HEADS UP: Applicative-Monad incoming

Austin Seipp austin at well-typed.com
Mon Aug 4 11:01:38 UTC 2014

Hi all,

The Applicative Monad changes will be landing in HEAD soon, hopefully
within a few hours once ./validate finishes and I triple-check

Why am I sending this? To warn you that you need to update Happy to
*at least* version 1.19.4 before you can build GHC again. This is
because Happy emitted parsers that had instances of Monad, and thus
Happy needed to be fixed to also emit Applicative instances.

Please be sure to upgrade your workstations, buildbots, toasters, etc
so you don't get caught by surprise. ./configure will fail you if your
Happy is invalid.

This message is brought to you by sleep deprivation and almost two
days of hunting an infinite loop in my changeset, which was quite
annoying to track down. I'm sure something will still go wrong during


Austin Seipp, Haskell Consultant
Well-Typed LLP, http://www.well-typed.com/

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