Dollar.$wift

Dollar is a Swift library that provides useful functional programming helper methods without extending any built in objects. It is similar to Lo-Dash or Underscore in Javascript.

Setup

Include the Dollar.swift into your project and import the library using import Dollar

Currently there are issues loading the library using pod 'Dollar', '~> 0.2'

Usage

Array Methods

Method	Usage
`$.at`	Creates an array of elements from the specified indexes, or keys, of the collection. Indexes may be specified as individual arguments or as arrays of indexes.
`$.compact`	Creates an array with all nil values removed.
`$.contains`	Checks if a given value is present in the array.
`$.difference`	Creates an array excluding all values of the provided arrays
`$.every`	Checks if the given callback returns true value for all items in the array.
`$.find`	Iterates over elements of an array and returning the first element that the callback returns true for.
`$.findIndex`	This method is like find except that it returns the index of the first element that passes the callback check.
`$.findLastIndex`	This method is like findIndex except that it iterates over elements of the array from right to left.
`$.first`	Gets the first element in the array.
`$.flatten`	Flattens a nested array of any depth.
`$.frequencies`	This method returns a dictionary of values in an array mapping to the total number of occurrences in the array. If passed a function it returns a frequency table of the results of the given function on the arrays elements.
`$.indexOf`	Gets the index at which the first occurrence of value is found.
`$.initial`	Gets all but the last element or last n elements of an array.
`$.intersection`	Creates an array of unique values present in all provided arrays.
`$.join`	Joins the elements in the array to create a concatenated element of the same type.
`$.last`	Gets the last element from the array.
`$.lastIndexOf`	Gets the index at which the last occurrence of value is found.
`$.rest`	The opposite of initial this method gets all but the first element or first n elements of an array.
`$.noop`	A no-operation function.
`$.max`	Retrieves the maximum value in an array.
`$.merge`	Creates an array of all values, including duplicates, of the arrays in the order they are provided.
`$.min`	Retrieves the minimum value in an array.
`$.pluck`	Retrieves the value of a specified property from all elements in the array.
`$.pull`	Removes all provided values from the given array.
`$.range`	Creates an array of numbers (positive and/or negative) progressing from start up to but not including end.
`$.sequence`	Creates an array of an arbitrary sequence. Especially useful with builtin ranges.
`$.remove`	Removes all elements from an array that the callback returns true.
`$.slice`	Slices the array based on the start and end position. If an end position is not specified it will slice till the end of the array.
`$.sortedIndex`	Gives the smallest index at which a value should be inserted into a given the array is sorted.
`$.union`	Creates an array of unique values, in order, of the provided arrays.
`$.uniq`	Creates a duplicate-value-free version of an array.
`$.without`	Creates an array excluding all provided values.
`$.xor`	Creates an array that is the symmetric difference of the provided arrays.
`$.zip`	Creates an array of grouped elements, the first of which contains the first elements of the given arrays.
`$.zipObject`	Creates an object composed from arrays of keys and values.
`$.partition`	Produces an array of arrays, each containing n elements, each offset by step. Stops after a partition is less than n length.
`$.partitionAll`	Produces an array of arrays, each containing n elements, each offset by step. Continues after a partition is less than n length.
`$.partitionBy`	Applies a function to each element in array, splitting it each time the function returns a new value.

Dictionary Methods

Method	Usage
`$.keys`	Creates an array of keys given a dictionary.
`$.values`	Creates an array of values given a dictionary
`$.merge`	Merges all of the dictionaries together and the latter dictionary overrides the value at a given key
`$.pick`	Creates a shallow clone of a dictionary composed of the specified keys.
`$.omit`	Creates a shallow clone of a dictionary excluding the specified keys.

Object Methods

Method	Usage
`$.tap`	Invokes interceptor with the object and then returns object.

Function Methods

Method	Usage
`$.after`	Creates a function that executes passed function only after being called n times.
`$.bind`	Creates a function that, when called, invokes func with the binding of arguments provided.
`$.id`	The identify function which simply returns the argument its given.
`$.partial`	Creates a function that, when called, invokes func with any additional partial arguments prepended to those provided to the new function.
`$.times`	Call a function n times and also passes the index. If a value is returned in the function then the times method will return an array of those values.

Chaining

$(array: ...)

