GHCJS - Haskell in the Browser

Re:GHCJS - Haskell in the Browser by tel on Wednesday June 26, 2013 @04:21PM (#5948744)

You could do it like in Agda,

    data ApplicativeI f = 
      AI { pure      :: forall a. a -> f a
         , ap        :: forall a b. f (a -> b) -> f a -> f b
         , _FunctorI :: FunctorI f }

    data MonadI m = 
      AI { bind          :: forall a b. (a -> m b) -> m a -> m b
         , _ApplicativeI :: ApplicativeI m }

    return :: _MonadI m -> a -> m a
    return (MonadI { _ApplicativeI = ApplicativeI { pure = fn } }) = fn

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Re:GHCJS - Haskell in the Browser by colanderman on Wednesday June 26, 2013 @07:29PM (#5949794)

Almost, but that's not extensible: I can't declare some new typeclass Foo and then declare that every x s.t. Monad x is also Foo x without editing the definition of Monad.

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Re:GHCJS - Haskell in the Browser by tome on Thursday June 27, 2013 @03:29AM (#5951087)

Instead of providing an instance declaration you provide a value of MonadI f -> FooI f.

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Re:GHCJS - Haskell in the Browser by tel on Thursday June 27, 2013 @03:01PM (#5954077)

Exactly, and then that function is "proof" of the relationship.

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