NAME
Sub::Fp - A Clojure / Python Toolz / Lodash inspired Functional Utility Library
SYNOPSIS
This library provides numerous functional programming utility methods, as well as functional varients of native in-built methods, to allow for consistent, concise code.
SUBROUTINES/METHODS
EXPORT
incr reduces flatten
drop_right drop take_right take
assoc maps decr chain
first end subarray partial
__ find filter some
none uniq bool spread
len to_keys to_vals is_array
is_hash every noop identity
flow eqlincr
Increments the supplied number by 1
incr(1)
# => 2decr
Decrements the supplied number by 1
decr(2)
# => 1maps
Creates an array of values by running each element in collection thru iteratee. The iteratee is invoked with three arguments: (value, index|key, collection).
maps(sub {
my $num = shift;
return $num + 1;
}, [1,1,1]);
# [2,2,2]reduces
Reduces collection to a value which is the accumulated result of running each element in collection thru iteratee, where each successive invocation is supplied the return value of the previous. If accumulator is not given, the first element of collection is used as the initial value. The iteratee is invoked with four arguments: (accumulator, value, index|key, collection).
# Implicit Accumulator
reduces(sub {
my ($sum, $num) = @_;
return $sum + $num;
}, [1,1,1]);
# 3
# Explict Accumulator
reduces(sub {
my ($accum, $num) = @_;
return {
spread($accum),
key => $num,
}
}, {}, [1,2,3]);
# {
# key => 1,
# key => 2,
# key => 3,
# }flatten
Flattens array a single level deep.
flatten([1,1,1, [2,2,2]]);
# [1,1,1,2,2,2];drop
Creates a slice of array with n elements dropped from the beginning.
drop([1,2,3])
# [2,3];
drop(2, [1,2,3])
# [3]
drop(5, [1,2,3])
# []
drop(0, [1,2,3])
# [1,2,3]drop_right
Creates a slice of array with n elements dropped from the end.
drop_right([1,2,3]);
# [1,2]
drop_right(2, [1,2,3])
# [1]
drop_right(5, [1,2,3])
# []
drop_right(0, [1,2,3])
#[1,2,3]take
Creates a slice of array with n elements taken from the beginning.
take([1, 2, 3);
# [1]
take(2, [1, 2, 3]);
# [1, 2]
take(5, [1, 2, 3]);
# [1, 2, 3]
take(0, [1, 2, 3]);
# []take_right
Creates a slice of array with n elements taken from the end.
take_right([1, 2, 3]);
# [3]
take_right(2, [1, 2, 3]);
# [2, 3]
take_right(5, [1, 2, 3]);
# [1, 2, 3]
take_right(0, [1, 2, 3]);
# []first
Returns the first item in an array
first(["I", "am", "a", "string"])
# "I"
first([5,4,3,2,1])
# 5end
Returns the end, or last item in an array
end(["I", "am", "a", "string"])
# "string"
end([5,4,3,2,1])
# 1len
Returns the length of the collection. If an array, returns the number of items. If a hash, the number of key-val pairs. If a string, the number of chars (following built-in split)
len([1,2,3,4])
# 4
len("Hello")
# 5
len({ key => 'val', key2 => 'val'})
#2
len([])
# 0noop
A function that does nothing (like our government), and returns undef
noop()
# undefidentity
A function that returns its first argument
identity()
# undef
identity(1)
# 1
identity([1,2,3])
# [1,2,3]eql
Returns 0 or 1 if the two values have == equality, with convience wrapping for different types (no need to use eq vs ==). Follows internal perl rules on equality following strings vs numbers in perl.
