32 lines
547 B
Plaintext
32 lines
547 B
Plaintext
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module Main where
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import Prelude
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import Effect (Effect)
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import Effect.Console (log)
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main :: Effect Unit
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main = log "hello world"
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---------- Existentials
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type ShowConstraint a = Show a => a
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type Exists :: forall k. (k -> Type) -> Type
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type Exists c = forall r. (forall a. c a -> r) -> r
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type Showable = Exists ShowConstraint
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mkShowable :: forall a. Show a => a -> Showable
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mkShowable inner continue = continue inner
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demo1 :: Showable
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demo1 = mkShowable 1
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demo2:: Showable
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demo2 = mkShowable "a"
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demo3:: Showable
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demo3 = mkShowable true
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