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derrickturk/poly.ml

Created March 11, 2021 22:00
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working around the lack of rank-2 types in OCaml
Raw
poly.ml
type poly_fn = { f : 'a. 'a -> 'a }
let ap_poly : poly_fn -> int -> bool -> int * bool = fun pf x y ->
(pf.f x, pf.f y)
let ap_poly_obj (obj: <f: 'a. 'a -> 'a>) x y = (obj#f x, obj#f y)
let id x = x
let (x, y) = ap_poly { f = id } 3 true
let (x2, y2) = ap_poly_obj (object method f : 'a. 'a -> 'a = id end) 3 true
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