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)  returns Str:D
multi method chop(Str:D: $chars = 1) returns Str:D

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

routine chomp

Defined as:

multi sub    chomp(Str:D ) returns Str:D
multi method chomp(Str:D:) returns 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");       # abc
say "def\r\n".chomp;      # def  NOTE: \r\n is a single grapheme!
say "foo\r".chomp;        # foo

routine lc

Defined as:

multi sub    lc(Str:D ) returns Str:D
multi method lc(Str:D:) returns Str:D

Returns a lower-case version of the string.

Examples:

lc("A"); # returns "a"
"A".lc;  # returns "a"

routine uc

multi sub    uc(Str:D ) returns Str:D
multi method uc(Str:D:) returns Str:D

Returns an uppercase version of the string.

routine fc

multi sub    fc(Str:D ) returns Str:D
multi method fc(Str:D:) returns 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 ) returns Str:D
multi method tc(Str:D:) returns 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 ) returns Str:D
multi method tclc(Str:D:) returns Str:D

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

routine wordcase

multi sub    wordcase(Cool $x)  returns Str
multi sub    wordcase(Str:D $x) returns Str
multi method wordcase(Str:D: :&filter = &tclc, Mu :$where = True) returns 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) returns Numeric

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

say '4'.unival;     # 4
say '¾'.unival;     # 0.75
say 'a'.unival;     # NaN

method univals

multi method univals(Str:D) returns List

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

say "4a¾".univals;  # (4 NaN 0.75)

routine chars

multi sub    chars(Cool $x)  returns Int:D
multi sub    chars(Str:D $x) returns Int:D
multi sub    chars(str $x)   returns int
multi method chars(Str:D:)   returns 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) returns 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 $s, Str:D $needle, Cool $startpos = 0) returns Int
multi method index(Cool $needle, Cool $startpos = 0) returns 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";     # 1
say index "Camelia is a butterfly", "a", 2;  # 6
say index "Camelia is a butterfly", "er";    # 17
say index "Camelia is a butterfly", "Camel"; # 0
say index "Camelia is a butterfly", "Onion"; # Nil

say index("Camelia is a butterfly", "Onion").defined ?? 'OK' !! 'NOT'; # NOT

routine rindex

multi sub    rindex(Str:D $haystack, Str:D $needle, Int $startpos = $haystack.chars) returns Int
multi method rindex(Str:D $haystack: Str:D $needle, Int $startpos = $haystack.chars) returns 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";     # 11
say rindex "Camelia is a butterfly", "a", 10; # 6

method match

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

TODO

routine parse-base

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

Performs the reverse of base by converting a string with a base-$radix number to its base-10 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; # 1337
'Perl6'.parse-base(30).say;       # 20652936
'FF.DD'.parse-base(16).say;       # 255.863281

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

routine split

multi sub    split(  Str:D $delimiter, Str:D $input, $limit = Inf,
  :$skip-empty, :$v, :$k, :$kv, :$p) returns Positional
multi sub    split(Regex:D $delimiter, Str:D $input, $limit = Inf,
  :$skip-empty, :$v, :$k, :$kv, :$p) returns Positional
multi sub    split(List:D $delimiters, Str:D $input, $limit = Inf,
  :$skip-empty, :$v, :$k, :$kv, :$p) returns Positional
multi method split(Str:D:   Str:D $delimiter, $limit = Inf,
  :$skip-empty, :$v, :$k, :$kv, :$p) returns Positional
multi method split(Str:D: Regex:D $delimiter, $limit = Inf,
  :$skip-empty, :$v, :$k, :$kv, :$p) returns Positional
multi method split(Str:D: List:D $delimiters, $limit = Inf,
  :$skip-empty, :$v, :$k, :$kv, :$p) returns 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;            # ("a", "b", "c")
    say split(";", "a;b;c", :v).perl;        # ("a", ";", "b", ";", "c")
    say split(";", "a;b;c", 2).perl;         # ("a", "b;c").Seq
    say split(";", "a;b;c", 2, :v).perl;     # ("a", ";", "b;c")
    say split(";", "a;b;c,d").perl;          # ("a", "b", "c,d")
    say split(/\;/, "a;b;c,d").perl;         # ("a", "b", "c,d")
    say split(<; ,>, "a;b;c,d").perl;        # ("a", "b", "c", "d")
    say split(/<[;,]>/, "a;b;c,d").perl;     # ("a", "b", "c", "d")
    say split(<; ,>, "a;b;c,d", :k).perl;    # ("a", 0, "b", 0, "c", 1, "d")
    say split(<; ,>, "a;b;c,d", :kv).perl;   # ("a", 0, ";", "b", 0, ";", "c", 1, ",", "d")

