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Sah-SchemaBundle-Array-0.004
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/ Sah::Schema::array::num::monotonically_decreasing

NAME

Sah::Schema::array::num::monotonically_decreasing - An array of numbers with monotonically decreasing elements

VERSION

This document describes version 0.004 of Sah::Schema::array::num::monotonically_decreasing (from Perl distribution Sah-SchemaBundle-Array), released on 2024-02-13.

SAH SCHEMA DEFINITION

[
  "array",
  {
    summary => "An array of numbers with monotonically decreasing elements",
    prefilters => ["Array::check_elems_numeric_monotonically_decreasing"],
    of => ["num", { req => 1 }],
  },
]

Base type: array

Used prefilters: Array::check_elems_numeric_monotonically_decreasing

SYNOPSIS

Sample data and validation results against this schema

{}  # INVALID (Not an array)

[]  # valid

[1,"a"]  # INVALID (Contains a non-numeric element)

[1,undef]  # INVALID (Contains an undefined element)

[3,2,2,1]  # INVALID (Duplicate elements)

[1,2,3]  # INVALID (Not monotonically decreasing)

[1,3,2]  # INVALID (Not monotonically decreasing)

[3,2.9,1]  # valid

Using with Data::Sah

To check data against this schema (requires Data::Sah):

use Data::Sah qw(gen_validator);
my $validator = gen_validator("array::num::monotonically_decreasing*");
say $validator->($data) ? "valid" : "INVALID!";

The above validator returns a boolean result (true if data is valid, false if otherwise). To return an error message string instead (empty string if data is valid, a non-empty error message otherwise):

my $validator = gen_validator("array::num::monotonically_decreasing", {return_type=>'str_errmsg'});
my $errmsg = $validator->($data);

# a sample valid data
$data = [3,2.9,1];
my $errmsg = $validator->($data); # => ""

# a sample invalid data
$data = [1,"a"];
my $errmsg = $validator->($data); # => "\@[1]: Not of type number"

Often a schema has coercion rule or default value rules, so after validation the validated value will be different from the original. To return the validated (set-as-default, coerced, prefiltered) value:

my $validator = gen_validator("array::num::monotonically_decreasing", {return_type=>'str_errmsg+val'});
my $res = $validator->($data); # [$errmsg, $validated_val]

# a sample valid data
$data = [3,2.9,1];
my $res = $validator->($data); # => ["",[3,2.9,1]]

# a sample invalid data
$data = [1,"a"];
my $res = $validator->($data); # => ["\@[1]: Not of type number",[1,"a"]]

Data::Sah can also create validator that returns a hash of detailed error message. Data::Sah can even create validator that targets other language, like JavaScript, from the same schema. Other things Data::Sah can do: show source code for validator, generate a validator code with debug comments and/or log statements, generate human text from schema. See its documentation for more details.

Using with Params::Sah

To validate function parameters against this schema (requires Params::Sah):

use Params::Sah qw(gen_validator);

sub myfunc {
    my @args = @_;
    state $validator = gen_validator("array::num::monotonically_decreasing*");
    $validator->(\@args);
    ...
}

Using with Perinci::CmdLine::Lite

To specify schema in Rinci function metadata and use the metadata with Perinci::CmdLine (Perinci::CmdLine::Lite) to create a CLI:

# in lib/MyApp.pm
package
  MyApp;
our %SPEC;
$SPEC{myfunc} = {
    v => 1.1,
    summary => 'Routine to do blah ...',
    args => {
        arg1 => {
            summary => 'The blah blah argument',
            schema => ['array::num::monotonically_decreasing*'],
        },
        ...
    },
};
sub myfunc {
    my %args = @_;
    ...
}
1;

# in myapp.pl
package
  main;
use Perinci::CmdLine::Any;
Perinci::CmdLine::Any->new(url=>'/MyApp/myfunc')->run;

# in command-line
% ./myapp.pl --help
myapp - Routine to do blah ...
...

% ./myapp.pl --version

% ./myapp.pl --arg1 ...

Using on the CLI with validate-with-sah

To validate some data on the CLI, you can use validate-with-sah utility. Specify the schema as the first argument (encoded in Perl syntax) and the data to validate as the second argument (encoded in Perl syntax):

% validate-with-sah '"array::num::monotonically_decreasing*"' '"data..."'

validate-with-sah has several options for, e.g. validating multiple data, showing the generated validator code (Perl/JavaScript/etc), or loading schema/data from file. See its manpage for more details.

Using with Type::Tiny

To create a type constraint and type library from a schema (requires Type::Tiny as well as Type::FromSah):

package My::Types {
    use Type::Library -base;
    use Type::FromSah qw( sah2type );

    __PACKAGE__->add_type(
        sah2type('array::num::monotonically_decreasing*', name=>'ArrayNumMonotonicallyDecreasing')
    );
}

use My::Types qw(ArrayNumMonotonicallyDecreasing);
ArrayNumMonotonicallyDecreasing->assert_valid($data);

DESCRIPTION

Use this schema if you want to accept an array of numbers where the elements are monotonically decreasing, i.e. elem(i) < elem(i-1) for all i > 0. It's similar to the array::num::reverse_sorted schema except that duplicate numbers are not allowed (e.g. [4, 2, 2, 1] is okay for array::num::reverse_sorted but will fail array::num::monotonically_decreasing).

HOMEPAGE

Please visit the project's homepage at https://metacpan.org/release/Sah-SchemaBundle-Array.

SOURCE

Source repository is at https://github.com/perlancar/perl-Sah-SchemaBundle-Array.

AUTHOR

perlancar <perlancar@cpan.org>

CONTRIBUTING

To contribute, you can send patches by email/via RT, or send pull requests on GitHub.

Most of the time, you don't need to build the distribution yourself. You can simply modify the code, then test via:

% prove -l

If you want to build the distribution (e.g. to try to install it locally on your system), you can install Dist::Zilla, Dist::Zilla::PluginBundle::Author::PERLANCAR, Pod::Weaver::PluginBundle::Author::PERLANCAR, and sometimes one or two other Dist::Zilla- and/or Pod::Weaver plugins. Any additional steps required beyond that are considered a bug and can be reported to me.

COPYRIGHT AND LICENSE

This software is copyright (c) 2024, 2023 by perlancar <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.

BUGS

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

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.