Method	Usage
`any`	Returns true if callback function returns true for at least one element in the array
`all`	Returns true if callback function returns true for all elements in the array
`each`	Passes each element value to the callback function
`filter`	Filters the arrary to elements for which the callback function returns true
`first`	Returns the first element in the array and terminated the chain
`flatten`	Flattens a nested array of any depth.
`initial`	Gets all but the last element or last n elements of an array.
`map`	Maps each element to the new value returned in the callback function
`slice`	Slices the array based on the start and end position. If an end position is not specified it will slice till the end of the array.
`value`	Returns the array after applying all of the chained operators on it.

Examples

Array

at - `$.at`

Creates an array of elements from the specified indexes, or keys, of the collection. Indexes may be specified as individual arguments or as arrays of indexes.

$.at(["ant", "bat", "cat", "dog", "egg"], indexes: 0, 2, 4) 
=> ["ant", "cat", "egg"]

compact - `$.compact`

Creates an array with all nil values removed.

$.compact([3, nil, 4, 5]) 
=> [3, 4, 5]

$.compact([nil, nil]) as NSObject[] 
=> []

contains - `$.contains`

Checks if a given value is present in the array.

$.contains([1, 2, 3, 1, 2, 3], value: 2) 
=> true

$.contains([1, 2, 3, 1, 2, 3], value: 10) 
=> false

difference - `$.difference`

Creates an array excluding all values of the provided arrays

$.difference([1, 2, 3, 4, 5], [5, 2, 10]) 
=> [1, 3, 4]

every - `$.every`

Checks if the given callback returns true value for all items in the array.

$.every([1, 2, 3, 4], iterator: { $0 < 20 }) 
=> true

$.every([1, 2, 3, 4]) { $0 == 1 } 
=> false

find - `$.find`

Iterates over elements of an array and returning the first element that the callback returns true for.

$.find([1, 2, 3, 4], iterator: { $0 == 2 }) 
=> 2

$.find([1, 2, 3, 4]) { $0 == 10 } 
=> nil

findIndex - `$.findIndex`

This method is like find except that it returns the index of the first element that passes the callback check.

let arr = [["age": 36], ["age": 40], ["age": 1]]
let result = $.findIndex(arr) { $0["age"] < 20 }
result 
=> 2

findLastIndex - `$.findLastIndex`

This method is like findIndex except that it iterates over elements of the array from right to left.

let arr = [["age": 36], ["age": 40], ["age": 1]]
let result = $.findLastIndex(arr) { $0["age"] > 30 }
result
=> 1

first - `$.first(array: AnyObject[])`

Gets the first element in the array.

$.first([1, 2, 3, 4])
=> 1

$.first([]) 
=> nil

flatten - `$.flatten`

Flattens a nested array of any depth.

$.flatten([[3], 4, 5]) as Int[] 
=> [3, 4, 5]

$.flatten([[3], "Hello", 5]) as NSObject[] 
=> [3, "Hello", 5]

$.flatten([[[3], 4], 5]) as Int[] 
=> [3, 4, 5]

frequencies - `$.frequencies`

This method returns a dictionary of values in an array mapping to the total number of occurrences in the array. If passed a function it returns a frequency table of the results of the given function on the arrays elements.

$.frequencies(["a", "a", "b", "c", "a", "b"]) 
=> ["a": 3, "b": 2, "c": 1]

$.frequencies([1, 2, 3, 4, 5]) { $0 % 2 == 0 }
=> [false: 3, true: 2]

indexof - `$.indexof`

Gets the index at which the first occurrence of value is found.

$.indexOf([1, 2, 3, 1, 2, 3], value: 2) 
=> 1

$.indexOf(["A", "B", "C"], value: "B") 
=> 1

$.indexOf([3, 4, 5], value: 5) 
=> 2

$.indexOf([3, 4, 5], value: 3) 
=> 0

$.indexOf([3, 4, 5], value: 2) 
=> nil

initial - `$.initial`

Gets all but the last element or last n elements of an array.

$.initial([3, 4, 5]) 
=> [3, 4]

$.initial([3, 4, 5], numElements: 2) 
=> [3]

intersection - `$.intersection`

Creates an array of unique values present in all provided arrays.

$.intersection([1, 2, 3], [5, 2, 1, 4], [2, 1]) 
=> [1, 2]

last - `$.last`

Gets the last element from the array.

$.last([3, 4, 5]) 
=> 5

lastIndexOf - `$.lastIndexOf`

Gets the index at which the last occurrence of value is found.

