeric, and returns its Inverse tangent hyperbolicus.

say atanh(0.5);             # OUTPUT: «0.549306144334055␤» 

(Cool) routine sech

Defined as:

sub sech(Numeric(Cool))
method sech()

Coerces the invocant (or in sub form, its argument) to Numeric, and returns its Secant hyperbolicus.

say 0.sech;                 # OUTPUT: «1␤» 

(Cool) routine asech

Defined as:

sub asech(Numeric(Cool))
method asech()

Coerces the invocant (or in sub form, its argument) to Numeric, and returns its Inverse hyperbolic secant.

say 0.8.asech;              # OUTPUT: «0.693147180559945␤» 

(Cool) routine cosech

Defined as:

sub cosech(Numeric(Cool))
method cosech()

Coerces the invocant (or in sub form, its argument) to Numeric, and returns its Hyperbolic cosecant.

say cosech(pi/2);           # OUTPUT: «0.434537208094696␤» 

(Cool) routine acosech

Defined as:

sub acosech(Numeric(Cool))
method acosech()

Coerces the invocant (or in sub form, its argument) to Numeric, and returns its Inverse hyperbolic cosecant.

say acosech(4.5);           # OUTPUT: «0.220432720979802␤» 

(Cool) routine cotanh

Defined as:

sub cotanh(Numeric(Cool))
method cotanh()

Coerces the invocant (or in sub form, its argument) to Numeric, and returns its Hyperbolic cotangent.

say cotanh(pi);             # OUTPUT: «1.00374187319732␤» 

(Cool) routine acotanh

Defined as:

sub acotanh(Numeric(Cool))
method acotanh()

Coerces the invocant (or in sub form, its argument) to Numeric, and returns its Inverse hyperbolic cotangent.

say acotanh(2.5);           # OUTPUT: «0.423648930193602␤» 

(Cool) routine cis

Defined as:

sub cis(Numeric(Cool))
method cis()

Coerces the invocant (or in sub form, its argument) to Numeric, and returns cos(argument) + i*sin(argument).

say cis(pi/4);              # OUTPUT: «0.707106781186548+0.707106781186547i␤» 

(Cool) routine log

Defined as:

multi sub log(Numeric(Cool$numberNumeric(Cool$base?)
multi method log(Cool:D: Cool:D $base?)

Coerces the arguments (including the invocant in the method form) to Numeric, and returns its Logarithm to base $base, or to base e (Euler's Number) if no base was supplied (Natural logarithm). Returns NaN if $base is negative. Throws an exception if $base is 1.

say (e*e).log;              # OUTPUT: «2␤» 

(Cool) routine log10

Defined as:

multi sub log10(Cool(Numeric))
multi method log10()

Coerces the invocant (or in the sub form, the invocant) to Numeric, and returns its Logarithm to base 10, that is, a number that approximately produces the original number when raised to the power of 10. Returns NaN for negative arguments and -Inf for 0.

say log10(1001);            # OUTPUT: «3.00043407747932␤» 

(Cool) method exp

Defined as:

multi sub exp(Cool:D $powCool:D $base?)
multi method exp(Cool:D: Cool:D $base?)

Coerces the arguments (including the invocant in the method from) to Numeric, and returns $base raised to the power of the first number. If no $base is supplied, e (Euler's Number) is used.

say 0.exp;      # OUTPUT: «1␤» 
say 1.exp;      # OUTPUT: «2.71828182845905␤» 
say 10.exp;     # OUTPUT: «22026.4657948067␤» 

(Cool) method unpolar

Defined as:

method unpolar(Numeric(Cool))

Coerces the arguments (including the invocant in the method form) to Numeric, and returns a complex number from the given polar coordinates. The invocant (or the first argument in sub form) is the magnitude while the argument (i.e. the second argument in sub form) is the angle. The angle is assumed to be in radians.

say sqrt(2).unpolar(pi/4);      # OUTPUT: «1+1i␤» 

(Cool) routine round

Defined as:

multi sub round(Numeric(Cool))
multi method round(Cool:D: $unit = 1)

Coerces the invocant (or in sub form, its argument) to Numeric, and rounds it to the unit of $unit. If $unit is 1, rounds to the nearest integer.

say 1.7.round;          # OUTPUT: «2␤» 
say 1.07.round(0.1);    # OUTPUT: «1.1␤» 
say 21.round(10);       # OUTPUT: «20␤» 

Always rounds up if the number is at mid-point:

say (−.5 ).round;       # OUTPUT: «0␤» 
say ( .5 ).round;       # OUTPUT: «1␤» 
say (−.55).round(.1);   # OUTPUT: «-0.5␤» 
say ( .55).round(.1);   # OUTPUT: «0.6␤» 

(Cool) routine floor

Defined as:

multi sub floor(Numeric(Cool))
multi method floor

Coerces the invocant (or in sub form, its argument) to Numeric, and rounds it downwards to the nearest integer.

say "1.99".floor;       # OUTPUT: «1␤» 
say "-1.9".floor;       # OUTPUT: «-2␤» 
say 0.floor;            # OUTPUT: «0␤» 

(Cool) routine ceiling

Defined as:

multi sub ceiling(Numeric(Cool))
multi method ceiling

Coerces the invocant (or in sub form, its argument) to Numeric, and rounds it upwards to the nearest integer.

say "1".ceiling;        # OUTPUT: «1␤» 
say "-0.9".ceiling;     # OUTPUT: «0␤» 
say "42.1".ceiling;     # OUTPUT: «43␤» 

(Cool) routine truncate

Defined as:

multi sub truncate(Numeric(Cool))
multi method truncate()

Coerces the invocant (or in sub form, its argument) to Numeric, and rounds it towards zero.

say 1.2.truncate;       # OUTPUT: «1␤» 
say truncate -1.2;      # OUTPUT: «-1␤» 

(Cool) routine ord

Defined as:

sub ord(Str(Cool))
method ord()

Coerces the invocant (or in sub form, its argument) to Str, and returns the Unicode code point number of the first code point.

say 'a'.ord;            # OUTPUT: «97␤» 

The inverse operation is chr.

Mnemonic: returns an ordinal number

(Cool) routine chr

Defined as:

sub chr(Int(Cool))
method chr()

Coerces the invocant (or in sub form, its argument) to Int, interprets it as a Unicode code points, and returns a string made of that code point.

say '65'.chr;       # OUTPUT: «A␤» 

The inverse operation is ord.

Mnemonic: turns an integer into a character.

