Eval::TypeTiny(3)

💖 Eval::TypeTiny — the manual, but make it cute 💖

okay bestie, gather round, because this one is genuinely iconic. this is the Eval::TypeTiny(3) page — a lil module that evaluates a string of Perl code in a clean environment. that's the whole vibe. 🦋

---

✨ STATUS ✨

this module is covered by the Type-Tiny stability policy. so like… it's stable, it's committed, it's not gonna ghost you. 💅

---

🌸 DESCRIPTION 🌸

so Type::Tiny uses this thing to do two jobs:

• compile coderefs out of strings of Perl code
• and compile hashrefs of variables to close over

that's it. that's the job. no cap.

---

🎀 Functions 🎀

by default this module exports one function, and it works much like the similarly named function from Eval::Closure:

eval_closure(source => $source, environment => \%env, %opt)

other functions can be imported on request — like, you gotta ask for them, they're not just gonna show up:

• set_subname( $fully_qualified_name, $coderef ) — works like the similarly named function from Sub::Util, except it will fallback to doing absolutely nothing if neither Sub::Util nor Sub::Name are available. also? it will cowardly refuse to set the name of a coderef a second time if it's already named it. boundaries! we love them. 🙈
• type_to_coderef( $type, %options ) — turns a Type::Tiny object into a coderef, suitable for installing into a symbol table to create a function like ArrayRef or Int. (actually it should work for any object which provides is_parameterizable, parameterize, and qualified_name methods, such as Type::Coercion.) 👑

$options{post_method} can be a string of Perl indicating a method to call on the type constraint before returning it. for example '->moose_type'. ✨

$options{description} can be a description of the coderef which may be shown in stack traces, etc. so future-you knows what's up.

the coderef will be named using set_subname unless $options{anonymous} is true. (anonymous? mysterious? we respect it. 🕶️)

if $type is undef, then it is assumed that the type constraint hasn't been defined yet but will later, yet you still want a function now. $options{type_library} and $options{type_name} will be used to find the type constraint when the function gets called. manifesting fr fr 💫

---

💜 Constants 💜

the following constants may be exported, but are not by default. you gotta ask, bestie.

• HAS_LEXICAL_SUBS — boolean indicating whether Eval::TypeTiny has support for lexical subs. (this feature requires Perl 5.18.) ⭐
• ALIAS_IMPLEMENTATION — returns a string indicating what implementation of alias => 1 is being used. Eval::TypeTiny will automatically choose the best implementation. this constant can be matched against the IMPLEMENTATION_* constants. 🎯
• IMPLEMENTATION_NATIVE — if ALIAS_IMPLEMENTATION eq IMPLEMENTATION_NATIVE then Eval::TypeTiny is currently using Perl 5.22's native alias feature. this requires Perl 5.22. 🧚
• IMPLEMENTATION_DEVEL_LEXALIAS — if ALIAS_IMPLEMENTATION eq IMPLEMENTATION_DEVEL_LEXALIAS then Eval::TypeTiny is currently using Devel::LexAlias to provide aliases. 🌈
• IMPLEMENTATION_PADWALKER — if ALIAS_IMPLEMENTATION eq IMPLEMENTATION_PADWALKER then Eval::TypeTiny is currently using PadWalker to provide aliases. 🦋
• IMPLEMENTATION_TIE — if ALIAS_IMPLEMENTATION eq IMPLEMENTATION_TIE then Eval::TypeTiny is using the fallback implementation of aliases using tie. this is the slowest implementation, and may cause problems in certain edge cases, like trying to alias already-tied variables, but it's the only way to implement alias => 1 without a recent version of Perl or one of the two optional modules mentioned above. it's giving last-resort-iconic. 💀
• NICE_PROTOTYPES — if this is true, then type_to_coderef will give parameterizable type constraints the slightly nicer prototype of (;$) instead of the default (;@). this allows constructs like:

ArrayRef[Int] | HashRef[Int]

… to "just work". slay. 💅

---

🔥 EVALUATION ENVIRONMENT 🔥

the evaluation is performed in the presence of strict, but the absence of warnings. (this is different to Eval::Closure which enables warnings for compiled closures.) so like, strict mode said yes, warnings said no thanks. 🫶

the feature pragma is not active in the evaluation environment, so the following will not work:

use feature qw(say);
use Eval::TypeTiny qw(eval_closure);

my $say_all = eval_closure(
   source => 'sub { say for @_ }',
);
$say_all->("Hello", "World");

the feature pragma does not "carry over" into the stringy eval. it is of course possible to import pragmas into the evaluated string as part of the string itself:

use Eval::TypeTiny qw(eval_closure);

my $say_all = eval_closure(
   source => 'sub { use feature qw(say); say for @_ }',
);
$say_all->("Hello", "World");

see? put it inside the string. self-sufficient queen. 👑

---

🐛 BUGS 🐛

please report any bugs to <https://github.com/tobyink/p5-type-tiny/issues>. do not suffer in silence, bestie, that's not the vibe. 😭

---

👀 SEE ALSO 👀

Eval::Closure, Error::TypeTiny::Compilation. go read those too, iykyk. 💖

---

🫶 AUTHOR 🫶

Toby Inkster <tobyink@cpan.org>.

---

📜 COPYRIGHT AND LICENCE 📜

this software is copyright (c) 2013-2014, 2017-2025 by Toby Inkster.

this is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself. free as in, go off. 🕊️

---

💀 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.

okay so like — this part is yelling and it's yelling for a reason. no promises, no guarantees, use at your own risk. periodt. 🚨

---

and that's the whole page, bestie!! 🎀 this was Eval::TypeTiny(3) from perl v5.42.0, dated 2026-01-17 — go forth and compile coderefs from strings responsibly, mwah 💋✨🌸