Hi Adithya, The representations are the same. You can do this. I do this somewhat often. Just avoid mutating in places where it could result in funky stuffs. This is usually pretty easy to spot. Cheers, chessai On Mon, Jul 24, 2023, 12:59 Adithya Kumar wrote:

Hello all,

I have a use-case where I want to convert `ByteArray#` to `MutableByteArray#` without the copy overhead.

Is the underlying memory structure of `ByteArray#` and `MutableByteArray#` the same?

If I can guarantee that I won't mutate my `MutableByteArray#`, can I use `unsafeCoerce#` on `ByteArray#` and treat it as `MutableByteArray#`?

Best, Adithya _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs

Adithya Kumar writes:

Hello all,

I have a use-case where I want to convert `ByteArray#` to `MutableByteArray#` without the copy overhead.

Is the underlying memory structure of `ByteArray#` and `MutableByteArray#` the same?

If I can guarantee that I won't mutate my `MutableByteArray#`, can I use `unsafeCoerce#` on `ByteArray#` and treat it as `MutableByteArray#`?

Note that a future release of GHC (IIRC 9.10) will have a (no-op) operation for precisely this purpose. See [1]. Cheers, - Ben [1] https://gitlab.haskell.org/ghc/ghc/-/issues/22710