31 Jul
2014
31 Jul
'14
7 a.m.
Konstantine Rybnikov
Excuse me if the question is silly.
Thought this MonadCatchIO will be removed in next version of snap, current version has it and I can't understand this derivation: [0]
L.Lensed seems like just a newtype wrapper around a function [1], and there is no instance of MonadCatchIO for a function.
How is it derived?
You probably just missed it, but there's a MonadCatchIO instance for L.Lensed, and so the derived instance for Handler is trivial.