underscore.txt

*underscore.txt*	underscore.vim

Author  : haya14busa <hayabusa1419@gmail.com>
Version : 1.0.0
License : MIT license {{{

	Copyright (c) 2014 haya14busa

	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.

}}}

CONTENTS				*underscore-contents*

	Introduction			|underscore-introduction|
	Install				|underscore-install|
	Collections			|underscore-Collections|
	Functions			|underscore-Functions|
	Objects				|underscore-Objects|
	Utility				|underscore-Utility|
	Chaining			|underscore-chaining|
	ChangeLog			|underscore-changelog|

==============================================================================
INTRODUCTION					*underscore-introduction*

	*underscore.vim* is a Vim script library that provides a whole mess of
	useful functional programming helpers.

	Its api and documentation are heavily inspired by Underscore.js[1],
	lodash[2] and Underscore.lua[3]. Its implementation is heavily
	inspired by and taken from |vital.vim|[4].

	  [1]: http://underscorejs.org/
	  [2]: https://github.com/lodash/lodash
	  [3]: http://mirven.github.io/underscore.lua/
	  [4]: https://github.com/vim-jp/vital.vim

==============================================================================
INSTALL							*underscore-install*

	1. Install |vital.vim| and |underscore.vim| with your favorite plugin
	manager.
>
		NeoBundle 'vim-jp/vital.vim'
		NeoBundle 'haya14busa/underscore.vim'

		Plugin 'vim-jp/vital.vim'
		Plugin 'haya14busa/underscore.vim'

		Plug 'vim-jp/vital.vim'
		Plug 'haya14busa/underscore.vim'
<
	2. Embed underscore.vim into your plugin with |:Vitalize| (assume
	current directory is the root of your plugin repository).
	See |:Vitalize| for more information. >
	    :Vitalize . --name={plugin_name} Underscore
<
	3. You can update underscore.vim with |:Vitalize|. >
	    :Vitalize .
<
==============================================================================
USAGE							*underscore-usage*

	Import underscore object (`s:_`) like this.
>
	let s:V = vital#of('vital')
	let s:_ = s:V.import('Underscore').import()
<
==============================================================================
COLLECTIONS						*underscore-Collections*

_.each({list}, {func})			*underscore-each* *underscore-for_each*
					*_.each()* *_.for_each()*
	Iterates over a list of elements, yielding each in turn to an iteratee
	function. Returns the {list} for chaining. alias: for_each
>
	function! s:echo(x, ...) abort
	  echo a:x
	endfunction
	function! s:echo_with_count(x, cnt) abort
	  echo a:cnt . ' : ' . a:x
	endfunction

	call s:_.each(['one', 'two', 'three'], function('s:echo'))
	" => echo each number in turn...
	call s:_.each(['one', 'two', 'three'], function('s:echo_with_count'))
	" => echo each number with count in turn...

_.map({list}, {func})			*underscore-map* *underscore-collect*
					*_.map()* *_.collect()*
	Produces a new array of values by mapping each value in list through a
	transformation function. alias: collect
>
	echo s:_.map([1, 2, 3], 'v:val * 3')
	" => [3, 6, 9]

_.reduce({list}, {init}, {func})	*underscore-reduce* *underscore-foldl*
					*underscore-inject*
					*_.reduce()* *_.foldl()* *_.inject()*
	Reduces the list {list} using the binary operator {func}, from left to
	right. The starting value of the reduction (typically the
	left-identity of the operator) is {init}. alias: foldl, inject
>
	function! s:add(x, y) abort
	  return a:x + a:y
	endfunction

	echo s:_.reduce([1, 2, 3], 0, 'v:memo + v:val')
	echo s:_.reduce([1, 2, 3], 0, function('s:add'))
	" => 6

_.reduceRight({list}, {init}, {func})	*underscore-reduceRight*
					*underscore-foldr*
					*_.reduceRight()* *_.foldr()*
	The right-associative version of |_.reduce()|. alias: foldr
>
	let list = [[0, 1], [2, 3], [4, 5]]
	let flat = s:_.reduceRight(list, [], 'v:memo + v:val')
	echo flat
	" => [4, 5, 2, 3, 0, 1]

_.find({list}, {default}, {func})	*underscore-find* *underscore-detect*
					*_.find()* *_.detect()*
	Looks through each value in the {list}, returning the first one that
	passes a truth test ({func} as a predicate), or {default} if no value
	passes the test. The function returns as soon as it finds an
	acceptable element, and doesn't traverse the entire list.
	alias: detect
>
	let even = s:_.find([1, 2, 3, 4, 5, 6], -1, 'v:val % 2 == 0')
	echo even
	" => 2

