[Haskell-cafe] The rmonad package is mysterious

Simon Marechal simon at banquise.net
Wed Apr 10 20:30:55 CEST 2013

I tried to do something simple using the rmonad package (attached).

I followed the example that's in haddocks (it is wrong, constraints has
no arguments), grabbed the list of extensions from rmonad's source, but
this program doesn't typecheck:

Could not deduce (Hashable a) arising from a use of `HM.singleton'

This seems to be an obvious use of this package ... am I missing something ?
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