[Haskell-cafe] What's this pattern called?
anotheraddress at gmx.de
Thu Oct 22 07:29:31 EDT 2009
On Thursday 22 October 2009 09:47:32 Martijn van Steenbergen wrote:
> Bonjour café,
> > data ExprF r
> > = Add r r
> > | Sub r r
> > | Mul r r
> > | Div r r
> > | Num Int
> This is a well-known pattern that for example allows nice notation of
> morphisms. But what is it called?
The multirec package calls this the "pattern functor" (more accurately, it
generates a sum-of-products-like higher order functor whose fixed point is
isomorphic to your family of types, and calls that the pattern functor).
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