_.filter({list}, {func})		*underscore-filter* *underscore-select*
					*_.filter()* *_.select()*
	Looks through each value in the {list}, returning an array of all the
	values that pass a truth test ({func} as a predicate). alias: select
>
	let evens = s:_.filter([1, 2, 3, 4, 5, 6], 'v:val % 2 == 0')
	echo evens
	" => [2, 4, 6]

_.reject({list}, {func})		*underscore-reject* *_.reject()*
	Returns the values in {list} without the elements that the truth test
	({func} as a predicate) passes. The opposite of filter.
>
	let odds = s:_.reject([1, 2, 3, 4, 5, 6], 'v:val % 2 == 0')
	echo odds
	" => [1, 3, 5]

_.every({list}, {func})			*underscore-every* *underscore-all*
					*_.every()* *_.all()*
	Returns true if all of the values in the {list} pass the predicate
	({func}) truth test. alias: all
>
	echo s:_.every([2, 4, 6, 7], 'v:val % 2 == 0')
	" => 0
	echo s:_.every([2, 4, 6, 8], 'v:val % 2 == 0')
	" => 1

_.some({list}, {func})			*underscore-some* *underscore-any*
					*_.some()* *_.any()*
	Returns true if any of the values in the {list} pass the
	predicate({func}) truth test. Short-circuits and stops traversing the
	{list} if a true element is found. alias: any
>
	echo s:_.some([2, 4, 6, 7], 'v:val % 2 == 0')
	" => 1
	echo s:_.some([1, 3, 5, 7], 'v:val % 2 == 0')
	" => 0

_.contains({list}, {func})		*underscore-contains* *underscore-include*
					*_.contains()* *_.include()*
	Returns true if the value is present in the {list}. alias: include
>
	echo s:_.contains([1, 2, 3], 3)
	" => 1

_.sort({list} [, {func}])		*underscore-sort* *_.sort()*
	Returns sorted copy of {list}. If {func} is omitted, empty, 0,
	|Funcref|, 'i', or 'n', function returns the same result as |sort()|.
	When {expr} is a |String|, this function uses {expr} to compare items.
	Inside {expr} a:a and a:b have the value of the current items.  The
	evaluating result of {expr} must have zero if they are equal, 1 or
	bigger if a:a sorts after the a:b, -1 or smaller if a:a sorts before
	a:b.
>
	echo s:_.sort([3, 1, 2], 'a:a - a:b')
	" => [1, 2, 3]

_.sort_by({list}, {func})		*underscore-sort_by* *_.sort_by()*
	Returns a sorted copy of {list}, ranked in ascending order by the
	results of running each value in {list} through {func}.
>
	echo s:_.sort_by(['three', 'four', 'five'], function('len'))
	echo s:_.sort_by(['three', 'four', 'five'], 'len(v:val)')
	" => ['four', 'five', 'three']

_.reverse({list})			*underscore-reverse* *_.reverse()*
	Returns a copy of reversed {list}.
>
	echo s:_.reverse([3, 1, 2])
	" => [2, 1, 3]

_.group_by({list}, {func})		*underscore-group_by* *_.group_by()*
	Returns a |Dictionary| grouped by the result of running each value in
	{list} through {func}.
>
	echo s:_.group_by(['one', 'two', 'three'], function('len'))
	echo s:_.group_by(['one', 'two', 'three'], 'len(v:val)')
	" => {'3': ['one', 'two'], '5': ['three']}

_.length({list})			*underscore-length* *underscore-size*
					*_.length()* *_.size()*
	Returns the number of values in the {list}. alias: size
>
	echo s:_.size({'one': 1, 'two': 2, 'three': 3})
	" => 3

_.take({list} [, {n}])	*underscore-take* *underscore-head* *underscore-first*
					*_.take()* *_.head()* *_.first()*
	Returns the first element of a {list}. Passing {n} will return the
	first {n} elements of the {list}.
>
	echo s:_.take([5, 4, 3, 2, 1])
	" => 5
	echo s:_.take([5, 4, 3, 2, 1], 3)
	" => [5, 4, 3]

_.initial({list} [, {n}])		*underscore-initial* *_.initial()*
	Returns everything but the last entry of the {list}. Pass {n} to
	exclude the last {n} elements from the result.
>
	echo s:_.initial([5, 4, 3, 2, 1])
	" => [5, 4, 3, 2]
	echo s:_.initial([5, 4, 3, 2, 1], 2)
	" => [5, 4, 3]

_.last({list} [, {n}])			*underscore-last* *_.last()*
	Returns the last element of a {list}. Passing {n} will return the last
	{n} elements of the {list}.
>
	echo s:_.last([5, 4, 3, 2, 1])
	" => 1
	echo s:_.last([5, 4, 3, 2, 1], 3)
	" => [3, 2, 1]