(Cool) routine chars

Defined as:

sub chars(Str(Cool))
method chars()

Coerces the invocant (or in sub form, its argument) to Str, and returns the number of characters in the string. Please note that on the JVM, you currently get codepoints instead of graphemes.

say 'møp'.chars;    # OUTPUT: «3␤» 

(Cool) routine codes

Defined as:

sub codes(Str(Cool))
method codes()

Coerces the invocant (or in sub form, its argument) to Str, and returns the number of Unicode code points.

say 'møp'.codes;    # OUTPUT: «3␤» 

(Cool) routine flip

Defined as:

sub flip(Str(Cool))
method flip()

Coerces the invocant (or in sub form, its argument) to Str, and returns a reversed version.

say 421.flip;       # OUTPUT: «124␤» 

(Cool) routine trim

Defined as:

sub trim(Str(Cool))
method trim()

Coerces the invocant (or in sub form, its argument) to Str, and returns the string with both leading and trailing whitespace stripped.

my $stripped = '  abc '.trim;
say "<$stripped>";          # OUTPUT: «<abc>␤» 

(Cool) routine trim-leading

Defined as:

sub trim-leading(Str(Cool))
method trim-leading()

Coerces the invocant (or in sub form, its argument) to Str, and returns the string with leading whitespace stripped.

my $stripped = '  abc '.trim-leading;
say "<$stripped>";          # OUTPUT: «<abc >␤» 

(Cool) routine trim-trailing

Defined as:

sub trim-trailing(Str(Cool))
method trim-trailing()

Coerces the invocant (or in sub form, its argument) to Str, and returns the string with trailing whitespace stripped.

my $stripped = '  abc '.trim-trailing;
say "<$stripped>";          # OUTPUT: «<  abc>␤» 

(Cool) routine lc

Defined as:

sub lc(Str(Cool))
method lc()

Coerces the invocant (or in sub form, its argument) to Str, and returns it case-folded to lower case.

say "ABC".lc;       # OUTPUT: «abc␤» 

(Cool) routine uc

Defined as:

sub uc(Str(Cool))
method uc()

Coerces the invocant (or in sub form, its argument) to Str, and returns it case-folded to upper case (capital letters).

say "Abc".uc;       # OUTPUT: «ABC␤» 

(Cool) routine fc

Defined as:

sub fc(Str(Cool))
method fc()

Coerces the invocant (or in sub form, its argument) to Str, and returns the result a Unicode "case fold" operation suitable for doing caseless string comparisons. (In general, the returned string is unlikely to be useful for any purpose other than comparison.)

say "groß".fc;       # OUTPUT: «gross␤» 

(Cool) routine tc

Defined as:

sub tc(Str(Cool))
method tc()

Coerces the invocant (or in sub form, its argument) to Str, and returns it with the first letter case-folded to title case (or where not available, upper case).

say "abC".tc;       # OUTPUT: «AbC␤» 

(Cool) routine tclc

Defined as:

sub tclc(Str(Cool))
method tclc()

Coerces the invocant (or in sub form, its argument) to Str, and returns it with the first letter case-folded to title case (or where not available, upper case), and the rest of the string case-folded to lower case..

say 'abC'.tclc;     # OUTPUT: «Abc␤» 

(Cool) routine wordcase

Defined as:

sub wordcase(Str(Cool$input:&filter = &tclcMu :$where = True)
method wordcase(:&filter = &tclcMu :$where = True)

Coerces the invocant (or in sub form, the first argument) to Str, and filters each word that smart-matches against $where through the &filter. With the default filter (first character to upper case, rest to lower) and matcher (which accepts everything), this title-cases each word:

say "perl 6 programming".wordcase;      # OUTPUT: «Perl 6 Programming␤» 

With a matcher:

say "have fun working on perl".wordcase(:where({ .chars > 3 }));
                                        # Have fun Working on Perl 

With a customer filter too:

say "have fun working on perl".wordcase(:filter(&uc), :where({ .chars > 3 }));
                                        # HAVE fun WORKING on PERL 

(Cool) routine samecase

Defined as:

sub samecase(Cool $stringCool $pattern)
method samecase(Cool:D: Cool $pattern)

Coerces the invocant (or in sub form, the first argument) to Str, and returns a copy of $string with case information for each individual character changed according to $pattern. (The pattern string can contain three types of characters, i.e. uppercase, lowercase and caseless. For a given character in $pattern its case information determines the case of the corresponding character in the result.) If $string is longer than $pattern, the case information from the last character of $pattern is applied to the remaining characters of $string.

say "perL 6".samecase("A__a__"); # OUTPUT: «Perl 6␤» 
say "pERL 6".samecase("Ab");     # OUTPUT: «Perl 6␤» 

(Cool) method uniprop

Defined as:

multi sub uniprop(Str(Cool), |c)
multi sub uniprop(Int:D $codeStringy:D $propname)
multi sub uniprop(Str$codeStringy:D $propname)
multi method uniprop(|c)

Interprets the invocant as a Str, and returns the unicode property of the first character. If no property is specified returns the General Category. Returns a Bool for Boolean properties.

say 'a'.uniprop;               # OUTPUT: «Ll␤» 
say '1'.uniprop;               # OUTPUT: «Nd␤» 
say 'a'.uniprop('Alphabetic'); # OUTPUT: «True␤» 
say '1'.uniprop('Alphabetic'); # OUTPUT: «False␤» 

(Cool) method uniprops

Defined as:

sub uniprops(Str:D $strStringy:D $propname = "General_Category")

Interprets the invocant as a Str, and returns the unicode property for each character as a Seq. If no property is specified returns the General Category. Returns a Bool for Boolean properties. Similar to uniprop

(Cool) method uniname

Defined as:

sub uniname(Str(Cool--> Str)
method uniname(--> Str)

Interprets the invocant / first argument as a Str, and returns the Unicode codepoint name of the first codepoint of the first character. See uninames for a routine that works with multiple codepoints.