$.lastIndexOf([1, 2, 3, 1, 2, 3], value: 2) 
=> 4

rest - `$.rest`

The opposite of initial this method gets all but the first element or first n elements of an array.

$.rest([3, 4, 5]) 
=> [4, 5]

$.rest([3, 4, 5], numElements: 2) 
=> [5]

noop - `$.noop()`

A no-operation function.

$.noop() 
=> nil

min - `$.min`

Retrieves the minimum value in an array.

$.min([2, 1, 2, 3, 4]) 
=> 1

max - `$.max`

Retrieves the maximum value in an array.

$.max([1, 2, 3, 4, 2, 1]) 
=> 4

memoize - `$.memoize`

var times = 0 // to test memoization

let fibMemo = $.memoize { (fib: (Int -> Int), val: Int) -> Int in
    times += 1
    return val == 1 || val == 0 ? 1 : fib(val - 1) + fib(val - 2)
}

let x = fibMemo(5)
times
=> 6

times = 0
let y = fibMemo(5)
times
=> 0

times = 0
let z = fibMemo(6)
times
=> 1

pluck - `$.pluck`

Retrieves the value of a specified property from all elements in the array.

let arr : Dictionary<String, Int>[] = [["age": 20], ["age": 30], ["age": 40]]
$.pluck(arr, value: "age") 
=> [20, 30, 40]

pull - `$.pull`

Removes all provided values from the given array.

$.pull([3, 4, 5, 3, 5], values: 3, 5) 
=> [4]

$.pull([3, 4, 5, 3, 5], values: 4) 
=> [3, 5, 3, 5]

$.pull([3, 4, 5, 3, 5], values: 3, 4, 5) 
=> []

range - `$.range`

Creates an array of numbers (positive and/or negative) progressing from start up to but not including end.

$.range(4) 
=> [0, 1, 2, 3]

$.range(1, endVal: 5) 
=> [1, 2, 3, 4]

$.range(0, endVal: 20, incrementBy: 5) 
=> [0, 5, 10, 15]

sample - `$.sample`

let arr : Int[] = [2, 1, 2, 3, 4]
$.contains(arr, value: $.sample(arr))
=> true

sequence - `$.sequence`

Creates an array of an arbitrary sequence. Especially useful with builtin ranges.

$.sequence(0..4) 
=> [0, 1, 2, 3]

$.sequence(-2.0..2.0) 
=> [-2.0, -1.0, 0.0, 1.0]

$.sequence((0..20).by(5)) 
=> [0, 5, 10, 15]

$.sequence("abc") 
=> ["a", "b", "c"]

remove - `$.remove`

Removes all elements from an array that the callback returns true.

let result = $.remove([1, 2, 3, 4, 5, 6]) { $0 == 2 || $0 == 3 }
result
=> [1, 4, 5, 6]

sortedIndex - `$.sortedIndex`

Gives the smallest index at which a value should be inserted into a given the array is sorted.

$.sortedIndex([3, 4, 6, 10], value: 5)
=> 2

$.sortedIndex([10, 20, 30, 50], value: 40)
=> 3

union - `$.union`

Creates an array of unique values, in order, of the provided arrays.

$.union([1, 2, 3], [5, 2, 1, 4], [2, 1]) 
=> [1, 2, 3, 4, 5]

merge - `$.merge`

Creates an array of all values, including duplicates, of the arrays in the order they are provided.

let arr  = [1, 5]
let arr2 = [2, 4]
let arr3 = [5, 6]
let result = $.merge(arrays: arr, arr2, arr3)
result
=> [1, 5, 2, 4, 5, 6]

uniq - `$.uniq`

Creates a duplicate-value-free version of an array.

$.uniq([1, 2, 1, 3, 1])
=> [1, 2, 3]

without - `$.without`

Creates an array excluding all provided values.

$.without([3, 4, 5, 3, 5], values: 3, 5)
=> [4]

$.without([3, 4, 5, 3, 5], values: 4)
=> [3, 5, 3, 5]

$.without([3, 4, 5, 3, 5], values: 3, 4, 5)
=> []

xor - `$.xor`

Creates an array that is the symmetric difference of the provided arrays.

$.xor([1, 2, 3], [5, 2, 1, 4])
=> [3, 4, 5]

zip - `$.zip`

Creates an array of grouped elements, the first of which contains the first elements of the given arrays.