_.rest({list} [, {index}])	*underscore-rest* *underscore-tail*
				*underscore-drop* *_.rest()* *_.tail()* *_.drop()*
	Returns the rest of the elements in a {list}. Pass an {index} to return
	the values of the {list} from that {index} onward.
>
	echo s:_.rest([5, 4, 3, 2, 1])
	" => [4, 3, 2, 1]
	echo s:_.rest([5, 4, 3, 2, 1], 3)
	" => [2, 1]

_.compact({list})			*underscore-compact* *_.compact()*
	Returns a copy of the {list} with all falsy values removed.
>
	echo s:_.compact([0, 1, 2, 3, '', 'vim'])
	" => [1, 2, 3, 'vim']

_.flatten({list} [, {limit}])		*underscore-flatten* *_.flatten()*
	Flattens a nested {list} (the nesting can be specified with {limit}
	default is to any depth).
>
	echo s:_.flatten([1, [2], [3, [[4]]]])
	" => [1, 2, 3, 4]
	echo s:_.flatten([1, [2], [3, [[4]]]], 2)
	" => [1, 2, 3, [4]]

_.uniq({list})				*underscore-uniq* *underscore-unique*
					*_.uniq()* *_.unique()*
	Produces a duplicate-free version of the {list}. alias: unique
>
	echo s:_.uniq([1, 2, 1, 3, 1, 4])
	" => [1, 2, 3, 4]

_.uniq_by({list}, {func})	*underscore-uniq_by* *underscore-unique_by*
				*_.uniq_by()* *_.unique_by()*
	Produces a duplicate-free version of the {list}. The uniquness is
	judged by the result of {func}. alias: unique_by
>
	echo s:_.uniq_by([4, 2, 3, 1, 4], 'v:val % 2')
	" => [4, 3]

_.zip({list}, ...)			*underscore-zip* *_.zip()*
	Zips given {list}s like python's one.
>
	echo s:_.zip(['a', 'b', 'c'], [1, 2, 3])
	" => [['a', 1], ['b', 2], ['c', 3]]

_.pop({list})				*underscore-pop* *_.pop()*
	Removes the last element from {list} and returns the element.
>
	let xs = ['a', 'b', 'c']
	echo s:_.pop(xs)
	" => 'c'
	echo xs
	" => ['a', 'b']

_.push({list}, {value})			*underscore-push* *_.push()*
	Appends {value} to the end of {list} and returns the list itself.
>
	let xs = ['a', 'b']
	echo s:_.push(xs, 'c')
	" => ['a', 'b', 'c']
	echo xs
	" => ['a', 'b', 'c']

_.shift({list})				*underscore-shift* *_.shift()*
	Removes the first element from {list} and returns the element.
>
	let xs = ['a', 'b', 'c']
	echo s:_.shift(xs)
	" => 'a'
	echo xs
	" => ['b', 'c']

_.unshift({list}, {value})		*underscore-unshift* *_.unshift()*
	Inserts {value} to the head of {list} and returns the list itself.
>
	let xs = ['b', 'c']
	echo s:_.unshift(xs, 'a')
	" => ['a', 'b', 'c']
	echo xs
	" => ['a', 'b', 'c']

==============================================================================
FUNCTIONS						*underscore-Functions*

_.memoize({func} [, {hashfunc}])		*underscore-memoize* *_.memoize()*
	Memoizes a given function by caching the computed result. If passed
	an optional hashFunction, it will be used to compute the hash key for
	storing the result, based on the arguments to the original function.
>
	let s:i = 0
	function! s:_fibo(n) abort
	  let s:i += 1
	  return a:n < 2 ? a:n : s:fibo(a:n-1) + s:fibo(a:n-2)
	endfunction
	let s:fibo = s:_.memoize(function('s:_fibo'))
	echo s:fibo(30) | " => 832040
	echo s:i | " => 31

==============================================================================
OBJECTS							*underscore-Objects*

_.tap({object}, {interceptor})	  		*underscore-tap* *_.tap()*
	Invokes interceptor |Funcref| with the object, and then returns
	object. The primary purpose of this method is to "tap into" a method
	chain, in order to perform operations on intermediate results within
	the chain.
>
	function! s:echo(msg)
	  echo a:msg
	endfunction

	echo s:_.chain([1,2,3,200])
	  \.filter('v:val % 2 == 0')
	  \.tap(function('s:echo'))
	  \.map('v:val * v:val')
	  \.value()
	" => // [2, 200] (echoed)
	" => [4, 40000]

_.is_number({value})			*underscore-is_number* *_.is_number()*
	Returns non-zero if {value} is a |Number|, zero otherwise.

_.is_float({value})			*underscore-is_float* *_.is_float()*
	Returns non-zero if {value} is a |Float|, zero otherwise.

_.is_string({value})			*underscore-is_string* *_.is_string()*
	Returns non-zero if {value} is a String (|string|), zero otherwise.