    say "".split("x").perl;                  # ("",)
    say "".split("x", :skip-empty).perl;     # ("",)

    say "abcde".split("").perl;              # ("", "a", "b", "c", "d", "e", "")
    say "abcde".split("",:skip-empty).perl;  # ("a", "b", "c", "d", "e")

routine comb

multi sub    comb(Str:D   $matcher, Str:D $input, $limit = Inf)
multi sub    comb(Regex:D $matcher, Str:D $input, $limit = Inf, Bool :$match)
multi sub    comb(Int:D $size, Str: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, $limit = Inf, Bool :$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;                 # ("a", "b", "c").Seq
say comb(/\w/, "a;b;c").perl;        # ("a", "b", "c").Seq
say comb(/\N/, "a;b;c").perl;        # ("a", ";", "b", ";", "c").Seq
say comb(/\w/, "a;b;c", 2).perl;     # ("a", "b").Seq
say comb(/\w\;\w/, "a;b;c", 2).perl; # ("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) returns Positional
multi method lines(Str:D $input: $limit = Inf) returns 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;    # ("a", "b").Seq
say lines("a\nb").elems;   # 2
say "a\nb".lines.elems;    # 2
say "a\n".lines.elems;     # 1

routine words

multi sub    words(Str:D $input, $limit = Inf) returns Positional
multi method words(Str:D $input: $limit = Inf) returns 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;       # ("a", "b").Seq
say "hello world".words.perl;  # ("hello", "world").Seq
say "foo:bar".words.perl;      # ("foo:bar",).Seq
say "foo:bar\tbaz".words.perl; # ("foo:bar", "baz").Seq

routine flip

multi sub    flip(Str:D ) returns Str:D
multi method flip(Str:D:) returns Str:D

Returns the string reversed character by character.

Examples:

"Perl".flip;  # lreP
"ABBA".flip;  # ABBA

sub sprintf

multi sub sprintf( Str:D $format, *@args) returns 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', 12, 34;      # "34 12"
sprintf '%3$d %d %1$d', 1, 2, 3;  # "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;   # "< 12>"
sprintf '<% d>',   0;   # "< 0>"
sprintf '<% d>', -12;   # "<-12>"
sprintf '<%+d>',  12;   # "<+12>"
sprintf '<%+d>',   0;   # "<+0>"
sprintf '<%+d>', -12;   # "<-12>"
sprintf '<%6s>',  12;   # "<    12>"
sprintf '<%-6s>', 12;   # "<12    >"
sprintf '<%06s>', 12;   # "<000012>"
sprintf '<%#o>',  12;   # "<014>"
sprintf '<%#x>',  12;   # "<0xc>"
sprintf '<%#X>',  12;   # "<0XC>"
sprintf '<%#b>',  12;   # "<0b1100>"
sprintf '<%#B>',  12;   # "<0B1100>"

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

sprintf '<%+ d>', 12;   # "<+12>"
sprintf '<% +d>', 12;   # "<+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>', 012;      # "<000012>"
sprintf '<%#.5o>', 012345;   # "<012345>"
sprintf '<%#.0o>', 0;        # "<>" # 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"
  NYI sprintf "version is v%vd\n", $^V;     # Perl 6's version