eql([], [])
# 1
eql(1,1)
# 1
my $obj = {};
eql($obj, $obj);
# 1
eql("123", 123)
# 1 'Following perls internal rules on comparing scalars'
eql({ key => 'val' }, {key => 'val'});
# 0 'Only identity equality'is_sub
Returns 0 or 1 if the argument is a sub ref
is_sub()
# 0
is_sub(sub {})
# 1
my $sub = sub {};
is_sub($sub)
# 1is_array
Returns 0 or 1 if the argument is an array
is_array()
# 0
is_array([1,2,3])
# 1is_hash
Returns 0 or 1 if the argument is a hash
is_hash()
# 0
is_hash({ key => 'val' })
# 1is_empty
Returns 1 if the argument is 'empty', 0 if not empty. Used on strings, arrays, hashes.
is_empty()
# 1
is_empty([])
# 1
is_empty([1,2,3])
# 0
is_empty({ key => 'val' })
# 0
is_empty("I am a string")
# 0spread
Destructures an array / hash into non-ref context. Destructures a string into an array of chars (following in-built split)
spread([1,2,3,4])
# 1,2,3,4
spread({ key => 'val' })
# key,'val'
spread("Hello")
# 'H','e','l','l','o'bool
Returns 0 or 1 based on truthiness of argument, following internal perl rules based on ternary coercion
bool([])
# 1
bool("hello!")
# 1
bool()
# 0
bool(undef)
# 0to_keys
Creates an array of the key names in a hash, indicies of an array, or chars in a string
to_keys([1,2,3])
# [0,1,2]
to_keys({ key => 'val', key2 => 'val2' })
# ['key', 'key2']
to_keys("Hey")
# [0, 1, 2];to_vals
Creates an array of the values in a hash, of an array, or string.
to_vals([1,2,3])
# [0,1,2]
to_vals({ key => 'val', key2 => 'val2' })
# ['val', 'val2']
to_vals("Hey");
# ['H','e','y'];uniq
Creates a duplicate-free version of an array, in which only the first occurrence of each element is kept. The order of result values is determined by the order they occur in the array.
uniq([2,1,2])
# [2,1]
uniq(["Hi", "Howdy", "Hi"])
# ["Hi", "Howdy"]assoc
Returns new hash, or array, with the updated value at index / key. Shallow updates only
assoc([1,2,3,4,5,6,7], 0, "item")
# ["item",2,3,4,5,6,7]
assoc({ name => 'sally', age => 26}, 'name', 'jimmy')
# { name => 'jimmy', age => 26}subarray
Returns a subset of the original array, based on start index (inclusive) and end idx (not-inclusive)
subarray(["first", "second", "third", "fourth"], 0,2)
# ["first", "second"]find
Iterates over elements of collection, returning the first element predicate returns truthy for.
my $people = [
{
name => 'john',
age => 25,
},
{
name => 'Sally',
age => 25,
}
]
find(sub {
my $person = shift;
return eql($person->{'name'}, 'sally')
}, $people);
# { name => 'sally', age => 25 }
# find also supports 'iteratee object shorthand'
my $people = [
{
name => 'john',
age => 25,
favorite_food => 'broccoli',
},
{
name => 'Sally',
age => 25,
favorite_food => 'oranges',
},
{
name => 'Old Greg',
age => 100,
favorite_food => 'you do not want to know,
}
]
find({ favorite_food => 'broccoli' }, $people);
# [
# {
# name => 'Sally',
# age => 25,
# favorite_food => 'broccoli',
# },
# ]filter
Iterates over elements of collection, returning only elements the predicate returns truthy for.