# Camelia in Unicode 
say »ö«.uniname;
# OUTPUT: «"RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK"␤» 
say "Ḍ̇".uniname# Note, doesn't show "COMBINING DOT ABOVE" 
# OUTPUT: «"LATIN CAPITAL LETTER D WITH DOT BELOW"␤» 
 
# Find the char with the longest Unicode name. 
say (0..0x1FFFF).sort(*.uniname.chars)[*-1].chr.uniname;
# OUTPUT: ««ARABIC LIGATURE UIGHUR KIRGHIZ YEH WITH HAMZA ABOVE WITH ALEF MAKSURA INITIAL FORM␤»␤» 

(Cool) method uninames

Defined as:

sub uninames(Str:D)
method uninames()

Returns of a Seq of Unicode names for the all the codepoints in the Str provided.

say »ö«.uninames.perl;
# OUTPUT: «("RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK", "LATIN SMALL LETTER O WITH DIAERESIS", "LEFT-POINTING DOUBLE ANGLE QUOTATION MARK").Seq␤» 

Note this example, which gets a Seq where each element is a Seq of all the codepoints in that character.

say "Ḍ̇'oh".comb>>.uninames.perl;
# OUTPUT: «(("LATIN CAPITAL LETTER D WITH DOT BELOW", "COMBINING DOT ABOVE").Seq, ("APOSTROPHE",).Seq, ("LATIN SMALL LETTER O",).Seq, ("LATIN SMALL LETTER H",).Seq)␤» 

(Cool) method unimatch

Defined as:

multi sub unimatch(Str:D $str|c)
multi unimatch(Int:D $codeStringy:D $pvalnameStringy:D $propname = $pvalname)

Checks if the given integer codepoint or the first letter of the string given have a unicode property equal to the value you give. If you supply the Unicode property to be checked it will only return True if that property matches the given value.

say unimatch 'A''Latin';           # OUTPUT: «True␤» 
say unimatch 'A''Latin''Script'# OUTPUT: «True␤» 
say unimatch 'A''Ll';              # OUTPUT: «True␤» 

(Cool) routine chop

Defined as:

sub chop(Str(Cool))
method chop()

Coerces the invocant (or in sub form, its argument) to Str, and returns it with the last character removed.

say 'perl'.chop;                        # OUTPUT: «per␤» 

(Cool) routine chomp

Defined as:

sub chomp(Str(Cool))
method chomp()

Coerces the invocant (or in sub form, its argument) to Str, and returns it with the last character removed, if it is a logical newline.

say 'ab'.chomp.chars;                   # OUTPUT: «2␤» 
say "a\n".chomp.chars;                  # OUTPUT: «1␤» 

(Cool) routine substr

Defined as:

sub substr(Str(Cool$str$from$chars?)
method substr($from$chars?)

Coerces the invocant (or in the sub form, the first argument) to Str, and returns the string starting from offset $from. If $chars is supplied, at most $chars characters are returned.

say 'zenith'.substr(2);         # OUTPUT: «nith␤» 
say 'zenith'.substr(03);      # OUTPUT: «zen␤» 
 
# works on non-strings too: 
say 20151224.substr(6);         # OUTPUT: «24␤» 
 
# sub form: 
say substr "zenith"03;      # OUTPUT: «zen␤» 

If the $from parameter is a Callable, it is called with the number of chars in the string as argument. This allows easy indexing relative to the end:

say 20151224.substr(*-2);       # OUTPUT: «24␤» 

(Cool) routine ords

Defined as:

sub ords(Str(Cool$str)
method ords()

Coerces the invocant (or in the sub form, the first argument) to Str, and returns a list of Unicode codepoints for each character.

say "Camelia".ords;              # OUTPUT: «67 97 109 101 108 105 97␤» 
say ords 10;                     # OUTPUT: «49 48␤» 

This is the list-returning version of ord. The inverse operation in chrs.

(Cool) routine chrs

Defined as:

sub chrs(*@codepoints --> Str:D)
method chrs()

Coerces the invocant (or in the sub form, the argument list) to a list of integers, and returns the string created by interpreting each integer as a Unicode codepoint, and joining the characters.

say <67 97 109 101 108 105 97>.chrs;   # OUTPUT: «Camelia␤» 

This is the list-input version of chr. The inverse operation is ords.

(Cool) routine split

Defined as:

multi sub    split(  Str:D $delimiterStr(Cool$input$limit = Inf:$k:$v:$kv:$p:$skip-empty)
multi sub    split(Regex:D $delimiterStr(Cool$input$limit = Inf:$k:$v:$kv:$p:$skip-empty)
multi sub    split(@delimitersStr(Cool$input$limit = Inf:$k:$v:$kv:$p:$skip-empty)
multi method split(  Str:D $delimiter$limit = Inf:$k:$v:$kv:$p:$skip-empty)
multi method split(Regex:D $delimiter$limit = Inf:$k:$v:$kv:$p:$skip-empty)
multi method split(@delimiters$limit = Inf:$k:$v:$kv:$p:$skip-empty)

Coerces the invocant (or in the sub form, the second argument) to Str, and splits it into pieces based on delimiters found in the string.

If $delimiter is a string, it is searched for literally and not treated as a regex. You can also provide multiple delimiters by specifying them as a list; mixing Cool and Regex objects is OK.

say split(';'"a;b;c").perl;               # OUTPUT: «("a", "b", "c")␤» 
say split(';'"a;b;c"2).perl;            # OUTPUT: «("a", "b;c").Seq␤» 
 
say split(';'"a;b;c,d").perl;             # OUTPUT: «("a", "b", "c,d")␤» 
say split(/\;/"a;b;c,d").perl;            # OUTPUT: «("a", "b", "c,d")␤» 
say split(/<[;,]>/"a;b;c,d").perl;        # OUTPUT: «("a", "b", "c", "d")␤» 
 
say split(['a', /b+/4], '1a2bb345').perl# OUTPUT: «("1", "2", "3", "5")␤» 

By default, split omits the matches, and returns a list of only those parts of the string that did not match. Specifying one of the :k, :v, :kv, :p adverbs changes that. Think of the matches as a list that is interleaved with the non-matching parts.

The :v interleaves the values of that list, which will be either Match objects, if a Regex was used as a matcher in the split, or Str objects, if a Cool was used as matcher. If multiple delimiters are specified, Match objects will be generated for all of them, unless all of the delimiters are Cool.

say 'abc'.split(/b/:v);               # OUTPUT: «(a 「b」 c)␤» 
say 'abc'.split('b':v);               # OUTPUT: «(a b c)␤» 

:k interleaves the keys, that is, the indexes:

say 'abc'.split(/b/:k);               # OUTPUT: «(a 0 c)␤» 

:kv adds both indexes and matches:

say 'abc'.split(/b/:kv);               # OUTPUT: «(a 0 「b」 c)␤» 

and :p adds them as Pairs, using the same types for values as :v does:

say 'abc'.split(/b/:p);               # OUTPUT: «(a 0 => 「b」 c)␤» 
say 'abc'.split('b':p);               # OUTPUT: «(a 0 => b c)␤» 

You can only use one of the :k, :v, :kv, :p adverbs in a single call to split.

