Re: [Haskell-cafe] Type union

i should point out the HList package has a lot of tooling for things like this, and the author Adam says that its quite usable (aside from the dearth of docs beyond the crazy typeful haddocks :) ) https://hackage.haskell.org/package/HList On Mon, Sep 15, 2014 at 12:58 PM, Dmitry Bogatov wrote:

* Richard Eisenberg [2014-09-15 08:56:05-0400]

...

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.

-- Best regards, Dmitry Bogatov , Free Software supporter, esperantisto and netiquette guardian. GPG: 54B7F00D

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