$.zip(["fred", "barney"], [30, 40], [true, false]) as NSObject[] 
=> [["fred", 30, true], ["barney", 40, false]]

zipObject - `$.zipObject`

Creates an object composed from arrays of keys and values.

$.zipObject(["fred", "barney"], values: [30, 40]) as Dictionary<String, Int> 
=> ["fred": 30, "barney": 40]

partition - `$.partition`

Produces an array of arrays, each containing n elements, each offset by step. Stops after a partition is less than n length.

let arr = [1, 2, 3, 4, 5]
$.partition(arr, n: 2)
=> [[1, 2], [3, 4]]

$.partition(arr, n: 4, step: 1)
=> [[1, 2, 3, 4], [2, 3, 4, 5]]

$.partition(arr, n: 4, step: 1, pad: nil)
=> [[1, 2, 3, 4], [2, 3, 4, 5], [3, 4, 5]]

$.partition(arr, n: 4, step: 1, pad: [6, 7, 8])
=> [[1, 2, 3, 4], [2, 3, 4, 5], [3, 4, 5, 6]]

partitionAll - `$.partitionAll`

Produces an array of arrays, each containing n elements, each offset by step. Continues after a partition is less than n length.

$.partitionAll([1, 2, 3, 4, 5], n:4, step: 1)
=> [[1, 2, 3, 4], [2, 3, 4, 5], [3, 4, 5], [4, 5], [5]]

partitionBy - `$.partitionBy`

Applies a function to each element in array, splitting it each time the function returns a new value.

$.partitionBy([1, 2, 3, 4, 5]) { $0 % 2 == 0 }
=> [[1], [2, 4], [3, 5], [6]]

$.partitionBy([1, 7, 3, 6, 10, 12]) { $0 % 3 }
=> [[1, 7], [3, 6], [10], [12]]

Dictionary

keys - `$.keys`

Creates an array of keys given a dictionary.

$.keys(["Dog": 1, "Cat": 2])
=> ["Dog", "Cat"]

values - `$.values`

Creates an array of values given a dictionary

$.values(["Dog": 1, "Cat": 2])
=> [1, 2]

merge - `$.merge`

Merges all of the dictionaries together and the latter dictionary overrides the value at a given key

let dict: Dictionary<String, Int> = ["Dog": 1, "Cat": 2]
let dict2: Dictionary<String, Int> = ["Cow": 3]
let dict3: Dictionary<String, Int> = ["Sheep": 4]
$.merge(dict, dictionaries: dict2, dict3)

pick - `$.pick`

Creates a shallow clone of a dictionary composed of the specified keys.

$.pick(["Dog": 1, "Cat": 2, "Cow": 3], keys: "Dog", "Cow")

omit - `$.omit`

Creates a shallow clone of a dictionary excluding the specified keys.

$.omit(["Dog": 1, "Cat": 2, "Cow": 3], keys: "Cat", "Dog")

Object

tap - `$.tap`

Invokes interceptor with the object and then returns object.

var beatle = Car(name: "Fusca")
$.tap(beatle, {$0.name = "Beatle"}).color = "Blue"

Function

after - `$.after`

Creates a function that executes passed function only after being called n times.

var saves = ["profile", "settings"];
let asyncSave = { (function: () -> ()?) in
   function() // Saving right away for testing but in real world would be async
}
var isDone = false
var completeCallback = $.after(saves.count) {
   isDone = true
}
for elem in saves {
   asyncSave(completeCallback)
}
isDone 
=> true

bind - `$.bind`

Creates a function that, when called, invokes func with the binding of arguments provided.

let helloWorldFunc = $.bind({(T...) in T[0] + " " + T[1] + " from " + T[2] }, "Hello", "World", "Swift")
helloWorldFunc() 
=> "Hello World from Swift"

id - `$.id`

The identify function which simply returns the argument its given.