_.is_funcref({value})			*underscore-is_funcref* *_.is_funcref()*
	Returns non-zero if {value} is a |Funcref|, zero otherwise.

_.is_list({value})			*underscore-is_list* *_.is_list()*
	Returns non-zero if {value} is a |List|, zero otherwise.

_.is_dict({value})			*underscore-is_dict* *_.is_dict()*
	Returns non-zero if {value} is a |Dictionary|, zero otherwise.

_.functions({object})		*underscore-functions* *underscore-methods*
				*_.functions()* *_.methods*
	Returns a list of function names from all {object}. alias: methods
>
	echo s:_.functions(s:_)
	" => ['_', 'all', 'any', 'chain', ...]

==============================================================================
UTILITY							*underscore-Utility*

_.TRUE					*underscore-TRUE* *_.TRUE*
	This is 1 to represent true as boolean like syntax.
>
	echo s:_.TRUE ? 'true' : '' | " => 'true'

_.FALSE					*underscore-FALSE* *_.FALSE*
	This is 0 to represent false as boolean like syntax.
>
	echo s:_.FALSE ? '' : 'false' | " => 'false'

_.identity({value})			*underscore-identity* *_.identity()*
	Returns the same value that is used as the argument
>
	let x = 'a'
	echo x is# s:_.identity(x)
	" => 1

_.mixin({object})			*underscore-mixin* *_.mixin()*
	Allows you to extend Underscore.vim with your own utility functions.
	Pass an object of `{name: funcref}` definitions to have your functions
	added to the Underscore object, as well as the OOP wrapper.
>
	let s:ex = {}
	function! s:ex.capitalize(str)
	  return toupper(a:str[0]) . tolower(a:str[1:])
	endfunction
	function! s:ex.startsWith(str, start)
	  return split(a:str, '\zs')[0] is# a:start
	endfunction
	call s:_.mixin(s:ex)
	echo s:_.capitalize('haya14busa')
	" => 'Haya14busa'
	echo s:_.chain('haya14busa')
	  \.capitalize()
	  \.startsWith('H')
	  \.value()
	" => 1
<
	Even you can extend underscore.vim with other libraries like
	|Vital.Data.String|!
>
	call s:_.mixin(vital#of('vital').import('Data.String'))
	echo s:_.chain("  haya14busa  \n")
	  \.chomp()
	  \.trim()
	  \.pad_left(14, '#')
	  \.value()
	" => '####haya14busa'

==============================================================================
CHAINING				 *underscore-chaining*
	You can use underscore.vim in either an object-oriented or a
	functional style, depending on your preference. The following two
	lines of code are identical ways to double a list of numbers.
>
	echo s:_.map([1, 2, 3],   'v:val * 2')
	echo s:_._([1, 2, 3]).map('v:val * 2')
	" => [2, 4, 6]
<
	Calling |_.chain()| will cause all future method calls to return
	wrapped underscore objects.  When you've finished the computation,
	call |_(obj).value()| to retrieve the final value.

_.chain({value})			*underscore-chain* *_.chain()*
	Creates an wrapped underscore object that wraps value with explicit
	method chaining enabled. Calling methods on this object will continue
	to return wrapped underscore objects until |_(obj).value()| is called.
>
	let users = [
	\  { 'user': 'barney',  'age': 36 },
	\  { 'user': 'fred',    'age': 40 },
	\  { 'user': 'pebbles', 'age': 1 }
	\]

	echo s:_.chain(users)
	  \.sort_by('v:val.age')
	  \.map('v:val.user . " is " . v:val.age')
	  \.first()
	  \.value()
	" => pebbles is 1

	function! s:toFizzBuzz(x)
	  return a:x%15 ? a:x%3 ? a:x%5 ? a:x : 'Buzz' : 'Fizz' : 'FizzBuzz'
	endfunction

	echo s:_._(range(20))
	  \.chain()
	  \.map('v:val + 1')
	  \.filter('v:val % 2')
	  \.map(function('s:toFizzBuzz'))
	  \.value()
	" [1, 'Fizz', 'Buzz', 7, 'Fizz', 11, 13, 'FizzBuzz', 17, 19]

_(obj).value()				*underscore-value* *_(obj).value()*
	Extracts the value of a wrapped underscore object.

_._({value})				*underscore-_* *_._()*
	Creates a wrapped underscore object which wraps value to enable
	implicit chaining.
>
	echo s:_._(range(1, 10)).reduce(0, 'v:memo + v:val')
	" => 55
	echo s:_._(range(10)).filter('v:val % 2 == 0')
	" => [0, 2, 4, 6, 8]

==============================================================================
CHANGELOG						*underscore-changelog*

1.0.0	2015-04-01
	- Init.


vim:tw=78:ts=8:ft=help:norl:noet:fen:fdl=0:fdm=marker: