LambdaDriver

虚弦斥力場生成システム

LambdaDriver drives your code more functional.

# [:foo, :bar, :baz].map{|s| s.to_s }.map{|s| s.upcase }
# [:foo, :bar, :baz].map(&:to_s).map(&:upcase)

[:foo, :bar, :baz].map(&:to_s >> :upcase ) # => ["FOO",  "BAR",  "BAZ"]

# [:foo, :hoge, :bar, :fuga].select{|s| s.to_s.length > 3} # => [:hoge, :fuga]

[:foo, :hoge, :bar, :fuga].select(&:to_s >> :length >> 3._(:<)) # => [:hoge, :fuga]

Build status

Installation

Add this line to your application's Gemfile:

gem 'lambda_driver'

And then execute:

$ bundle

Or install it yourself as:

$ gem install lambda_driver

Usage

Proc/lambda/Symbol/Method extensions

call
compose
with_args
flip
curry

alias :< to Proc#call

  f = lambda{|x| x.to_s }
  f < :foo # => "foo"

alias :+@ to Proc#to_proc

  +:to_s           # => #<Proc:0x007ff78aadaa78>
  +:to_s < :foo    # => "foo"

Proc#compose

Returns new lambda which composed self and given function. A composed proc called with args, executes `self.(g(*args)).

  f = lambda{|x| x.to_s * 2 }
  g = lambda{|y| y.length }

  h = f.compose g  # => #<Proc:0x007ff78aa2ab2>
  h.(:hoge)        # => "44" ( == f.call(g.call(:hoge)) )

This method is aliased as <<.

  f << g          # => f.compose(g)
  f << g < :hoge  # => "44" ( == f.call(g.call(:hoge)) )

Proc#with_args

Returns partially applied function that has 2nd and more parameters are fixed by given *args.

  f = lambda{|x, y, z| [x, y, z]}

  h = f.with_args(:a, :b)   # => #<Proc:0x007ff78a9c5ca0>
  h.(:c)                    # => [:c, :a, :b] ( == f.call(:c, :a, :b) )

This method is aliased as *.

  f = lambda{|x, y| [x, y]}

  f * :foo          # => #<Proc:0x007ff78a987540> (== f.with_args(:foo) )
  f * :foo < :bar   # => [:bar,  :foo] ( == f.with_args(:foo).call(:bar) )

Proc#flip

Returns function whose parameter order swaped 1st for 2nd. A result of filped fuction is curried by Proc#curry.

  f = lambda{|x, y, z| [x, y, z]}

  h = f.flip                    # => #<Proc:0x007ff78a942fa>
  h.call(:a).call(:b).call(:c)  # => [:b, :a, :c] (== f.curry.call(:b).call(:a).call(:b))
  h < :a < :b < :c              # => [:b, :a, :c] (== f.curry.call(:b).call(:a).call(:b))

If arguments is var-args, pass explicitly arity to curring.

  p = Proc.new{|*args| args.inspect }

  p.arity                           # => -1
  p.flip(3).call(:a).(:b).(:c)      # => "[:b, :a, :c]"
  p.flip(4).call(:a).(:b).(:c).(:d) # => "[:b, :a, :c, :d]"

If arity is 0 or 1, flip returns itself.

This method is aliased as ~@.

  ~f # =>             #<Proc:0x007ff78a8e22c> (== f.filp)
  ~f < :a < :b < :c   # => [:b, :a, :c] (== f.filp.call(:b).call(:a).call(:b))

Symbol extensions

to_method

Symbol#to_method

Symbol#to_method generates a function that extract Method object from given arguments. This method is aliased as -@.

  (-:index).call("foobarbaz")             # => #<Method: String#index>
  (-:index).call("foobarbaz").call("bar") # => 3 (== "foobarbaz".index(3) )

  -:index < "foobarbaz"         # => #<Method: String#index>
  -:index < "foobarbaz" < "bar" # => 3 (== "foobarbaz".index(3) )

Class extensions

alias instance_method, :/

  String / :index # => #<UnboundMethod: String#index>

UnboundMethod extensions

alias bind, :<

  String / :index                    # => #<UnboundMethod: String#index>
  String / :index < "foobarbaz"      # => #<Method: String#index>
  String / :index < "foobarbaz" < 3  # => 3 (== "foobarbaz".index(3) )

Combinators

ski combinator

Object extensions

obj.ap(|>)
obj._
obj.disjunction(f)

Object#revapply

Object#revapply is applies self to given proc/block.

  f = lambda{|x| x * 2 }

  "foo".revapply(f) #  => "fooffoo" (== f.call("foo") )

Object#_

Object#_ is shortcut to quickly extract Method object.

"foobarbaz"._.index         # => #<Method: String#index>
"foobarbaz"._.index < "bar" # => 3 (== "foobarbaz".index(3) )

2._(:>=)                    # => #<Method: Fixnum#>=>
[1, 2, 3].select(&2._(:>=)) # => [1, 2]( = [1, 2].select{|n| 2 >= n})

Object#disjunction

Object#disjunction select self or result of applied self to given function. if f(self) is nil, returns self, otherwise return f(self).

  f = lambda{|x| x % 2 == 0 ? nil : x * 2}

  2.disjunction(f) # => 2 (disjunction returns reciever object)
  3.disjunction(f) # => 6 (disjunction returns f(3) )

Contributing

Fork it
Create your feature branch (git checkout -b my-new-feature)
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create new Pull Request

epictetus / lambda_driver Goto Github PK

lambda_driver's Introduction