Note that empty chunks are not removed from the result list. For that behavior, use the `:skip-empty` named argument:

say ("f,,b,c,d".split: /","/             ).perl;  # OUTPUT: «("f", "", "b", "c", "d")␤» 
say ("f,,b,c,d".split: /","/:skip-empty).perl;  # OUTPUT: «("f", "b", "c", "d")␤» 

See also: comb.

(Cool) routine lines

Defined as:

sub lines(Str(Cool))
method lines()

Coerces the invocant (and in sub form, the argument) to Str, decomposes it into lines (with the newline characters stripped), and returns the list of lines.

say lines("a\nb\n").join('|');          # OUTPUT: «a|b␤» 
say "some\nmore\nlines".lines.elems;    # OUTPUT: «3␤» 

This method can be used as part of an IO::Path to process a file line-by-line, since IO::Path objects inherit from Cool, e.g.:

for 'huge-csv'.IO.lines -> $line {
    # Do something with $line 
}
 
# or if you'll be processing later 
my @lines = 'huge-csv'.IO.lines;

Without any arguments, sub lines operates on $*ARGFILES, which defaults to $*IN in the absence of any filenames.

To modify values in place use is copy to force a writable container.

for $*IN.lines -> $_ is copy { s/(\w+)/{$0 ~ $0}/.say }

(Cool) method words

Defined as:

method words(Int() $limit)

Coerces the invocant to Str, and returns a list of words that make up the string (and if $limit is supplied, only the first $limit words).

say 'The quick brown fox'.words.join('|');      # OUTPUT: «The|quick|brown|fox␤» 
say 'The quick brown fox'.words(2).join('|');   # OUTPUT: «The|quick␤» 

Only whitespace counts as word boundaries

say "isn't, can't".words.join('|');             # OUTPUT: «isn't,|can't␤» 

(Cool) routine comb

Defined as:

multi sub comb(Regex $matcherStr(Cool$input$limit = * --> Seq)
multi method comb(Regex $matcher$limit = * --> Seq)

Returns all (or if supplied, at most $limit) matches of the invocant (method form) or the second argument (sub form) against the Regex as a list of strings.

say "6 or 12".comb(/\d+/).join("");           # OUTPUT: «6, 12␤» 

(Cool) method contains

multi method contains(Cool:D: Str(Cool$needleCool $start? --> Bool:D)

Coerces the invocant and first argument to Str, and searches for $needle in the string starting from $start. Returns True if $needle is found.

say "Hello, World".contains('Hello');      # OUTPUT: «True␤» 
say "Hello, World".contains('hello');      # OUTPUT: «False␤» 
say "Hello, World".contains(',');          # OUTPUT: «True␤» 
say "Hello, World".contains(','3);       # OUTPUT: «True␤» 
say "Hello, World".contains(','10);      # OUTPUT: «False␤» 

Note that because of how a List or Array is coerced into a Str, the results may sometimes be surprising. See traps.

(Cool) routine index

Defined as:

multi sub    index(Str(Cool$sStr:D $needleInt(Cool$startpos = 0 --> Int)
multi method index(Str(Cool$needleInt(Cool$startpos = 0 --> Int)

Coerces the first two arguments (in method form, also counting the invocant) to Str, and searches for $needle in the string starting from $startpos. It returns the offset into the string where $needle was found, and an undefined value if it was not found.

See the documentation in type Str for examples.

(Cool) routine rindex

Defined as:

multi sub    rindex(Str(Cool$haystackStr(Cool$needleInt(Cool$startpos = $haystack.chars)
multi method rindex(Str(Cool$haystack: Str(Cool$needleInt(Cool$startpos = $haystack.chars)

Coerces the first two arguments (including the invocant in method form) to Str and $startpos to Int, and returns the last position of $needle in $haystack not after $startpos. Returns an undefined value if $needle wasn't found.

See the documentation in type Str for examples.

(Cool) routine match

Defined as:

multi method match(Cool:D: $target*%adverbs)

Coerces the invocant to Str and calls the method match on it.

(Cool) method fmt

Defined as:

method fmt($format = '%s' --> Str:D)

Uses $format to return a formatted representation of the invocant.

For more information about formats strings, see sprintf.

say 11.fmt('This Int equals %03d');               # OUTPUT: «This Int equals 011␤» 
say '16'.fmt('Hexadecimal %x');                   # OUTPUT: «Hexadecimal 10␤» 

(Cool) routine roots

Defined as:

multi sub roots(Numeric(Cool$xInt(Cool$n)
multi method roots(Int(Cool$n)

Coerces the first argument (and in method form, the invocant) to Numeric and the second ($n) to Int, and produces a list of $n Complex $n-roots, which means numbers that, raised to the $nth power, approximately produce the original number.

For example

my $original = 16;
my @roots = $original.roots(4);
say @roots;
 
for @roots -> $r {
    say abs($r ** 4 - $original);
}

produces this output:

2+0i 1.22464679914735e-16+2i -2+2.44929359829471e-16i -3.67394039744206e-16-2i
1.77635683940025e-15
4.30267170434156e-15
8.03651692704705e-15
1.04441561648202e-14

(Cool) method IO

Defined as:

method IO(--> IO::Path:D)

Coerces the invocant to IO::Path.

.say for '.'.IO.dir;        # gives a directory listing 

(Cool) routine EVAL

Defined as:

sub EVAL(Cool $code:$lang = { ... })

Coerces the invocant to Str.

This works as-is with a literal string parameter. More complex input, such as a variable or string with embedded code, is illegal by default. This can be overridden in any of several ways:

use MONKEY-SEE-NO-EVAL;
use MONKEY;  # shortcut that turns on all MONKEY pragmas 
use Test;
 
# any of the above allows: 
EVAL "say { 5 + 5 }";   # OUTPUT: «10␤» 

Symbols in the current lexical scope are visible to code in an EVAL.

my $answer = 42;
EVAL 'say $answer;';    # OUTPUT: «42␤» 

However, since the set of symbols in a lexical scope is immutable after compile time, an EVAL can never introduce symbols into the surrounding scope.

EVAL 'my $lives = 9'say $lives;   # error, $lives not declared 

Furthermore, the EVAL is evaluated in the current package:

module M {
    EVAL 'our $answer = 42'
}
say $M::answer;         # OUTPUT: «42␤» 

And also the current language, meaning any added syntax is available:

sub infix:<mean>(*@ais assoc<list> {
    @a.sum / @a.elems
}
EVAL 'say 2 mean 6 mean 4';     # OUTPUT: «4␤» 

An EVAL statement evaluates to the result of the last statement:

sub infix:<mean>(*@ais assoc<list> {
    @a.sum / @a.elems
}
say EVAL 'say 1; 2 mean 6 mean 4';         # OUTPUT: «1␤4␤» 

EVAL is also a gateway for executing code in other languages:

EVAL "use v5.20; say 'Hello from perl5!'":lang<Perl5>;

(Cool) routine EVALFILE

Defined as:

sub EVALFILE(Cool $filename:$lang = { ... })

Slurps the specified file and evaluates it. Behaves the same way as EVAL with regard to both scoping and the $lang parameter. Evaluates to the value produced by the final statement in the file.