$.id("Hello World from Swift")
=> "Hello World from Swift"

partial - `$.partial`

Creates a function that, when called, invokes func with any additional partial arguments prepended to those provided to the new function.

let partialFunc = $.partial({(T...) in T[0] + " " + T[1] + " from " + T[2] }, "Hello")
partialFunc("World", "Swift") 
=> "Hello World from Swift"

times - `$.times`

Call a function n times and also passes the index. If a value is returned in the function then the times method will return an array of those values.

let fun = $.bind({ (names: String...) -> String in
   let people = $.join(names, separator: " from ")
   return "Hello \(people)"
   }, "Ankur", "Swift")
$.times(2, function: fun) as String[] 
=> ["Hello Ankur from Swift", "Hello Ankur from Swift"]

Chaining - `$(array: ...)`

$(array: [1, 2, 3])

$(array: [1, 2, 3]).first() as Int 
=> 1

$(array: [[1, 2], 3, [[4], 5]]).flatten().initial(2).value() as Int[] 
=> [1, 2, 3]

$(array: [[1, 2], 3, [[4], 5]]).initial().flatten().first() as Int 
=> 1

var chain = $(array: [10, 20, 30, 40, 50])
var elements: Int[] = []
chain.each { elements += $0 as Int }
elements as Int[] 
=> [10, 20, 30, 40, 50]

var chain = $(array: [10, 20, 30, 40, 50])
chain.all { ($0 as Int) < 100 } 
=> true

chain.all { ($0 as Int) < 40 } 
=> false

chain.any { ($0 as Int) < 40 } 
=> true

Contributing

If you are interested in contributing

Please fork this project
Implement new methods or changes in the Dollar.swift file in the Classes folder
Write tests in DollarTests.swift file in the DollarTests folder
Submit a pull request.

Roadmap

More functions such as curry function and then ability to lazily evaluat chained expressions.

Why not extend collection?

The project doesnt extend or monkey patch the collection using the extension features to keep it purely functional and
To not override any methods via extensions if Apple decides to add those methods into the collection class themselves as part of the language update. This could lead to inconsistent behavior for those who use the library and those who don't.

Files

README.md

Latest commit

History

README.md

File metadata and controls

Dollar.$wift

Contents

Setup

Usage

Array Methods

Dictionary Methods

Object Methods

Function Methods

Chaining

Examples

Array

at - $.at

compact - $.compact

contains - $.contains

difference - $.difference

every - $.every

find - $.find

findIndex - $.findIndex

findLastIndex - $.findLastIndex

first - $.first(array: AnyObject[])

flatten - $.flatten

frequencies - $.frequencies

indexof - $.indexof

initial - $.initial

intersection - $.intersection

last - $.last

lastIndexOf - $.lastIndexOf

rest - $.rest

noop - $.noop()

min - $.min

max - $.max

memoize - $.memoize

pluck - $.pluck

pull - $.pull

range - $.range

sample - $.sample

sequence - $.sequence

remove - $.remove

sortedIndex - $.sortedIndex

union - $.union

merge - $.merge

uniq - $.uniq

without - $.without

xor - $.xor

zip - $.zip

zipObject - $.zipObject

partition - $.partition

partitionAll - $.partitionAll

partitionBy - $.partitionBy

Dictionary

keys - $.keys

values - $.values

merge - $.merge

pick - $.pick

omit - $.omit

Object

tap - $.tap

Function

after - $.after

bind - $.bind

id - $.id

partial - $.partial

times - $.times

Chaining - $(array: ...)

Contributing

Roadmap

Why not extend collection?

at - `$.at`

compact - `$.compact`

contains - `$.contains`

difference - `$.difference`

every - `$.every`

find - `$.find`

findIndex - `$.findIndex`

findLastIndex - `$.findLastIndex`

first - `$.first(array: AnyObject[])`

flatten - `$.flatten`

frequencies - `$.frequencies`

indexof - `$.indexof`

initial - `$.initial`

intersection - `$.intersection`

last - `$.last`

lastIndexOf - `$.lastIndexOf`

rest - `$.rest`

noop - `$.noop()`

min - `$.min`

max - `$.max`

memoize - `$.memoize`

pluck - `$.pluck`

pull - `$.pull`

range - `$.range`

sample - `$.sample`

sequence - `$.sequence`

remove - `$.remove`

sortedIndex - `$.sortedIndex`

union - `$.union`

merge - `$.merge`

uniq - `$.uniq`

without - `$.without`

xor - `$.xor`

zip - `$.zip`

zipObject - `$.zipObject`

partition - `$.partition`

partitionAll - `$.partitionAll`

partitionBy - `$.partitionBy`

keys - `$.keys`

values - `$.values`

merge - `$.merge`

pick - `$.pick`

omit - `$.omit`

tap - `$.tap`

after - `$.after`

bind - `$.bind`

id - `$.id`

partial - `$.partial`

times - `$.times`

Chaining - `$(array: ...)`