Raku Land

PatternMatching

zef:CIAvash

NAME

PatternMatching

DESCRIPTION

PatternMatching is a Raku module for pattern matching.

It provides match_pattern infix operator and as an alias for it. It accepts a topic and a list of patterns(Codes) and can be used like $topic match_pattern -> $some_pattern {...}.

If the topic doesn't match any of the patterns, a Failure containing the X::PatternMatching::MatchFailed exception will be returned.

Info for :

SYNOPSIS

use PatternMatching:auth<zef:CIAvash>;

class C { has $.a = 'attribute' }

my @a = 1, [2, 3], 'a', <b c>, :d(4), :e[5, 6], 10, 'f', 'g', 'h', 20,
        C.new, PatternMatching, :g(8, 2), [7, 8, 9];

my @b = @a.map: * match_pattern
          -> 10 { 'ten' },
          -> Int $a where * > 10 { 'twenty' },
          -> Int $a { $a + 2 },
          -> Str $a where any <f g h> { 'f or g or h' },
          -> Str $a { $a.succ },
          -> C (:$a) { $a },
          -> @ (Str $a, Str $b) { join ' | ', $a, $b },
          -> @ (Int $a, Int $b) { $a + $b },
          -> @ (Int $a, *@b where .all ~~ Int) { [+] $a, |@b },
          -> Pair (:key($a), :value([$b, $c])) { "$a: {$b + $c}" },
          -> Hash() (:$g ($a, $b)) { "$g: {$a + $b}" },
          -> Pair $pair { $pair.kv.join: ': ' },
          -> | { 'default' }

put @b.raku;
=output [3, 5, "b", "b | c", "d: 4", "e: 11", "ten", "f or g or h", "f or g or h", "f or g or h", "twenty",
"attribute", "default", "g: 10", 24]my @c = @a.map: *-> @ (Str $a, Str $b) { join ' | ', $a, $b },
          -> @ (Int $a, Int $b) { $a + $b },
          -> | { 'default' }

put @c.raku;
=output ["default", 5, "default", "b | c", "default", "default", "default", "default", "default", "default",
"default", "default", "default", "default", "default"]for @a {
    .put with .&[match_pattern]:
                -> 10 { 'ten' },
                -> Int $a where * > 10 { 'twenty' },
                -> Int $a { $a + 2 },
                -> Str $a where any <f g h> { 'f or g or h' },
                -> Str $a { $a.succ },
                -> C (:$a) { $a };
                -> @ (Str $a, Str $b) { join ' | ', $a, $b },
                -> @ (Int $a, Int $b) { $a + $b },
                -> @ (Int $a, *@b where .all ~~ Int) { [+] $a, |@b },
                -> Pair (:key($a), :value([$b, $c])) { "$a: {$b + $c}" },
                -> Hash() (:$g ($a, $b)) { "$g: {$a + $b}" },
                -> Pair $pair { $pair.kv.join: ': ' },
}

INSTALLATION

You need to have Raku and zef, then run:

zef install --/test "PatternMatching:auth<zef:CIAvash>"

or if you have cloned the repo:

zef install .

TESTING

prove -ve 'raku -I.' --ext rakutest

SUBS

sub infix:<match_pattern>

sub infix:<match_pattern>(
    $topic,
    *@functions where { ... }
) returns Mu

Matches topic against a list of patterns(functions).

Returns Failure(X::PatternMatching::MatchFailed) when no pattern is matched.

sub infix:<┇>

&infix:<> = &[match_pattern]

Alias for match_pattern

ERRORS

If the topic doesn't match any of the patterns, a Failure containing the X::PatternMatching::MatchFailed exception will be returned.

REPOSITORY

https://github.com/CIAvash/PatternMatching/

BUG

https://github.com/CIAvash/PatternMatching/issues

AUTHOR

Siavash Askari Nasr - https://www.ciavash.name

COPYRIGHT

Copyright © 2021 Siavash Askari Nasr

LICENSE

This file is part of PatternMatching.

PatternMatching is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at yoption) any later version.

PatternMatching is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with PatternMatching. If not, see http://www.gnu.org/licenses/.