Add message for GHC-72771 "Mismatched default method signature" #524
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Bodigrim
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Feb 2, 2025
| introduced: 9.8.1 | ||
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| This error means that there is a type class with some method `m` for which a [default signature](https://ghc.gitlab.haskell.org/ghc/doc/users_guide/exts/default_signatures.html) was defined, but that default signature does not match the type signature of `m`. |
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Let's link a stable released documentation instead of GitLab:
Suggested change
| This error means that there is a type class with some method `m` for which a [default signature](https://ghc.gitlab.haskell.org/ghc/doc/users_guide/exts/default_signatures.html) was defined, but that default signature does not match the type signature of `m`. | |
| This error means that there is a type class with some method `m` for which a [default signature](https://downloads.haskell.org/ghc/9.12.1/docs/users_guide/exts/default_signatures.html) was defined, but that default signature does not match the type signature of `m`. |
Bodigrim
reviewed
Feb 2, 2025
| class Enum a where | ||
| enum :: [a] | ||
| default enum :: (Int ~ a) => a | ||
| enum = [1..] |
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-
If you rename it to
module Lib wherethere would be no need to definemain :: IO (), minimizing the example. -
Let's add
{-# LANGUAGE TypeOperators #-}, otherwise recent GHCs throw a warning about~. -
Could we please rename
Enum -> Enumerate,enum -> enumerate? So that we do not clash with a usualclass EnumfromPrelude.
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Thank you, that all sounds much better!
I made changes accordingly.
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Bodigrim
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Thanks! |
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