2015-10-01 13:23 GMT+02:00 Matthew Pickering <matthewtpicker...@gmail.com>:
> I think that the current state of pattern synonym signatures is quite > confusing, especially regarding the constraints. [...] Thanks to an off-list email from Matthew (thanks for that!) I found out that pattern FOO = 1234 :: Int behaves differently from pattern FOO :: Int pattern FOO = 1234 In the former case one has to use ScopedTypeVariables, in the latter case it works without it. This is not really intuitive, although I'll have to admit that I've had only a cursory look at the "Typing of pattern synonyms" section in the GHC manual. But even after re-reading it, it's not really clear where the difference in the above example comes from. So in a nutshell: +1 for the "quite confusing" argument. Cheers, S.
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