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";           # "<a>"
sprintf "<%6s>", "a";          # "<     a>"
sprintf "<%*s>", 6, "a";       # "<     a>"
 NYI sprintf '<%*2$s>', "a", 6; # "<     a>"
sprintf "<%2s>", "long";       # "<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;    # "<1.000000>"
sprintf '<%.1f>', 1;  # "<1.0>"
sprintf '<%.0f>', 1;  # "<1>"
sprintf '<%e>', 10;   # "<1.000000e+01>"
sprintf '<%.1e>', 10; # "<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;        # "<1>"
sprintf '<%.10g>', 1;     # "<1>"
sprintf '<%g>', 100;      # "<100>"
sprintf '<%.1g>', 100;    # "<1e+02>"
sprintf '<%.2g>', 100.01; # "<1e+02>"
sprintf '<%.5g>', 100.01; # "<100.01>"
sprintf '<%.4g>', 100.01; # "<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;      # "<000001>"
sprintf '<%#.6x>', 1;     # "<0x000001>"
sprintf '<%-10.6x>', 1;   # "<000001    >"
sprintf '<%10.6x>', 1;    # "<    000001>"
sprintf '<%010.6x>', 1;   # "<    000001>"
sprintf '<%#10.6x>', 1;   # "<  0x000001>"

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

sprintf '<%.5s>', "truncated";   # "<trunc>"
sprintf '<%10.5s>', "truncated"; # "<     trunc>"

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

sprintf '<%.6x>', 1;       # "<000001>"
sprintf '<%.*x>', 6, 1;    # "<000001>"
NYI sprintf '<%.*2$x>', 1, 6;  # "<000001>"
NYI sprintf '<%6.*2$x>', 1, 4; # "<  0001>"

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

sprintf '<%.*s>',  7, "string";   # "<string>"
sprintf '<%.*s>',  3, "string";   # "<str>"
sprintf '<%.*s>',  0, "string";   # "<>"
sprintf '<%.*s>', -1, "string";   # "<string>"
sprintf '<%.*d>',  1, 0;          # "<0>"
sprintf '<%.*d>',  0, 0;          # "<>"
sprintf '<%.*d>', -1, 0;          # "<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 = 5; my $b = 2; my $c = 'net';
sprintf "<%*.*s>", $a, $b, $c; # <   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",      12, 34;     # "34 12\n"
sprintf "%2\$d %d %d\n",   12, 34;     # "34 12 34\n"
sprintf "%3\$d %d %d\n",   12, 34, 56; # "56 12 34\n"
NYI sprintf "%2\$*3\$d %d\n",  12, 34,  3; # " 34 12\n"
NYI sprintf "%*1\$.*f\n",       4,  5, 10; # "5.0000\n"

Other examples:

NYI sprintf "%ld a big number", 4294967295;
NYI sprintf "%%lld a bigger number", 4294967296;
sprintf('%c', 97);                  # a
sprintf("%.2f", 1.969);             # 1.97
sprintf("%+.3f", 3.141592);         # +3.142
sprintf('%2$d %1$d', 12, 34);       # 34 12
sprintf("%x", 255);                 # 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"; # "<b>Perl 6</b>\n"
 sprintf     "<b>\%s</b>\n", "Perl 6"; # "<b>Perl 6</b>\n"
 sprintf     "<b>%s\</b>\n", "Perl 6"; # "<b>Perl 6</b>\n"

method starts-with

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

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

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

method ends-with

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

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

say "Hello, World".ends-with('Hello');      # False
say "Hello, World".ends-with('ld');         # 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.

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'

The replacement can be a closure:

my $i = 41;
my $str = "The answer is secret.";
my $real-answer = $str.subst(/secret/, {++$i}); # The answer to everything

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; xoooo
say 'ooooo'.subst: 'o', 'x', :2nd; oxooo
say 'ooooo'.subst: 'o', 'x', :3rd; ooxoo
say 'ooooo'.subst: 'o', 'x', :4th; oooxo

The following adverbs are supported

short long meaning
:g :global tries to match as often as possible
:nth(Int|Callable) 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|Callable) 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;  #-> Some string
say $match;        #-> 「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 $s, Int:D $from, Int:D $chars = $s.chars - $from) returns Str:D
multi sub    substr(Str:D $s, Range $from-to) returns Str:D
multi method substr(Str:D $s: Int:D $from, Int:D $chars = $s.chars - $from) returns Str:D
multi method substr(Str:D $s: Range $from-to) returns 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", 6, 3);     # tri
substr("Long string", 6);        # tring
substr("Long string", 6, *-1);   # trin
substr("Long string", *-3, *-1); # in

method substr-eq

multi method substr-eq(Str:D:  Str(Cool) $test-string, Int(Cool) $from) returns Bool
multi method substr-eq(Cool:D: Str(Cool) $test-string, Int(Cool) $from) returns 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);  #-> 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);  #-> False

