Re: [Haskell-cafe] -XGADTs changes type for program that does not contain GADT

"Implies" is too strong, isn't it? My understanding is -XGADTs turns on -XMonoLocalBinds by default, but you can use -XGADTs with -XNoMonoLocalBinds Tom

El 12 feb 2016, a las 08:05, Andres Löh escribió:

Hi.

...

the following type-correct program does not contain GADT syntax. When I activate GADT language pragma, it does no longer typecheck.

This is because -XGADTs implies -XMonoLocalBinds. See https://ghc.haskell.org/trac/ghc/blog/LetGeneralisationInGhc7 for a longer explanation.

Cheers, Andres

-- Andres Löh, Haskell Consultant Well-Typed LLP, http://www.well-typed.com

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