GitLab

For a long time GHC had no first-class sized integer types. While Word8 existed, it was merely a wrapper around Word# with the invariant that the value was a byte. This changed in 2c959a18 and 36fcf9ed with the introduction of {Word,Int}{16,32}#, giving us a full complement of sized integer types.

In !4390 (closed) we adjusted the lifted Data.Int and Data.Word types to use their sized unlifted types (e.g. Word8#) instead of their word-sized brethren (e.g. Word#). However, this is just the first step of this process. There are a variety of knock-on effects that will also need to be pushed forward,

• readWord8OffAddr# and friends still return unsized results (!4492)
• indexWord8OffAddr# and friends still return unsized results (!4492)
• writeWord8OffAddr# and friends still take unsized arguments (!4492)
• the type mappings INT_VECTOR_TYPES and WORD_VECTOR_TYPES defined in primops.txt.pp still used unsized types (!4492)
• the ByteArray# operations still use unsized types (!4492)
• we do not have binary operations (e.g. +#, and#) for the sized types (!4717)

Also

• 64-bit types are annoying to work with because CPP. (!3658, has its own issues too.)