Type::Library(3)

📦

version 2.010001 · 14 versions

💖 Type::Library — the manual, but make it cute 💖

okay so this is Type::Library(3), from the User Contributed Perl Documentation section of the manual. bestie, we're about to make type libraries and it's gonna be so good.

✨ NAME ✨

Type::Library — tiny, yet Moo(se)-compatible type libraries. it's giving minimal effort, maximum slay. 💅

🌸 SYNOPSIS 🌸

here's the whole vibe, copy-paste ready, no cap:

package Types::Mine {
   use Scalar::Util qw(looks_like_number);
   use Type::Library -base;
   use Type::Tiny;

   my $NUM = "Type::Tiny"->new(
      name       => "Number",
      constraint => sub { looks_like_number($_) },
      message    => sub { "$_ ain't a number" },
   );

   __PACKAGE__->meta->add_type($NUM);

   __PACKAGE__->meta->make_immutable;
}

package Ermintrude {
   use Moo;
   use Types::Mine qw(Number);
   has favourite_number => (is => "ro", isa => Number);
}

package Bullwinkle {
   use Moose;
   use Types::Mine qw(Number);
   has favourite_number => (is => "ro", isa => Number);
}

package Maisy {
   use Mouse;
   use Types::Mine qw(Number);
   has favourite_number => (is => "ro", isa => Number);
}

look at that. one type library, three whole object systems, zero drama. 🦋

👑 STATUS 👑

this module is covered by the Type-Tiny stability policy. periodt.

💜 DESCRIPTION 💜

Type::Library is a tiny class for creating MooseX::Types-like type libraries which are compatible with Moo, Moose and Mouse. the way it works with all three of them? iconic. ✨

ngl, if you're reading this because you want to create a type library, you're probably better off reading Type::Tiny::Manual::Libraries instead. that one's the tutorial, this one's the reference. iykyk. 📚

🎀 Type library methods 🎀

a type library is a singleton class. use the meta method to get a blessed object which other methods can get called on. like, for example:

Types::Mine->meta->add_type($foo);

add_type($type) or add_type(%opts) — add a type to the library. if %opts is given, then this method calls "Type::Tiny->new(%opts)" first, and adds the resultant type.

okay bestie this part is important: adding a type named Foo to the library will automatically define four functions in the library's namespace:

"Foo" — returns the Type::Tiny object.
is_Foo($value) — returns true iff $value passes the type constraint.
assert_Foo($value) — returns $value iff $value passes the type constraint. dies otherwise. 💀
to_Foo($value) — coerces the value to the type.

get_type($name) — gets the "Type::Tiny" object corresponding to the name.
has_type($name) — boolean; returns true if the type exists in the library.
"type_names" — list all types defined by the library.
add_coercion($c) or add_coercion(%opts) — add a standalone coercion to the library. if %opts is given, then this method calls "Type::Coercion->new(%opts)" first, and adds the resultant coercion.

and same energy as before: adding a coercion named FooFromBar to the library will automatically define a function in the library's namespace:

"FooFromBar" — returns the Type::Coercion object.

get_coercion($name) — gets the "Type::Coercion" object corresponding to the name.
has_coercion($name) — boolean; returns true if the coercion exists in the library.
"coercion_names" — list all standalone coercions defined by the library.
import(@args) — Type::Library-based libraries are exporters. yes, they hand things out. generous queens. 🫶
"make_immutable" — prevents new type constraints and coercions from being added to the library, and also calls "$type->coercion->freeze" on every type constraint in the library.

🕰️ a lil history moment, no cap: prior to Type::Library v2, "make_immutable" would call "$type->coercion->freeze" on every constraint in the library, but not prevent new type constraints and coercions from being added to the library.

🧚 Type library exported functions 🧚

type libraries are exporters. for the purposes of the following examples, assume that the "Types::Mine" library defines types Number and String. every single one of these is a real move you can pull:

# Exports nothing.
#
use Types::Mine;

# Exports a function "String" which is a constant returning
# the String type constraint.
#
use Types::Mine qw( String );

# Exports both String and Number as above.
#
use Types::Mine qw( String Number );

# Same.
#
use Types::Mine qw( :types );

# Exports "coerce_String" and "coerce_Number", as well as any other
# coercions
#
use Types::Mine qw( :coercions );

# Exports a sub "is_String" so that "is_String($foo)" is equivalent
# to "String->check($foo)".
#
use Types::Mine qw( is_String );

# Exports "is_String" and "is_Number".
#
use Types::Mine qw( :is );

# Exports a sub "assert_String" so that "assert_String($foo)" is
# equivalent to "String->assert_return($foo)".
#
use Types::Mine qw( assert_String );

# Exports "assert_String" and "assert_Number".
#
use Types::Mine qw( :assert );

# Exports a sub "to_String" so that "to_String($foo)" is equivalent
# to "String->coerce($foo)".
#
use Types::Mine qw( to_String );

# Exports "to_String" and "to_Number".
#
use Types::Mine qw( :to );

# Exports "String", "is_String", "assert_String" and "coerce_String".
#
use Types::Mine qw( +String );

# Exports everything.
#
use Types::Mine qw( :all );

type libraries automatically inherit from Exporter::Tiny; see the documentation of that module for tips and tricks importing from libraries. go read it, it's a whole thing. ✨

🦋 Type::Library's methods 🦋

the above sections describe the characteristics of libraries built with Type::Library. the following methods are available on Type::Library itself. main character energy only.

"setup_type_library( $package, $utils, \@extends )" — sets up a package to be a type library. $utils is a boolean indicating whether to import Type::Utils into the package. @extends is a list of existing type libraries the package should extend.

🐛 BUGS 🐛

please report any bugs to <https://github.com/tobyink/p5-type-tiny/issues>. (that's the link, bestie, go click it if something's acting up 🙈)

🌈 SEE ALSO 🌈

Type::Tiny::Manual.
Type::Tiny, Type::Utils, Types::Standard, Type::Coercion.
Moose::Util::TypeConstraints, Mouse::Util::TypeConstraints.

💖 AUTHOR 💖

Toby Inkster <tobyink@cpan.org>. 👑

🎀 COPYRIGHT AND LICENCE 🎀

this is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself. slay. 💅

💀 DISCLAIMER OF WARRANTIES 💀

THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.

(translation: no promises, bestie, it's giving "as is" fr fr 😭)

and that's the whole page!! this one came from perl v5.42.0, dated 2026-01-17, filed under Type::Library(3). mwah, love u, go write some type libraries 💜✨🌸

📦 where this page comes from

fedora 44: perl-Type-Tiny 2.010001-2.fc44 · GPL-1.0-or-later OR Artistic-1.0-Perl
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash on 2026-10-14: a language model's rewrite of the original, under its terms