The following test is done with `ghc-9.6.6`.
```
{-# LANGUAGE UnboxedTuples #-}
{-# LANGUAGE MagicHash #-}
import GHC.Base (IO(..))
import GHC.Exts
import Prelude hiding (length)
data MutByteArray = MutByteArray (MutableByteArray# RealWorld)
{-# INLINE new #-}
new :: Int -> IO MutByteArray
new (I# nbytes) = IO $ \s ->
case newByteArray# nbytes s of
(# s', mbarr# #) ->
let c = MutByteArray mbarr#
in (# s', c #)
{-# INLINE length #-}
length :: MutByteArray -> IO Int
length (MutByteArray arr) =
IO $ \s ->
case getSizeofMutableByteArray# arr s of
(# s1, i #) -> (# s1, I# i #)
test1 :: IO ()
test1 = do
val <- new (-7)
len <- length val
print len
test2 :: IO ()
test2 = do
val <- new (-8)
len <- length val
print len
```
`test1` succeeds and prints `-7`
The test prints the length for all `>= -7`
`test2` fails with `Out of memory`
If `length <= -8`, the test fails with `Out of memory`
This is an interesting quirk.
I expected `newByteArray#` to fail if the size given to it is `< 0` and I
never
expected `getSizeofMutableByteArray#` would return a negative number.
Best,
Adithya
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