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

my $string = "foobar";
say $string.substr-eq("foobar", 0);  #-> 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(42, 1);  #-> True

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

my $integer = 342;
say $integer.substr-eq(342, 0);  #-> True

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

my $integer = 342;
say $integer.substr-eq(42, 3);  #-> False
say $integer.substr-eq(7342, 0);  #-> 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 do this:

my $string = "abc";
$string.substr-rw(1, 1) = "z";
$string.say;                    #-> azc

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

my $string = "abc";
substr-rw($string, 1, 1) = "z";
$string.say;                    #-> azc

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;
# A character in the 'Flintstones' is: barney
$ref = "fred";
$string.say;
# A character in the 'Flintstones' is: fred
$ref = "wilma";
$string.say;
# 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 $string, Str:D $pattern) returns Str:D
method    samemark(Str:D: Str:D $pattern) returns 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');                        # aäo
say 'åäö'.samemark('a');                          # aao

say samemark('Pêrl', 'a');                        # Perl
say samemark('aöä', '');                          # aöä

method succ

method succ(Str:D) returns 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;      # 13.34
'img001.png'.succ; # 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;   # ab
'az'.succ;   # ba
'109'.succ;  # 110
'α'.succ;    # β
'a9'.succ;   # 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:) returns Str:D

Returns the string decremented by one.

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

'b0'.pred;           # a9
'a0'.pred;           # Failure
'img002.png'.pred;   # img001.png

routine ord

multi sub    ord(Str:D)  returns Int:D
multi method ord(Str:D:) returns 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:) returns 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

proto method trans(|)
multi method trans(Str:D: Pair:D \what, *%n) returns Str
multi method trans(Str:D: *@changes, :complement(:$c), :squash(:$s), :delete(:$d)) returns 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/ => ''); # «cdgh»

"a123b123c".trans(['a'..'z'] => 'x', :complement); # «axxxbxxxc»
"a123b123c".trans('23' => '', :delete); # «a1b1c»
"aaa1123bb123c".trans('a'..'z' => 'A'..'Z', :squash); # «A1123B123C»
"aaa1123bb123c".trans('a'..'z' => 'x', :complement, :squash); # «aaaxbbxc»

method indent

proto 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:) returns Str

Remove leading and trailing whitespace. It can be use 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, once needs to write .=trim

my $line = '   hello world    ';
say '<' ~ $line.trim ~ '>';        # <hello world>
say '<' ~ trim($line) ~ '>';       # <hello world>
$line.trim;
say '<' ~ $line ~ '>';             # <   hello world    >
$line.=trim;
say '<' ~ $line ~ '>';             # <hello world>

See also trim-trailing and trim-leading

method trim-trailing

method trim-trailing(Str:D:) returns Str

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

method trim-leading

method trim-leading(Str:D:) returns Str

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

method NFC

method NFC(Str:D:) returns NFC:D

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

method NFD

method NFD(Str:D:) returns NFD:D

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

method NFKC

method NFKC(Str:D:) returns NFKC:D

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

method NFKD

method NFKD(Str:D:) returns NFKD:D

Returns a codepoint string in NFC 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; # (IntStr)
say val("42e0").WHAT; # (NumStr)
say val("42.0").WHAT; # (RatStr)
say val("42+0i").WHAT; # (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, raster

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;       # 2
say abs "6+8i";     # 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;        # 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;             # 2
say sqrt(2);            # 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;             # 1
say (-6).sign;          # -1
say "0".sign;           # 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;           # 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);             # 0
say sin(pi/4);          # 0.707106781186547
say sin(pi/2);          # 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;               # 0.10016742116156
say asin(0.1);              # 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;                  # 1
say pi.cos;                 # -1
say cos(pi/2);              # 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;                 # 0
say acos(-1);               # 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);                 # -0.142546543074278
say 3.tan;                  # -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);                # 1.24904577239825
say 3.atan;                 # 1.24904577239825

