BSD-3-Clause licensed by Oleg Grenrus, Ryan Scott, Erik Hesselink, Martijn van Steenbergen
This version can be pinned in stack with:type-equality-1@sha256:7cd952c3ebf0da36ee05544e6209a850b22205fa8b749e17f4bacc5a8fe15269,1611

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Used by 1 package in nightly-2023-02-04(full list with versions):

This library defines a propositional equality data type, shims Data.Type.Equality as well as possible for older GHCs (< 7.8).

data a :~: b where
    Refl :: a :~: a

The module Data.Type.Equality.Hetero shims :~~: equality, for compilers with PolyKinds



  • Rewrite the library to contain a shim of recent base Data.Type.Equality module.


  • Add subst2. Thanks to James Koppel.


  • Turn on PolyKinds for GHC >= 7.6. Thanks to Ben Franksen.

  • Move ‘Build-depends’ to ‘Library’ section. Thanks to Brent Yorgey.

  • Added EqT instance for (:=:)
  • Removed ‘cast’ as synonym for ‘coerce’.
  • Show and read instances for (:=:).
  • Lots of small changes.


  • Initial version.