[](https://github.com/kfly8/Type-Alias/actions) [](https://coveralls.io/r/kfly8/Type-Alias?branch=main) [](https://metacpan.org/release/Type-Alias) # NAME Type::Alias - type alias for type constraints # SYNOPSIS ```perl use Type::Alias -declare => [qw(ID User List)]; use Types::Standard -types; type ID => Str; type User => { id => ID, name => Str, age => Int, }; type List => sub($R) { $R ? ArrayRef[$R] : ArrayRef; }; # => # ArrayRef[ # Dict[ # age=>Int, # id=>Str, # name=>Str # ] # ] ``` # DESCRIPTION Type::Alias creates type aliases for existing type constraints such as Type::Tiny, Moose. The aim of this module is to enhance the reusability of types and make it easier to express types. ## IMPORT OPTIONS ### -declare `-declare` is an array reference that defines type aliases. The default is `[]`. ```perl use Type::Alias -declare => [qw(ID User List)]; ``` ### -type\_alias `-type_alias` is a function name that defines type aliases. The default name is **type**. ```perl use Type::Alias -type_alias => 'mytype'; mytype ID => Str; # declare type alias ``` ### -export\_ok `-export_ok` is an array reference that defines type aliases to be exported. The default is all type aliases defined by `-declare`. ```perl # Default case: use Type::Alias -declare => [qw(ID User List)]; our @EXPORT_OK; # => qw(ID User List); # Specify export_ok: use Type::Alias -declare => [qw(ID User List)], -export_ok => [qw(List)]; our @EXPORT_OK; # => qw(List); ``` ## EXPORTED FUNCTIONS ### type($alias\_name, $type\_alias\_args) `type` is a function that defines type aliases. The default name is **type**. Given a type constraint in `$type_alias_args`, it returns the type constraint as is. Type::Alias treats objects with `check` and `get_message` methods as type constraints. ```perl type ID => Str; # sub ID(;$) { Str } ``` Given a hash reference in `$type_alias_args`, it returns the type constraint defined by Type::Tiny's Dict type. ```perl type Point => { x => Int, y => Int, }; # sub Point(;$) { Dict[x=>Int,y=>Int] } ``` Given an array reference in `$type_alias_args`, it returns the type constraint defined by Type::Tiny's Tuple type. ```perl type Option => [Str, Int]; # sub Option(;$) { Tuple[Str,Int] } ``` Given a code reference in `$type_alias_args`, it defines a type function that accepts a type constraint as an argument and return the type constraint. ```perl type List => sub($R) { $R ? ArrayRef[$R] : ArrayRef; }; # sub List :prototype(;$) { # my $R = Type::Alias::to_type($_[0]); # $R ? ArrayRef[$R] : ArrayRef; # } ``` Internally, it recursively generates Type::Tiny type constraints based on `$type_alias_args` using the Type::Alias::to\_type function. # LICENSE Copyright (C) kobaken. This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself. # AUTHOR kobaken <kfly@cpan.org>