Sub::Fp - A Clojure / Python Toolz / Lodash inspired Functional Utility Library
This library provides numerous functional programming utility methods, as well as functional varients of native in-built methods, to allow for consistent, concise code.
incr reduces flatten drop_right drop take_right take assoc maps decr chain first end subarray partial __ find filter some none uniq bool spread every len is_array is_hash to_keys to_vals noop identity is_empty flow eql is_sub to_pairs for_each apply get second
Increments the supplied number by 1
incr(1) # => 2
Decrements the supplied number by 1
decr(2) # => 1
Creates a function that is restricted to invoking func once. Repeat calls to the function return the value of the first invocation.
my $times_called = 0; my $sub = once(sub { $times_called++; return "I was only called $times_called time" }); $sub->(); # "I was only called 1 time" $sub->(); # "I was only called 1 time" $sub->(); # etc
Calls the supplied function with the array of arguments, spreading the arguments into the function it invokes
my $sum_all_nums = sub { my $num = shift; my $second_num = shift; return $num + $second_num; }; apply($sum_all_nums, [100, 200]); # same as $sum_all_nums->(100, 200) # => 300
Creates an array of numbers (positive and/or negative) progressing from start up to, but not including, end. A step of -1 is used if a negative start is specified without an end or step. If end is not specified, it's set to start with start then set to 0.
range(10); # [1,2,3,4,5,6,7,8,9] range(1,10); # [1,2,3,4,5,6,7,8,9] range(-1, -10); # [-1, -2, -3, -4, -5, -6 ,-7, -8, -9] range(1, 4, 0); # [1, 1, 1] #Ranges that "dont make sense" will return empty arrays range(-1, -4, 0); # [] range(100, 1, 0) # [] range(0,0,0) # [] range(0, -100, 100) # [] range(0, 100, -100) # [] #etc...
Iterates over elements of collection and invokes iteratee for each element. The iteratee is invoked with three arguments: (value, index|key, collection).
for_each(sub { my $num = shift; print $num; }, [1,2,3]); for_each(sub { my ($num, $idx, $coll) = @_; print $idx; }, [1,2,3]) # 0 1 2 for_each(sub { my ($num, $idx, $coll) = @_; print Dumper $coll; }, [1,2,3]) # [1,2,3], # [1,2,3], # [1,2,3]
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 $num + 1; }, [1,1,1]); # [2,2,2]
Reduces collection to a value which is the accumulated result of running each element in collection thru iteratee, where each successive invocation is supplied the return value of the previous. If accumulator is not given, the first element of collection is used as the initial value. The iteratee is invoked with four arguments: (accumulator, value, index|key, collection).
# Implicit Accumulator reduces(sub { my ($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, # }
Flattens array a single level deep.
flatten([1,1,1, [2,2,2]]); # [1,1,1,2,2,2];
Works the same as builtin pop / push etc etc, with mutations, except it uses references instead of @ lists.
my $array = [1,2,3]; pops($array) # 3 my $array = [1,2,3]; pushes($array, 4); # [1,2,3,4]
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]
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]
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]); # []
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]); # []
Returns the second item in an array
second(["I", "am", "a", "string"]) # "am" second([5,4,3,2,1]) # 4
Returns the first item in an array
first(["I", "am", "a", "string"]) # "I" first([5,4,3,2,1]) # 5
Returns the end, or last item in an array
end(["I", "am", "a", "string"]) # "string" end([5,4,3,2,1]) # 1
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([]) # 0
A function that does nothing (like our government), and returns undef
noop() # undef
A function that returns its first argument
identity() # undef identity(1) # 1 identity([1,2,3]) # [1,2,3]
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'
Returns 0 or 1 if the argument is a sub ref
is_sub() # 0 is_sub(sub {}) # 1 my $sub = sub {}; is_sub($sub) # 1
Returns 0 or 1 if the argument is an array
is_array() # 0 is_array([1,2,3]) # 1
Returns 0 or 1 if the argument is a hash
is_hash() # 0 is_hash({ key => 'val' }) # 1
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") # 0
Returns value from hash, string, array based on key/idx provided. Returns default value if provided key/idx does not exist on collection. Only works one level deep;
my $hash = { key1 => 'value1', }; get($hash, 'key1'); # 'value1' my $array = [100, 200, 300] get($array, 1); # 200 my $string = "Hello"; get($string, 1); # e # Also has the ability to supply default-value when key/idx does not exist my $hash = { key1 => 'value1', }; get($hash, 'key2', "DEFAULT HERE"); # 'DEFAULT HERE'
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'
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) # 0
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];
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'];
Creates an array of key-value, or idx-value pairs from arrays, hashes, and strings. If used on a hash, key-pair order can not be guaranteed;
to_pairs("I am a string"); # [ # [0, "I"], # [1, "am"], # [2, "a"], # [3, "string"] # ] to_pairs([100, 101, 102]); # [ # [0, 100], # [1, 102], # [2, 103], # ] to_pairs({ key1 => 'value1', key2 => 'value2' }); # [ # [key1, 'value1'], # [key2, 'value2'] # ] to_pairs({ key1 => 'value1', key2 => { nested => 'nestedValue' }}); # [ # [key1, 'value1'], # [key2, { nested => 'nestedValue' }] # ]
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"]
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}
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"]
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 }
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, # } # ]
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
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
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
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"
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]
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); # 3
Kristopher C. Paulsen, <kristopherpaulsen+cpan at gmail.com>
<kristopherpaulsen+cpan at gmail.com>
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.
bug-sub-fp at rt.cpan.org
You can find documentation for this module with the perldoc command.
perldoc Sub::Fp
You can also look for information at:
RT: CPAN's request tracker (report bugs here)
https://rt.cpan.org/NoAuth/Bugs.html?Dist=Sub-Fp
AnnoCPAN: Annotated CPAN documentation
http://annocpan.org/dist/Sub-Fp
CPAN Ratings
https://cpanratings.perl.org/d/Sub-Fp
Search CPAN
https://metacpan.org/release/Sub-Fp
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.
To install Sub::Fp, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Sub::Fp
CPAN shell
perl -MCPAN -e shell install Sub::Fp
For more information on module installation, please visit the detailed CPAN module installation guide.