EVALFILE "foo.p6";

Routines supplied by class Any

Str inherits from class Any, which provides the following methods:

(Any) method ACCEPTS

Defined as:

multi method ACCEPTS(Any:D: Mu $other)

Usage:

EXPR.ACCEPTS(EXPR);

Returns True if $other === self (i.e. it checks object identity).

Many built-in types override this for more specific comparisons

(Any) method any

Defined as:

method any(--> Junction:D)

Interprets the invocant as a list and creates an any-Junction from it.

say so 2 == <1 2 3>.any;        # OUTPUT: «True␤» 
say so 5 == <1 2 3>.any;        # OUTPUT: «False␤» 

(Any) method all

Defined as:

method all(--> Junction:D)

Interprets the invocant as a list and creates an all-Junction from it.

say so 1 < <2 3 4>.all;         # OUTPUT: «True␤» 
say so 3 < <2 3 4>.all;         # OUTPUT: «False␤» 

(Any) method one

Defined as:

method one(--> Junction:D)

Interprets the invocant as a list and creates a one-Junction from it.

say so 1 == (123).one;      # OUTPUT: «True␤» 
say so 1 == (121).one;      # OUTPUT: «False␤» 

(Any) method none

Defined as:

method none(--> Junction:D)

Interprets the invocant as a list and creates a none-Junction from it.

say so 1 == (123).none;     # OUTPUT: «False␤» 
say so 4 == (123).none;     # OUTPUT: «True␤» 

(Any) method list

Defined as:

method list(--> List:D)

Interprets the invocant as a list, and returns that List.

say 42.list.^name;           # OUTPUT: «List␤» 
say 42.list.elems;           # OUTPUT: «1␤» 

(Any) method push

Defined as:

method push(|values --> Positional:D)

The method push is defined for undefined invocants and allows for autovivifying undefined to an empty Array, unless the undefined value implements Positional already. The argument provided will then be pushed into the newly created Array.

my %h;
dd %h<a>;      # Any (and therefore undefined) 
%h<a>.push(1); # .push on Any 
dd %h;         # «Hash %h = {:a($[1])}␤» # please note the Array 

(Any) routine reverse

Defined as:

multi sub    reverse(*@list  --> Seq:D)
multi method reverse(List:D: --> Seq:D)

Returns a Seq with the same elements in reverse order.

Note that reverse always refers to reversing elements of a list; to reverse the characters in a string, use flip.

Examples:

say <hello world!>.reverse;     # OUTPUT: «(world! hello)␤» 
say reverse ^10;                # OUTPUT: «(9 8 7 6 5 4 3 2 1 0)␤» 

(Any) method sort

Defined as:

multi method sort()
multi method sort(&custom-routine-to-use)

Sorts iterables with infix:<cmp> or given code object and returns a new List. Optionally, takes a Callable as a positional parameter, specifying how to sort.

Examples:

say <b c a>.sort;                           # OUTPUT: «(a b c)␤» 
say 'bca'.comb.sort.join;                   # OUTPUT: «abc␤» 
say 'bca'.comb.sort({$^b cmp $^a}).join;    # OUTPUT: «cba␤» 
say '231'.comb.sort(&infix:«<=>»).join;     # OUTPUT: «123␤» 

(Any) method map

Defined as:

multi method map(\SELF: &block;; :$label:$item)
multi method map(HyperIterable:D: &block;; :$label)

map will iterate over the invocant and apply the number of positional parameters of the code object from the invocant per call. The returned values of the code object will become elements of the returned Seq.

The :$label and :$item are useful only internally, since for loops get converted to maps. The :$label takes an existing Label to label the .map's loop with and :$item controls whether the iteration will occur over (SELF,) (if :$item is set) or SELF.

(Any) method deepmap

Defined as:

method deepmap(&block --> Listis nodal

deepmap will apply &block to each element and return a new List with the return values of &block, unless the element does the Iterable role. For those elements deepmap will descend recursively into the sublist.

dd [[1,2,3],[[4,5],6,7]].deepmap(*+1);
# OUTPUT: «[[2, 3, 4], [[5, 6], 7, 8]]␤» 

(Any) method duckmap

Defined as:

method duckmap(&blockis rw is nodal

duckmap will apply &block on each element and return a new list with defined return values of the block. For undefined return values, duckmap will try to descend into the element if that element implements Iterable.

<a b c d e f g>.duckmap(-> $_ where <c d e>.any { .uc }).say;
# OUTPUT: «(a b C D E f g)␤» 
(('d''e'), 'f').duckmap(-> $_ where <e f>.any { .uc }).say;
# OUTPUT: «((d E) F)␤» 

(Any) method nodemap

Defined as:

method nodemap(&block --> Listis nodal

nodemap will apply &block to each element and return a new List with the return values of &block. In contrast to deepmap it will not descend recursively into sublists if it finds elements which does the Iterable role.

say [[1,2,3], [[4,5],6,7], 7].nodemap(*+1);
# OUTPUT: «(4, 4, 8)␤» 
 
say [[23], [4, [56]]]».nodemap(*+1)
# OUTPUT: «((3 4) (5 3))␤» 

The examples above would have produced the exact same results if we had used map instead of nodemap. The difference between the two lies in the fact that map flattens out slips while nodemap doesn't.

say [[2,3], [[4,5],6,7], 7].nodemap({.elems == 1 ?? $_ !! slip});
# OUTPUT: «(() () 7)␤» 
say [[2,3], [[4,5],6,7], 7].map({.elems == 1 ?? $_ !! slip});
# OUTPUT: «(7)␤» 

(Any) method flat

Defined as:

method flat(--> Seq:Dis nodal

Interprets the invocant as a list, flattens non-containerized Iterables into a flat list, and returns that list. Keep in mind Map and Hash types are Iterable and so will be flattened into lists of pairs.

say ((12), (3), %(:42a));      # OUTPUT: «((1 2) 3 {a => 42})␤» 
say ((12), (3), %(:42a)).flat# OUTPUT: «(1 2 3 a => 42)␤» 

