view tests/case.ur @ 1623:218e2a9a53d0

Better error messages about non-SQL-izability of types
author Adam Chlipala <adam@chlipala.net>
date Sat, 03 Dec 2011 15:59:21 -0500
parents 71bafe66dbe1
children
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datatype t = A | B

val swap = fn x : t => case x of A => B | B => A

datatype u = C of t | D

val out = fn x : u => case x of C y => y | D => A

datatype nat = O | S of nat

val is_two = fn x : nat =>
        case x of S (S O) => A | _ => B

val zero_is_two = is_two O
val one_is_two = is_two (S O)
val two_is_two = is_two (S (S O))