Module: Fr::State

Extended by:
Monad
Defined in:
lib/fr/monad/state.rb

Class Method Summary collapse

Methods included from Monad

applyM, composeM, filterM, foldM, forM, join, liftM, mapM, sequence, unlessM, whenM, zipM

Methods included from Functor

#void

Class Method Details

.bind(f, &g) ⇒ Object 



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# File 'lib/fr/monad/state.rb', line 33

def bind(f, &g)
  lambda do |state|
    tuple = f.call(state)
    g.call(tuple[:value]).call(tuple[:state])
  end
end

.eval(computation, state) ⇒ Object 



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# File 'lib/fr/monad/state.rb', line 16

def eval(computation, state)
  computation.call(state)[:value]
end

.exec(computation, state) ⇒ Object 



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# File 'lib/fr/monad/state.rb', line 20

def exec(computation, state)
  computation.call(state)[:state]
end

.get ⇒ Object 



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# File 'lib/fr/monad/state.rb', line 49

def get
  lambda do |state|
    Hash[state: state, value: state]
  end
end

.put(n) ⇒ Object

Actions



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# File 'lib/fr/monad/state.rb', line 43

def put(n)
  lambda do |state|
    Hash[state: n, value: nil]
  end
end

.run(computation, state) ⇒ Object

Evaluators



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# File 'lib/fr/monad/state.rb', line 12

def run(computation, state)
  computation.call(state)
end

.unit(value) ⇒ Object

Combinators



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# File 'lib/fr/monad/state.rb', line 27

def unit(value)
  lambda do |state|
    Hash[state: state, value: value]
  end
end

.update ⇒ Object 



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# File 'lib/fr/monad/state.rb', line 55

def update
  lambda do |state|
    Hash[state: yield(state), value: nil]
  end
end