(Cool) routine atan2

Defined as:

sub atan2(Numeric() $x, Numeric() $y = 1e0)
method atan2($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);               # 1.24904577239825
say 3.atan2;                # 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;                 # 1.90359440740442
say sec(45);                # 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;                 # 0
say sqrt(2).asec;           # 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;             # 2.29903273150897
say cosec(0.45);            # 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;              # 0.0222240516182672
say acosec(45)              # 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;               # 0.617369623783555
say cotan(45);              # 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;              # 0.0222185653267191
say acotan(45)              # 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;                 # 1.1752011936438
say sinh(1);                # 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;                # 0.881373587019543
say asinh(1);               # 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);              # 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);              # 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);              # 0.46211715726001
say tanh(atanh(0.5));       # 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);             # 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;                 # 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;              # 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);           # 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);           # 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);             # 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);           # 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);              # 0.707106781186548+0.707106781186547i

(Cool) routine log

Defined as:

multi sub log(Numeric(Cool) $number, Numeric(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;              # 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);            # 3.00043407747932

(Cool) method exp

Defined as:

multi sub exp(Cool:D $pow, Cool: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;      # 1
say 1.exp;      # 2.71828182845905
say 10.exp;     # 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);      # 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;          # 2
say 1.07.round(0.1);    # 1.1
say 21.round(10);       # 20

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

say (−.5 ).round;       # 0
say ( .5 ).round;       # 1
say (−.55).round(.1);   # -0.5
say ( .55).round(.1);   # 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;       # 1
say "-1.9".floor;       # -2
say 0.floor;            # 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;        # 1
say "-0.9".ceiling;     # 0
say "42.1".ceiling;     # 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;       # 1
say truncate -1.2;      # -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;            # 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;       # 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;    # 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;    # 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;       # 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>";          # <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>";          # <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>";          # <  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;       # 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;       # 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;       # 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;       # 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;     # Abc

(Cool) routine wordcase

Defined as:

sub wordcase(Str(Cool) $input, :&filter = &tclc, Mu :$where = True)
method wordcase(:&filter = &tclc, Mu :$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;      # 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 $string, Cool $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__"); # Perl 6
say "pERL 6".samecase("Ab");     # Perl 6

(Cool) routine uniname

Defined as:

sub uniname(Str(Cool)) returns Str
method uniname() returns Str

Interprets the invocant / first argument as a Str, and returns the Unicode codepoint name of the first character. To convert a whole string use uninames.

# Camelia in Unicode
say ‘»ö«’.comb».uniname;
# «("RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK",
#   "LATIN SMALL LETTER O WITH DIAERESIS", "LEFT-POINTING DOUBLE ANGLE QUOTATION MARK")␤»

# Find the char with the longest Unicode name.
say (0..0x1FFFF).sort(*.uniname.chars)[*-1].chr.uniname;
# «ARABIC LIGATURE UIGHUR KIRGHIZ YEH WITH HAMZA ABOVE WITH ALEF MAKSURA INITIAL FORM␤»

(Cool) routine uninames

Defined as:

sub uninames(Str:D)
method uninames()

Returns of a Seq of unicode names for the Str provided.

dd ‘»ö«’.comb».uniname;
# «("RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK",
#  "LATIN SMALL LETTER O WITH DIAERESIS",
#  "LEFT-POINTING DOUBLE ANGLE QUOTATION MARK").Seq␤»

(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;                        # 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;                   # 2
say "a\n".chomp.chars;                  # 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);         # nith
say 'zenith'.substr(0, 3);      # zen

# works on non-strings too:
say 20151224.substr(6);         # 24

# sub form:
say substr "zenith", 0, 3;      # 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);       # 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 "Perl 6".ords;              # 80 101 114 108 160 54
say ords 10;                    # 49 48

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

(Cool) routine chrs

Defined as:

sub chrs(*@codepoints) returns 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 <80 101 114 108 160 54>.chrs;   # Perl 6

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

(Cool) routine split

Defined as:

multi sub    split(  Str:D $delimiter, Str(Cool) $input, $limit = Inf, :$k, :$v, :$kv, :$p, :$skip-empty)
multi sub    split(Regex:D $delimiter, Str(Cool) $input, $limit = Inf, :$k, :$v, :$kv, :$p, :$skip-empty)
multi sub    split(@delimiters, Str(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;          # ("a", "b", "c")
say split(';', "a;b;c", 2).perl;       # ("a", "b;c").Seq

say split(';', "a;b;c,d").perl;        # ("a", "b", "c,d")
say split(/\;/, "a;b;c,d").perl;       # ("a", "b", "c,d")
say split(/<[;,]>/, "a;b;c,d").perl;   # ("a", "b", "c", "d")

say split(['a', /b+/, 4], '1a2bb345').perl # ("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);               # (a 「b」 c)
say 'abc'.split('b', :v);               # (a b c)