Note that Arrays containerize their elements by default, and so flat will not flatten them. You can use hyper method call to call .List method on all the inner Iterables and so de-containerize them, so that flat can flatten them:

say [[123], [(45), 67]]      .flat# OUTPUT: «([1 2 3] [(4 5) 6 7])␤» 
say [[123], [(45), 67]]».List.flat# OUTPUT: «(1 2 3 4 5 6 7)␤» 

For more fine-tuned options, see deepmap, duckmap, and signature destructuring

(Any) method eager

Defined as:

method eager(--> Seq:Dis nodal

Interprets the invocant as a list, evaluates it eagerly, and returns that list.

say (1..10).eager;              # OUTPUT: «(1 2 3 4 5 6 7 8 9 10)␤» 

(Any) method elems

Defined as:

method elems(--> Int:Dis nodal

Interprets the invocant as a list, and returns the number of elements in the list.

say 42.elems;                   # OUTPUT: «1␤» 
say <a b c>.elems;              # OUTPUT: «3␤» 

(Any) method end

method end(--> Any:Dis nodal

Interprets the invocant as a list, and returns the last index of that list.

say 6.end;                      # OUTPUT: «0␤» 
say <a b c>.end;                # OUTPUT: «2␤» 

(Any) method pairup

Defined as:

method pairup(--> Seq:Dis nodal

Interprets the invocant as a list, and constructs a list of pairs from it, in the same way that assignment to a Hash does. That is, it takes two consecutive elements and constructs a pair from them, unless the item in the key position already is a pair (in which case the pair is passed is passed through, and the next list item, if any, is considered to be a key again).

say (=> 1'b''c').pairup.perl;     # OUTPUT: «(:a(1), :b("c")).Seq␤» 

(Any) sub exit

Defined as:

sub exit(Int() $status = 0)

Exits the current process with return code $status.

(Any) sub item

Defined as:

proto sub item(|) is pure
multi sub item(\x)
multi sub item(|c)
multi sub item(Mu $a)

Forces given object to be evaluated in item context and returns the value of it.

say item([1,2,3]).perl;              # OUTPUT: «$[1, 2, 3]␤» 
say item({ apple => 10 }).perl;      # OUTPUT: «${:apple(10)}␤» 
say item("abc").perl;                # OUTPUT: «"abc"␤» 

You can also use $ as item contextualizer.

say $[1,2,3].perl;                   # OUTPUT: «$[1, 2, 3]␤» 
say $("abc").perl;                   # OUTPUT: «"abc"␤» 

(Any) method Array

Defined as:

method Array(--> Array:Dis nodal

Coerce the invocant to Array.

(Any) method List

Defined as:

method List(--> List:Dis nodal

Coerce the invocant to List.

(Any) method Hash

Defined as:

method Hash(--> Hash:Dis nodal

Coerce the invocant to Hash.

(Any) method hash

Defined as:

method hash(--> Hash:Dis nodal

Coerce the invocant to Hash.

(Any) method Slip

Defined as:

method Slip(--> Slip:Dis nodal

Coerce the invocant to Slip.

(Any) method Map

Defined as:

method Map(--> Map:Dis nodal

Coerce the invocant to Map.

(Any) method Bag

Defined as:

method Bag(--> Bag:Dis nodal

Coerce the invocant to Bag, whereby Positionals are treated as lists of values.

(Any) method BagHash

Defined as:

method BagHash(--> BagHash:Dis nodal

Coerce the invocant to BagHash, whereby Positionals are treated as lists of values.

(Any) method Set

Defined as:

method Set(--> Set:Dis nodal

Coerce the invocant to Set, whereby Positionals are treated as lists of values.

(Any) method SetHash

Defined as:

method SetHash(--> SetHash:Dis nodal

Coerce the invocant to SetHash, whereby Positionals are treated as lists of values.

(Any) method Mix

Defined as:

method Mix(--> Mix:Dis nodal

Coerce the invocant to Mix, whereby Positionals are treated as lists of values.

(Any) method MixHash

Defined as:

method MixHash(--> MixHash:Dis nodal

Coerce the invocant to MixHash, whereby Positionals are treated as lists of values.

(Any) method Supply

Defined as:

method Supply(--> Supply:Dis nodal

Coerce the invocant first to a List and then to a Supply.

(Any) method min

Defined As:

multi method min(--> Any:D)
multi method min(&custom-routine-to-use --> Any:D)

Coerces to Iterable and returns the numerically smallest element. If a Callable positional argument is provided it is called with each element and its smallest return values is returned.

(Any) method max

Defined As:

multi method max(--> Any:D)
multi method max(&custom-routine-to-use --> Any:D)

Coerces to Iterable and returns the numerically biggest element. If a Callable positional argument is provided it is called with each element and its biggest return values is returned.

(Any) method minmax

Defined As:

multi method minmax(--> List:D)
multi method minmax(&custom-routine-to-use --> List:D)

Returns a list containing the smallest and the biggest element. If a Callable positional argument is provided each element is filtered and then numerically compared.

(Any) method minpairs

Defined As:

multi method minpairs(Any:D: --> Seq:D)

Calls .pairs and returns a Seq with all of the Pairs with minimum values, as judged by the cmp operator:

<a b c a b c>.minpairs.perl.put# OUTPUT: «(0 => "a", 3 => "a").Seq␤» 
%(:42a, :75b).minpairs.perl.put# OUTPUT: «(:a(42),).Seq␤» 

(Any) method maxpairs

Defined As:

multi method maxpairs(Any:D: --> Seq:D)

Calls .pairs and returns a Seq with all of the Pairs with maximum values, as judged by the cmp operator:

<a b c a b c>.maxpairs.perl.put# OUTPUT: «(2 => "c", 5 => "c").Seq␤» 
%(:42a, :75b).maxpairs.perl.put# OUTPUT: «(:b(75),).Seq␤» 

(Any) method sum

Defined As:

    method sum(--> TODO)

TODO

(Any) method keys

Defined As:

    method keys(--> TODO)

TODO

(Any) method flatmap

Defined As:

    method flatmap(--> TODO)

TODO

(Any) method roll

Defined As:

    method roll(--> TODO)

TODO

(Any) method pick

Defined As:

    method pick(--> TODO)

TODO

(Any) method head

Defined As:

    method head(--> TODO)

TODO

(Any) method tail

Defined As:

    method tail(--> TODO)

TODO

(Any) method skip

Defined As:

    method skip(--> TODO)

TODO

(Any) method prepend

Defined As:

    method prepend(--> TODO)

TODO

(Any) method unshift

Defined As:

    method unshift(--> TODO)

TODO

(Any) method first

Defined As:

    method first(--> TODO)

TODO

(Any) method unique

Defined As:

    method unique

Treats the Any as a 1-item list and uses List.unique on it.

