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view record.ur @ 27:ca1c07d49b5e
Type-directed case matching for variants.
author | Edward Z. Yang <ezyang@mit.edu> |
---|---|
date | Thu, 26 Jul 2012 16:39:02 -0400 |
parents | 6cd839818393 |
children | f55f66c6fdee |
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fun numFields [r ::: {Type}] (fl : folder r) (r : $r) : int = @fold [fn _ => int] (fn [nm ::_] [u ::_] [r ::_] [[nm] ~ r] acc => acc+1) 0 fl fun mem [a ::: Type] [ns ::: {Unit}] (_ : eq a) (fl : folder ns) (x : a) (r : $(mapU a ns)) : bool = @foldUR [a] [fn _ => bool] (fn [nm ::_] [r ::_] [[nm] ~ r] y acc => acc || x = y) False fl r fun equal [ts ::: {Type}] (eqs : $(map eq ts)) (fl : folder ts) (r1 : $ts) (r2 : $ts) : bool = @foldR3 [eq] [ident] [ident] [fn _ => bool] (fn [nm ::_] [t ::_] [r ::_] [[nm] ~ r] isEq x y acc => acc && @eq isEq x y) True fl eqs r1 r2