One recurring problem in modules that use Scalar::Util's weaken function is that it is not present in the pure-perl variant. If Scalar::Util is not available at all, it will issue a normal dependency on the module. However, if Scalar::Util is relatively new ( it is >= 1.19 ) and the module does not have weaken, the install will bail out altogether with a long error encouraging the user to seek support.

This module replaces the standard localtime and gmtime functions with implementations that return objects. It does so in a backwards-compatible manner, so that using these functions as documented will still work as expected.

Calling Perl's in-built system function is easy, determining if it was successful is hard. Let's face it, $? isn't the nicest variable in the world to play with, and even if you do check it, producing a well-formatted error string takes a lot of work.

IPC::System::Simple takes the hard work out of calling external commands.

Text::Table renders plaintext tables.

Data::Dumper::Concise provides a dumper with Less indentation and newlines plus sub deparsing.

Getopt::Long::Descriptive is yet another Getopt library. It's built atop Getopt::Long, and gets a lot of its features, but tries to avoid making you think about its huge array of options. It also provides usage (help) messages, data validation, and a few other useful features.

This module verifies if requirements described in a CPAN::Meta object are present.

Moo is an extremely light-weight Object Orientation system. It allows one to concisely define objects and roles with a convenient syntax that avoids the details of Perl's object system. Moo contains a subset of Moose and is optimised for rapid startup.

File::Zglob provides a traditional Unix glob functionality; it returns a list of file names that match the given pattern. For instance, it supports the **/*.pm form.

Date::Range is a library to work with date ranges. It can be used to determine whether a given date is in a particular range, or what the overlap between two ranges are.

This module provides lexicon-handling modules to read from other localization formats, such as Gettext, Msgcat, and so on.

This module exports a single function: ttie. It ties a variable to a type constraint, ensuring that whatever values stored in the variable will conform to the type constraint. If the type constraint has coercions, these will be used if necessary to ensure values assigned to the variable conform.

Modern::Perl provides a simple way to enable multiple, by now, standard libraries in a Perl program.

Date::Manip is a series of modules for common date/time operations, such as comparing two times, determining a date a given amount of time from another, or parsing international times.

This package provides the IO::Pty and IO::Tty Perl interfaces to pseudo ttys.

Devel::OverloadInfo returns information about overloaded operators for a given class (or object), including where in the inheritance hierarchy the overloads are declared and where the code implementing it is.

The File::List module crawls the directory tree starting at the provided base directory and can return files (and/or directories if desired) matching a regular expression.

It's boring to deal with opening files for IO, converting strings to handle-like objects, and all that. With Mixin::Linewise::Readers and Mixin::Linewise::Writers, you can just write a method to handle handles, and methods for handling strings and file names are added for you.

Perl::MinimumVersion takes Perl source code and calculates the minimum version of perl required to be able to run it. Because it is based on the PPI (Perl Parsing Interface), it can do this without loading the code. The distribution comes with a script called perlver.

The Template Toolkit is a collection of modules which implement an extensible template processing system. It was originally designed and remains primarily useful for generating dynamic web content, but it can be used equally well for processing any other kind of text based documents: HTML, XML, POD, PostScript, LaTeX, and so on.

MooseX::MarkAsMethods allows one to easily mark certain functions as Moose methods. This will allow other packages such as namespace::autoclean to operate without blowing away your overloads. After using MooseX::MarkAsMethods your overloads will be recognized by Class::MOP as being methods, and class extension as well as composition from roles with overloads will "just work".

This module is intended to easily load initialization values for attributes on object construction from an appropriate config file. The building is done in MooX::ConfigFromFile::Role---using MooX::ConfigFromFile ensures that the role is applied.

This class is the base class for all time zone objects. A time zone is represented internally as a set of observances, each of which describes the offset from GMT for a given time period. Note that without the DateTime module, this module does not do much. It's primary interface is through a DateTime object, and most users will not need to directly use DateTime::TimeZone methods.

Chaolin Zhang's Perl Library (czplib) contains assorted functions and data structures for processing and analysing genomic and bioinformatics data.