NAME

perleasyfail - A collection of cases where core Perl fails its "easy things should be easy" mantra (plus their remedies)

VERSION

This document describes version 0.000001 of perleasyfail (from Perl distribution perleasyfail), released on 2021-05-26.

DESCRIPTION

Early release.

ARY (Arrays)

ARY/IDENTIFY/1 (Check if something is an array)

JavaScript:

 foo instanceof Array
 Array.isArray(foo)

PHP:

 is_array($foo)

Python:

 type(foo) is list
 isinstance(foo, list)

Ruby:

 foo.kind_of? Array

Perl:

 ref($foo) eq 'ARRAY'

The Perl version is not so bad brevity-wise, but: 1) a typo in 'ARRAY' will not be caught in compile-time; 2) it's slower; 3) it fails to recognize blessed array or tied array.

Perl alternative #1:

 use Scalar::Util qw(reftype);
 reftype($foo) eq 'ARRAY'

This can handle blessed array.

Perl alternative #2:

 use Ref::Util qw(is_arrayref);
 is_arrayref($foo);

This can handle blessed array.

ARY/FINDELEM/1 (Check whether an item is in an array)

JavaScript:

 ary.includes(value)

PHP:

 in_array($value, $ary)
 in_array($value, $ary, $strict)  # also check types, so 123 will not match "123"

Python:

 element in list

Ruby:

 ary.include? value

Perl:

 grep { $_ eq 'value' } @ary  # for string comparison
 grep { $_ ==  value  } @ary  # for numeric comparison

This is one of the cases where strongly-typed languages have an advantage because the user does not need to explicitly specify the operator to use. Perl has multiple equality operators and the user needs to specify which one she wants because the scalar can both be a number of a string.

True, the Perl's grep version is more flexible, but we're talking about easy things here. Plus there's another problem with grep: it does not short-circuit. If you have a million-element array and the value you want is found in the first element, Perl will still continue to the end of the array.

Alternative #1:

 use List::Util qw(first);
 first { $_ eq 'value' } @ary

This solution solves the non-short-circuiting problem, but does not provide syntax brevity.

Alternative #2:

 use List::Util::Find qw(hasnum hasstr);
 hasnum $num, @ary;
 hasstr $str, @ary;

HASH (Hashes)

HASH/IDENTIFY/1 (Check if something is a hash)

PHP:

 is_array($foo)     # in PHP, associate array is still an array

Python:

 type(foo) is dict
 isinstance(foo, dict)

Ruby:

 foo.kind_of? Hash

Perl:

 ref($foo) eq 'HASH'

The Perl version is not so bad brevity-wise, but: 1) a typo in 'HASH' will not be caught in compile-time; 2) it's slower; 3) it fails to recognize blessed hash or tied hash.

Alternative #1:

 use Scalar::Util qw(reftype);
 reftype($foo) eq 'HASH'

This can handle blessed hash.

Alternative #2:

 use Ref::Util qw(is_hashref);
 is_hashref($foo);

This can handle blessed hash.

HOMEPAGE

Please visit the project's homepage at https://metacpan.org/release/perleasyfail.

SOURCE

Source repository is at https://github.com/perlancar/perl-perleasyfail.

BUGS

Please report any bugs or feature requests on the bugtracker website https://rt.cpan.org/Public/Dist/Display.html?Name=perleasyfail

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.

AUTHOR

perlancar <perlancar@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2021 by perlancar@cpan.org.

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

cpanm perleasyfail

perl -MCPAN -e shell
install perleasyfail