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| author | Matthew Pickering <matthewtpickering@gmail.com> | 2022-03-02 17:28:08 +0000 |
|---|---|---|
| committer | Matthew Pickering <matthewtpickering@gmail.com> | 2022-03-03 09:55:12 +0000 |
| commit | 12487340c1a37fb90003f54fd910ef762fa4b17d (patch) | |
| tree | 1c7a67469387ea8a294afcde003c877d3c09fdb8 | |
| parent | aeea6bd588060108dea88996c19f48b9e50adad2 (diff) | |
| download | haskell-wip/coerce-docs.tar.gz | |
docs: Add note to unsafeCoerce function that you might want to use coerce [skip ci]wip/coerce-docs
Fixes #15429
| -rw-r--r-- | libraries/base/Unsafe/Coerce.hs | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/libraries/base/Unsafe/Coerce.hs b/libraries/base/Unsafe/Coerce.hs index 930514ce81..ec5b793f87 100644 --- a/libraries/base/Unsafe/Coerce.hs +++ b/libraries/base/Unsafe/Coerce.hs @@ -267,6 +267,10 @@ unsafeEqualityProof = case unsafeEqualityProof @a @b of UnsafeRefl -> UnsafeRefl -- (which have different kinds!) because it's really just a newtype. -- Note: there is /no guarantee, at all/ that this behavior will be supported -- into perpetuity. +-- +-- +-- For safe zero-cost coercions you can instead use the 'Data.Coerce.coerce' function from +-- "Data.Coerce". unsafeCoerce :: forall (a :: Type) (b :: Type) . a -> b unsafeCoerce x = case unsafeEqualityProof @a @b of UnsafeRefl -> x |