15 Sep
2014
15 Sep
'14
12:58 p.m.
* Richard Eisenberg
Have you tried using closed type families with the type-level (==) operator from GHC 7.8's Data.Type.Equality? That's how I've done unions before. The key step is to use a closed type family to write a type family equation that triggers when two types do *not* equal.
Let me know if you need more info... Thanks. I will take a look for my education, but I am on Debian, so no more, then ghc 7.6.3.
I found type-settheory package, but it fails to build.
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Best regards, Dmitry Bogatov