my $people = [
{
name => 'john',
age => 25,
},
{
name => 'Sally',
age => 25,
},
{
name => 'Old Greg',
age => 100,
}
]
filter(sub {
my $person = shift;
return $person->{'age'} < 30;
}, $people);
# [
# {
# name => 'john',
# age => 25,
# },
# {
# name => 'Sally',
# age => 25,
# }
# ]
# Filter also supports 'iteratee object shorthand'
filter({ name => 'John' }, $people);
# [
# {
# name => 'john',
# age => 25,
# },
# ]none
If one element is found to return truthy for the given predicate, none returns 0
my $people = [
{
name => 'john',
age => 25,
},
{
name => 'Sally',
age => 25,
},
{
name => 'Old Greg',
age => 100,
}
]
none(sub {
my $person = shift;
return $person->{'age'} > 99;
}, $people);
# 0
none(sub {
my $person = shift;
return $person->{'age'} > 101;
}, $people);
# 1
# none also supports 'iteratee object shorthand'
none({ name => 'Black Bart' }, $people);
# 1every
Itterates through each element in the collection, and checks if element makes predicate return truthy. If all elements cause predicate to return truthy, every returns 1;
every(sub {
my $num = shift;
$num > 0;
}, [1,2,3,4]);
# 1
every(sub {
my $num = shift;
$num > 2;
}, [1,2,3,4]);
# 0
# every also supports 'iteratee object shorthand'
my $people = [
{
name => 'john',
age => 25,
favorite_food => 'broccoli',
},
{
name => 'Sally',
age => 25,
favorite_food => 'broccoli',
},
{
name => 'Old Greg',
age => 100,
favorite_food => 'you do not want to know,
}
]
every({ favorite_food => 'broccoli' }, $people)
# 0some
Checks if predicate returns truthy for any element of collection. Iteration is stopped once predicate returns truthy.
some(sub {
my $num = shift;
$num > 0;
}, [1,2,3,4]);
# 1
some(sub {
my $num = shift;
$num > 2;
}, [1,2,3,4]);
# 1
# some also supports 'iteratee object shorthand'
my $people = [
{
name => 'john',
age => 25,
favorite_food => 'broccoli',
},
{
name => 'Sally',
age => 25,
favorite_food => 'broccoli',
},
{
name => 'Old Greg',
age => 100,
favorite_food => 'you do not want to know,
}
]
some({ favorite_food => 'broccoli' }, $people)
# 1partial
Creates a function that invokes func with partials prepended to the arguments it receives. (funcRef, args)
my $add_three_nums = sub {
my ($a, $b, $c) = @_;
return $a + $b + $c;
};
my $add_two_nums = partial($add_three_nums, 1);
$add_two_nums->(1,1)
# 3
# Can also use __ to act as a placeholder
my $add_four_strings = sub {
my ($a, $b, $c, $d) = @_;
return $a . $b . $c . $d;
};
my $add_two_strings = partial($add_four_strings, "first ", __, "third ", __);
$add_two_strings->("second ", "third ")
# "first second third fourth"chain
Composes functions, left to right, and invokes them, returning the result. Accepts an expression as the first argument, to be passed as the first argument to the proceding function
chain(
[1,2,3, [4,5,6]],
sub {
my $array = shift;
return [spread($array), 7]
},
\&flatten,
);
# [1,2,3,4,5,6,7]
# Invokes first function, and uses that as start value for next func
chain(
sub { [1,2,3, [4,5,6]] },
sub {
my $array = shift;
return [spread($array), 7]
},
\&flatten,
)
# [1,2,3,4,5,6,7]flow
Creates a function that returns the result of invoking the given functions, where each successive invocation is supplied the return value of the previous.
my $addTwo = flow(\&incr, \&incr);
$addTwo->(1);
# 3AUTHOR
Kristopher C. Paulsen, <kristopherpaulsen+cpan at gmail.com>
BUGS
Please report any bugs or feature requests to bug-sub-fp at rt.cpan.org, or through the web interface at https://rt.cpan.org/NoAuth/ReportBug.html?Queue=Sub-Fp. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.
SUPPORT
You can find documentation for this module with the perldoc command.
perldoc Sub::FpYou can also look for information at:
RT: CPAN's request tracker (report bugs here)
AnnoCPAN: Annotated CPAN documentation
CPAN Ratings
Search CPAN
ACKNOWLEDGEMENTS
LICENSE AND COPYRIGHT
MIT
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.