[Haskell-cafe] Polymorphic variants
jon at ffconsultancy.com
Wed Jul 25 18:04:16 EDT 2007
Does Haskell have anything similar to OCaml's polymorphic variants?
They act as inferred sum types:
# let rec eval = function
| `Int n -> n
| `Add(f, g) -> eval f + eval g
| `Mul(f, g) -> eval f * eval g;;
val eval :
([< `Add of 'a * 'a | `Int of int | `Mul of 'a * 'a ] as 'a) -> int = <fun>
Dr Jon D Harrop, Flying Frog Consultancy Ltd.
OCaml for Scientists
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