Created
October 7, 2013 19:22
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Comparison of the straightforward embedding of a basic tenet of category theory in Scala vs Haskell.
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yonedaLemma = Iso (flip fmap) ($ id) |
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def yonedaLemma[F[_]:Functor, A]: F[A] <=> (({type λ[α] = A => α })#λ ~> F) = | |
new (F[A] <=> (({type λ[α] = A => α })#λ ~> F)) { | |
def to(fa: F[A]) = new (({type λ[α] = A => α })#λ ~> F) { | |
def apply[R](f: A => R) = Functor[F].map(fa)(f) | |
} | |
def from(f: (({type λ[α] = A => α })#λ ~> F)) = f(a => a) | |
} |
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How is the affected by recent scala, typelevel scala, or dotty features?