State Monad in Co{co,ffeeScript}

state-monad.co

push = (value) -> (stack) -> {value, stack: [value]concat stack}

pop = (stack) -> value: stack.0, stack: stack.slice 1

bind = (stackOperation, continuation) -> (stack) ->
  result = stackOperation stack
  continuation(result.value) result.stack

result = (value) -> (stack) -> {value, stack}

computation1 = do
  \ <- bind push 4
  \ <- bind push 5
  a <- bind pop
  b <- bind pop
  result a + ":" + b

computation2 = do
  \ <- bind push 2
  \ <- bind push 3
  a <- bind pop
  b <- bind pop
  result a + ":" + b

composed = do
  a <- bind computation1
  b <- bind computation2
  result a + " " + b

console.log composed([])value

state-monad.coffee

push = (value) -> (stack) -> {value, stack: [value].concat stack}

pop = (stack) -> value: stack[0], stack: stack.slice 1

bind = (stackOperation, continuation) -> (stack) ->
  result = stackOperation stack
  continuation(result.value) result.stack

result = (value) -> (stack) -> {value, stack}

computation1 = bind \
  push(4), -> bind \
  push(5), -> bind \
  pop, (a) -> bind \
  pop, (b) ->
    result a + ":" + b

computation2 = bind \
  push(2), -> bind \
  push(3), -> bind \
  pop, (a) -> bind \
  pop, (b) ->
    result a + ":" + b

composed = bind \
  computation1, (a) -> bind \
  computation2, (b) ->
    result a + " " + b

console.log composed([]).value