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

say 'abc'.split(/b/, :k);               # (a 0 c)

:kv adds both indexes and matches:

say 'abc'.split(/b/, :kv);               # (a 0 「b」 c)

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

say 'abc'.split(/b/, :p);               # (a 0 => 「b」 c)
say 'abc'.split('b', :p);               # (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;  # ("f", "", "b", "c", "d")
say ("f,,b,c,d".split: /","/, :skip-empty).perl;  # ("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('|');          # a|b
say "some\nmore\nlines".lines.elems;    # 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('|');      # The|quick|brown|fox
say 'The quick brown fox'.words(2).join('|');   # The|quick

Only whitespace counts as word boundaries

say "isn't, can't".words.join('|');             # isn't,|can't

(Cool) routine comb

Defined as:

multi sub comb(Regex $matcher, Str(Cool) $input, $limit = *) returns List:D
multi method comb(Regex $matcher, $limit = *) returns List:D

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(", ");           # 6, 12

(Cool) method contains

multi method contains(Cool:D: Str(Cool) $needle, Cool $start?) returns Bool:D

Returns True if the invocant contains the $needle at any position within the string. If $start is provided skip as many characters.

say "Hello, World".contains('hello');      # False
say "Hello, World".contains(',');          # True

(Cool) routine index

Defined as:

multi sub    index(Str(Cool) $s, Str:D $needle, Int(Cool) $startpos = 0) returns Int
multi method index(Str(Cool) $needle, Int(Cool) $startpos = 0) returns 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) $haystack, Str(Cool) $needle, Int(Cool) $startpos = $haystack.chars)
multi method rindex(Str(Cool) $haystack: Str(Cool) $needle, Int(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') returns 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');               # This Int equals 011
say '16'.fmt('Hexadecimal %x');                   # Hexadecimal 10

(Cool) routine roots

Defined as:

multi sub roots(Numeric(Cool) $x, Int(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() returns 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. If you have a more complex input, such as a variable or string with embedded code, you must enable the MONKEY-SEE-NO-EVAL pragma:

use MONKEY-SEE-NO-EVAL;
EVAL "say { 5 + 5 }";   # says 10

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

my $answer = 42;
EVAL 'say $answer;';    # says 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;         # says 42

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

sub infix:<mean>(*@a) is assoc<list> {
    @a.sum / @a.elems
}
EVAL 'say 2 mean 6 mean 4';     # says 4

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

sub infix:<mean>(*@a) is assoc<list> {
    @a.sum / @a.elems
}
say EVAL 'say 1; 2 mean 6 mean 4';         # says 1, then says 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() returns Junction:D

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

say so 2 == <1 2 3>.any;        # True
say so 5 == <1 2 3>.any;        # False

(Any) method all

Defined as:

method all() returns Junction:D

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

say so 1 < <2 3 4>.all;         # True
say so 3 < <2 3 4>.all;         # False

(Any) method one

Defined as:

method one() returns Junction:D

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

say so 1 == (1, 2, 3).one;      # True
say so 1 == (1, 2, 1).one;      # False

(Any) method none

Defined as:

method none() returns Junction:D

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

say so 1 == (1, 2, 3).none;     # False
say so 4 == (1, 2, 3).none;     # True

(Any) method list

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

say 42.list.^name;           # List
say 42.list.elems;           # 1

(Any) method push

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 therefor 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 ) returns List:D
multi method reverse(List:D:) returns List:D

Returns a list 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;     # (world! hello)
say reverse ^10;                # (9 8 7 6 5 4 3 2 1 0)

(Any) method sort

Sorts iterables with infix:<cmp> or given code object and returns a new List.

