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functional-programmingmonadscontinuations

Are continuations monads?

Can continuations be said to be monads? Are they a subset of monads or are they simply a way of implementing monads?

Edit: Or maybe I got it wrong and monads is a more abstract concept than continuations? (So I'm really comparing apples to oranges here)

Solution

  • Briefly, since the 'bind' of a monad takes an effective continuation (a lambda of the 'rest of the computation') as an argument, monads are continuations in that sense. On the flip side, continuation-passing style can be effectively implemented in a non-CPS language using monadic syntax sugars, as suggested by a number of misc links below.

    From the 'all about monads' tutorial in Haskell:

    https://www.haskell.org/haskellwiki/All_About_Monads#The_Continuation_monad

    An F# continuation monad, used to implement 'break' and 'continue' for for-style-loops

    http://cs.hubfs.net/forums/thread/9311.aspx

    And example of applying a continuation monad to a problem in F#:

    http://lorgonblog.spaces.live.com/blog/cns!701679AD17B6D310!256.entry