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When unifying constructor-level unification variables, also unify their kinds
author Adam Chlipala <adam@chlipala.net>
date Fri, 01 Aug 2014 16:11:36 -0400
parents 71bafe66dbe1
children
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datatype sum a b = Left of a | Right of b

val l : sum int string = Left 5
val r : sum int string = Right "Hi"

val show = fn x : sum int string => case x of Left _ => "Left _" | Right s => s

val page = fn x => <html><body>
        {cdata (show x)}
</body></html>

val main : unit -> page = fn () => <html><body>
        <li><a link={page l}>Left</a></li>
        <li><a link={page r}>Right</a></li>
</body></html>