Named parameters (keyword arguments) for Haskell

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Stackage Nightly 2024-06-21:
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BSD-3-Clause licensed by Vladislav Zavialov
Maintained by Vladislav Zavialov
This version can be pinned in stack with:named-,2043

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named is a lightweight library for named function parameters (keyword arguments) based on overloaded labels. Keyword arguments have several advantages over positional arguments:

  • they can be supplied in arbitrary order

  • their names serve as documentation at call site

  • it is impossible to accidentally mix them up

Unlike newtype wrappers, keyword arguments don't pollute the global namespace, don't require top-level definitions, and don't need to be exported.

This implementation of named parameters is typesafe, provides good type inference, descriptive type errors, and has no runtime overhead.

Example usage:

import Named

createSymLink :: FilePath `Named` "from" -> FilePath `Named` "to" -> IO ()
createSymLink (Named from) (Named to) = ...

main = createSymLink ! #from "/path/to/source"
                     ! #to "/target/path"


  • First version. Released on an unsuspecting world.