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Diffstat (limited to 'libraries/ghc-prim/changelog.md')
| -rw-r--r-- | libraries/ghc-prim/changelog.md | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/libraries/ghc-prim/changelog.md b/libraries/ghc-prim/changelog.md index 94ede15904..41a8f5f864 100644 --- a/libraries/ghc-prim/changelog.md +++ b/libraries/ghc-prim/changelog.md @@ -1,6 +1,19 @@ ## next (edit as necessary) - `magicDict` is now defined in `GHC.Magic.Dict` instead of `GHC.Prim`. + It now has the type: + + magicDict :: forall {rr :: RuntimeRep} dt st (r :: TYPE rr). (dt => r) -> st -> r + + `magicDict` can now be used without defining an intermediate data type. For example, + the `withTypeable` function from `base`'s `Data.Typeable` module can now be defined as: + + withTypeable :: forall k (a :: k) rep (r :: TYPE rep). () + => TypeRep a -> (Typeable a => r) -> r + withTypeable rep k = magicDict @(Typeable a) k rep + + Note that the explicit type application is required, as the call to + `magicDict` would be ambiguous otherwise. ## 0.8.0 (edit as necessary) |