Examples:

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

(Any) method map

Defined as:

proto method map(|) is nodal { * }
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 -->List) is 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(&block) is 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.

my @a = [1,[2,3],4];
dd @a.duckmap({ $_ ~~ Int ?? $_++ !! Any });
# OUTPUT«(1, (2, 3), 4)␤»

(Any) method flat

Interprets the invocant as a list, flattens it, and returns that list. Please note that .flat will not solve the halting problem for you. If you flat an infinite list .flat may return that infinite list, eating all your RAM in the process.

say ((1, 2), (3)).elems;        # 2
say ((1, 2), (3)).flat.elems;   # 3

Please not that flat is not recursing into sub lists. You have to recurse by hand or reconsider your data structures. A single level of nesting can often be handled with destructuring in signatures. For deeper structures you may consider gather/take to create a lazy list.

my @a = [[1,2,3],[[4,5],6,7]];
sub deepflat(@a){
    gather for @a {
        take ($_ ~~ Iterable ?? deepflat($_).Slip !! $_)
    }
};
dd deepflat(@a);
# OUTPUT«(1, 2, 3, 4, 5, 6, 7).Seq␤»

(Any) method eager

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

say (1..10).eager;              # (1 2 3 4 5 6 7 8 9 10)

(Any) method elems

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

say 42.elems;                   # 1
say <a b c>.elems;              # 3

(Any) method end

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

say 6.end;                      # 0
say <a b c>.end;                # 2

(Any) method pairup

method pairup() returns List

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 (a => 1, 'b', 'c').pairup.perl;     # (:a(1), :b("c")).Seq

(Any) sub exit

sub exit(Int() $status = 0)

Exits the current process with return code $status.

Routines supplied by class Mu

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

(Mu) routine defined

multi sub    defined(Mu) returns Bool:D
multi method defined()   returns Bool:D

Returns False on the type object, and True otherwise.

say Int.defined;                # False
say 42.defined;                 # True

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

sub fails() { fail 'oh noe' };
say fails().defined;            # False

(Mu) routine isa

multi method isa(Mu $type)      returns Bool:D
multi method isa(Str:D $type)   returns 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");   # True
say $i.isa(Any);     # True

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

my $s = "String";
say $s ~~ Str;       # True

(Mu) routine does

method does(Mu $type)      returns 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;                # True
say $d ~~ Any;                    # True
say $d ~~ DateTime;               # False

(Mu) routine Bool

multi sub    Bool(Mu) returns Bool:D
multi method Bool()   returns 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;                    # False
say Mu.new.Bool;                # True
say [1, 2, 3].Bool;             # True
say [].Bool;                    # False
say { 'hash' => 'full'}.Bool;   # True
say {}.Bool;                    # False

(Mu) method Str

multi method Str()   returns 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(Mu) returns Str
multi method gist()   returns 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, so say $something and say $something.gist generally produce the same output.

say Mu.gist;        # (Mu)
say Mu.new.gist;    # Mu.new

(Mu) routine perl

multi sub    perl(Mu) returns Str
multi method perl()   returns 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 clone

method clone(*%twiddles)

Creates a shallow clone of the invocant. If named arguments are passed to it, their values are used in every place where an attribute name matches the name of a named argument.

class Point2D {
    has ($.x, $.y);
    multi method gist(Point2D:D:) {
        "Point($.x, $.y)";
    }
}

my $p = Point2D.new(x => 2, y => 3);

say $p;                     # Point(2, 3)
say $p.clone(y => -5);      # 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) returns 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(-1, 1);

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

(Mu) method CREATE

method CREATE() returns Mu:D

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

say Mu.CREATE.defined;  # True

(Mu) method print

multi method print() returns Bool:D

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

"abc\n".print;          # abc␤

(Mu) method put

multi method put() returns Bool:D

Prints value to $*OUT after stringification using .Str method adding a newline at end.

"abc".put;              # abc␤

(Mu) method say

multi method say() returns Bool:D

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

say 42;                 # 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;           # True
say 42 ~~ Int;          # True
say 42 ~~ Str;          # 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() returns 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;       # True

(Mu) method WHERE

method WHERE() returns 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 .take, next;
        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;    #-> 32 22 1 17 32 9  (for example)

(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(@args) eq '-v' | '-V';
if $verbose-selected.so {
    say "Verbose option detected in arguments";
} #-> 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(@args) eq '-v' | '-V';
if $verbose-selected.not {
    say "Verbose option not present in arguments";
} #-> 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(@args) eq '-v' | '-V';
if not $verbose-selected {
    say "Verbose option not present in arguments";
} #-> Verbose option not present in arguments