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Fix broken conversions into naturals

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Taylor Fausak 2021-05-28 18:57:15 +00:00
parent 566ff323fd
commit d86ffe4f5f
1 changed files with 9 additions and 2 deletions
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11
src/lib/Witch/Instances.hs
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@ -251,7 +251,12 @@ instance TryFrom.TryFrom Int.Int64 Word where
-- | Uses 'fromIntegral' when the input is not negative.
instance TryFrom.TryFrom Int.Int64 Natural.Natural where
tryFrom = Utility.eitherTryFrom fromNonNegativeIntegral
-- This should use @eitherTryFrom fromNonNegativeIntegral@, but that causes
-- a bug in GHC 9.0.1.
-- https://mail.haskell.org/pipermail/haskell-cafe/2021-March/133540.html
tryFrom s = case TryFrom.tryFrom (From.from s :: Integer) of
Left (TryFromException.TryFromException _ e) -> Left $ TryFromException.TryFromException s e
Right t -> Right t
-- | Uses 'fromIntegral' when the input is between -16,777,215 and 16,777,215
-- inclusive.
@ -590,7 +595,9 @@ instance TryFrom.TryFrom Word.Word64 Word where
-- | Uses 'fromIntegral'.
instance From.From Word.Word64 Natural.Natural where
from = fromIntegral
-- This should use @fromIntegral@, but that causes a bug in GHC 9.0.1.
-- https://mail.haskell.org/pipermail/haskell-cafe/2021-March/133540.html
from s = Utility.unsafeFrom (From.from s :: Integer)
-- | Uses 'Bits.toIntegralSized'.
instance TryFrom.TryFrom Word.Word64 Int.Int8 where