(Any) method repeated

Defined As:

    method repeated(--> TODO)

TODO

(Any) method squish

Defined As:

    method squish(--> TODO)

TODO

(Any) method reduce

Defined As:

    method reduce(--> TODO)

TODO

(Any) method permutations

Defined As:

    method permutations(--> TODO)

TODO

(Any) method categorize

Defined As:

    method categorize(--> TODO)

TODO

(Any) method classify

Defined As:

    method classify(--> TODO)

TODO

(Any) method produce

Defined As:

    method produce(--> TODO)

TODO

(Any) method rotor

Defined As:

    method rotor(--> TODO)

TODO

(Any) method pairs

Defined As:

    method pairs(--> TODO)

TODO

(Any) method antipairs

Defined As:

    method antipairs(--> TODO)

TODO

(Any) method kv

Defined As:

    method kv(--> TODO)

TODO

(Any) method tree

Defined As:

    method tree(--> TODO)

TODO

(Any) method nl-out

Defined As:

    method nl-out(--> TODO)

TODO

(Any) method invert

Defined As:

    method invert(--> TODO)

TODO

(Any) method combinations

Defined As:

    method combinations(--> TODO)

TODO

(Any) method print-nl

Defined As:

    method print-nl(--> TODO)

TODO

(Any) method iterator

Defined As:

    method iterator(--> TODO)

TODO

(Any) method grep

Defined As:

    method grep(--> TODO)

TODO

(Any) method match

Defined As:

    method match(--> TODO)

TODO

(Any) method append

Defined As:

    method append(--> TODO)

TODO

(Any) method join

Defined As:

    method join(--> TODO)

TODO

(Any) method values

Defined As:

    method values(--> TODO)

TODO

(Any) method collate

Defined As:

    method collate(--> TODO)

TODO

(Any) method batch

Defined As:

    method batch(--> TODO)

TODO

(Any) method cache

Defined As:

    method cache(--> TODO)

TODO

Routines supplied by class Mu

Str inherits from class Mu, which provides the following methods:

(Mu) routine defined

multi sub    defined(Mu --> Bool:D)
multi method defined(   --> Bool:D)

Returns False on the type object, and True otherwise.

say Int.defined;                # OUTPUT: «False␤» 
say 42.defined;                 # OUTPUT: «True␤» 

Very few types (like Failure) override defined to return False even for instances:

sub fails() { fail 'oh noe' };
say fails().defined;            # OUTPUT: «False␤» 

(Mu) routine isa

multi method isa(Mu $type     --> Bool:D)
multi method isa(Str:D $type  --> Bool:D)

Returns True if the invocant is an instance of class $type, a subset type or a derived class (through inheritance) of $type.

my $i = 17;
say $i.isa("Int");   # OUTPUT: «True␤» 
say $i.isa(Any);     # OUTPUT: «True␤» 

A more idiomatic way to do this is to use the smartmatch operator ~~ instead.

my $s = "String";
say $s ~~ Str;       # OUTPUT: «True␤» 

(Mu) routine does

method does(Mu $type --> Bool:D)

Returns True if and only if the invocant conforms to type $type.

my $d = Date.new('2016-06-03');
say $d.does(Dateish);             # True    (Date does role Dateish) 
say $d.does(Any);                 # True    (Date is a subclass of Any) 
say $d.does(DateTime);            # False   (Date is not a subclass of DateTime) 

Using the smart match operator ~~ is a more idiomatic alternative.

my $d = Date.new('2016-06-03');
say $d ~~ Dateish;                # OUTPUT: «True␤» 
say $d ~~ Any;                    # OUTPUT: «True␤» 
say $d ~~ DateTime;               # OUTPUT: «False␤» 

(Mu) routine Bool

multi sub    Bool(Mu --> Bool:D)
multi method Bool(   --> Bool:D)

Returns False on the type object, and True otherwise.

Many built-in types override this to be False for empty collections, the empty string or numerical zeros

say Mu.Bool;                    # OUTPUT: «False␤» 
say Mu.new.Bool;                # OUTPUT: «True␤» 
say [123].Bool;             # OUTPUT: «True␤» 
say [].Bool;                    # OUTPUT: «False␤» 
say { 'hash' => 'full' }.Bool;  # OUTPUT: «True␤» 
say {}.Bool;                    # OUTPUT: «False␤» 
say "".Bool;                    # OUTPUT: «False␤» 
say 0.Bool;                     # OUTPUT: «False␤» 
say 1.Bool;                     # OUTPUT: «True␤» 
say "0".Bool;                   # OUTPUT: «True␤» 

(Mu) method Capture

Defined as:

method Capture(Mu:D: --> Capture:D)

Returns a Capture with named arguments corresponding to invocant's public attributes:

class Foo {
    has $.foo = 42;
    has $.bar = 70;
    method bar { 'something else' }
}.new.Capture.say# OUTPUT: «\(:bar("something else"), :foo(42))␤» 

(Mu) method Str

multi method Str(--> Str)

Returns a string representation of the invocant, intended to be machine readable. Method Str warns on type objects, and produces the empty string.

say Mu.Str;                     # Use of uninitialized value of type Mu in string context. 

(Mu) routine gist

multi sub    gist(+args --> Str)
multi method gist(   --> Str)

Returns a string representation of the invocant, optimized for fast recognition by humans. As such lists will be truncated at 100 elements. Use .perl to get all elements.

The default gist method in Mu re-dispatches to the perl method for defined invocants, and returns the type name in parenthesis for type object invocants. Many built-in classes override the case of instances to something more specific that may truncate output.

gist is the method that say calls implicitly, for non-Str types, so say $something and say $something.gist generally produce the same output.

say Mu.gist;        # OUTPUT: «(Mu)␤» 
say Mu.new.gist;    # OUTPUT: «Mu.new␤» 

(Mu) routine perl

multi sub    perl(Mu --> Str)
multi method perl(   --> Str)

Returns a Perlish representation of the object (i.e., can usually be re-evaluated with EVAL to regenerate the object). The exact output of perl is implementation specific, since there are generally many ways to write a Perl expression that produces a particular value

(Mu) method item

method item(Mu \item:is raw

Forces the invocant to be evaluated in item context and returns the value of it.

say [1,2,3].item.perl;         # OUTPUT: «$[1, 2, 3]␤» 
say { apple => 10 }.item.perl# OUTPUT: «${:apple(10)}␤» 
say "abc".item.perl;           # OUTPUT: «"abc"␤» 

(Mu) method self

method self(--> Mu)

Returns the object it is called on.

(Mu) method clone

method clone(*%twiddles)

Creates a shallow clone of the invocant. Alternative values for public attributes can be provided via named arguments with names matching the attributes' names.

class Point2D {
    has ($.x$.y);
    multi method gist(Point2D:D:{
        "Point($.x$.y)";
    }
}
 
my $p = Point2D.new(x => 2=> 3);
 
say $p;                     # OUTPUT: «Point(2, 3)␤» 
say $p.clone(=> -5);      # OUTPUT: «Point(2, -5)␤» 

(Mu) method new

multi method new(*%attrinit)

Default method for constructing (create + initialize) new objects of a class. This method expects only named arguments which are then used to initialize attributes with accessors of the same name.

Classes may provide their own new method to override this default.

new triggers an object construction mechanism that calls submethods named BUILD in each class of an inheritance hierarchy, if they exist. See the documentation on object construction for more information.

(Mu) method bless

method bless(*%attrinit --> Mu:D)

Lower-level object construction method than new.

Creates a new object of the same type as the invocant, uses the named arguments to initialize attributes, and returns the created object.

You can use this method when writing custom constructors:

class Point {
    has $.x;
    has $.y;
    multi method new($x$y{
        self.bless(:$x:$y);
    }
}
my $p = Point.new(-11);

(Though each time you write a custom constructor, remember that it makes subclassing harder).

(Mu) method CREATE

method CREATE(--> Mu:D)

Allocates a new object of the same type as the invocant, without initializing any attributes.

say Mu.CREATE.defined;  # OUTPUT: «True␤» 

(Mu) method print

multi method print(--> Bool:D)

Prints value to $*OUT after stringification using .Str method without adding a newline at end.

"abc\n".print;          # RESULT: «abc␤» 

(Mu) method put

multi method put(--> Bool:D)

Prints value to $*OUT, adding a newline at end, and if necessary, stringifying non-Str object using the .Str method.

"abc".put;              # RESULT: «abc␤» 

(Mu) method say

multi method say(--> Bool:D)

Prints value to $*OUT after stringification using .gist method with newline at end. To produce machine readable output use .put.

say 42;                 # OUTPUT: «42␤» 

(Mu) method ACCEPTS

multi method ACCEPTS(Mu:U: $other)

ACCEPTS is the method that smart matching with the infix ~~ operator and given/when invokes on the right-hand side (the matcher).

The Mu:U multi performs a type check. Returns True if $other conforms to the invocant (which is always a type object or failure).

say 42 ~~ Mu;           # OUTPUT: «True␤» 
say 42 ~~ Int;          # OUTPUT: «True␤» 
say 42 ~~ Str;          # OUTPUT: «False␤» 

Note that there is no multi for defined invocants; this is to allow autothreading of junctions, which happens as a fallback mechanism when no direct candidate is available to dispatch to.

(Mu) method WHICH

multi method WHICH(--> ObjAt:D)

Returns an object of type ObjAt which uniquely identifies the object. Value types override this method which makes sure that two equivalent objects return the same return value from WHICH.

say 42.WHICH eq 42.WHICH;       # OUTPUT: «True␤» 

(Mu) method WHERE

method WHERE(--> Int)

Returns an Int representing the memory address of the object.

(Mu) method WHY

multi method WHY()

Returns the attached Pod value. For instance,

sub cast(Spell $s)
#= Initiate a specified spell normally 
#= (do not use for class 7 spells) 
{
do-raw-magic($s);
}
say &cast.WHY;

prints

Initiate a specified spell normally (do not use for class 7 spells)

See the documentation specification for details about attaching Pod to variables, classes, functions, methods, etc.

(Mu) trait is export

multi sub trait_mod:<is>(Mu:U \type:$export!)

Marks a type as being exported, that is, available to external users.

my class SomeClass is export { }

A user of a module or class automatically gets all the symbols imported that are marked as is export.

See Exporting and Selective Importing Modules for more details.

(Mu) method return

method return()

The method return will stop execution of a subroutine or method, run all relevant phasers and provide invocant as a return value to the caller. If a return type constraint is provided it will be checked unless the return value is Nil. A control exception is raised and can be caught with CONTROL.

sub f { (1|2|3).return };
dd f(); # OUTPUT: «any(1, 2, 3)␤» 

(Mu) method return-rw

Same as method return except that return-rw returns a writable container to the invocant (see more details here: return-rw).

(Mu) method emit

method emit()

Emits the invocant into the enclosing supply or react block.

react { whenever supply { .emit for "foo"42.5 } {
    say "received {.^name} ($_)";
}}
 
# OUTPUT: 
# received Str (foo) 
# received Int (42) 
# received Rat (0.5) 

(Mu) method take

method take()

Returns the invocant in the enclosing gather block.

sub insert($sep+@list{
    gather for @list {
        FIRST .takenext;
        take slip $sep.item
    }
}
 
say insert ':', <a b c>;
# OUTPUT: «(a : b : c)␤» 

(Mu) routine take

sub take(\item)

Takes the given item and passes it to the enclosing gather block.

#| randomly select numbers for lotto 
my $num-selected-numbers = 6;
my $max-lotto-numbers = 49;
gather for ^$num-selected-numbers {
    take (1 .. $max-lotto-numbers).pick(1);
}.say;    # six random values 

(Mu) routine take-rw

sub take-rw(\item)

Returns the given item to the enclosing gather block, without introducing a new container.

my @a = 1...3;
sub f(@list){ gather for @list { take-rw $_ } };
for f(@a{ $_++ };
say @a;
# OUTPUT: «[2 3 4]␤» 

(Mu) method so

method so()

Returns a Bool value representing the logical non-negation of an expression. One can use this method similarly to the English sentence: "If that is so, then do this thing". For instance,

my @args = <-a -e -b -v>;
my $verbose-selected = any(@argseq '-v' | '-V';
if $verbose-selected.so {
    say "Verbose option detected in arguments";
} # OUTPUT: «Verbose option detected in arguments␤» 

(Mu) method not

method not()

Returns a Bool value representing the logical negation of an expression. Thus it is the opposite of so.

my @args = <-a -e -b>;
my $verbose-selected = any(@argseq '-v' | '-V';
if $verbose-selected.not {
    say "Verbose option not present in arguments";
} # OUTPUT: «Verbose option not present in arguments␤» 

Since there is also a prefix version of not, the above code reads better like so:

my @args = <-a -e -b>;
my $verbose-selected = any(@argseq '-v' | '-V';
if not $verbose-selected {
    say "Verbose option not present in arguments";
} # OUTPUT: «Verbose option not present in arguments␤»