[Haskell-cafe] Re: [Haskell] How to define tail function for
Even/Odd GADT lists?
daveroundy at gmail.com
Wed Apr 23 19:46:49 EDT 2008
2008/4/23 Martijn Schrage <martijn at cs.uu.nl>:
> It depends a bit on what you want to use these lists for, but the following
> encoding works for your examples and doesn't need the type class.
> data E
> data O
> type Even = (E,O)
> type Odd = (O,E)
That's a nice little trick! I like how you achieve type signatures
relating two distinct types just by sticking them in a tuple. :)
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