Proposal: Use (.) and id from Control.Category in Prelude

Johan Tibell johan.tibell at
Sat Jun 14 20:31:15 UTC 2014

On Sat, Jun 14, 2014 at 10:15 PM, Carter Charbonneau <zcarterc at>

> (.) and id are generalized in the Category class in Control.Category. In
> the past, many libraries have instructed users to use (.) and id from
> Control.Category for composition of their types. Importing these types into
> Prelude shouldn't break existing code, and makes libraries that use
> Category easier to use.
> Discussion period: 4 weeks


This would benefit very few Haskell users and make error messages terrible.
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