ensuring to receive 4 bytes.

[kazu-yamamoto]

Fix #989.

@mitchellwrosen Would you review this PR?

[mitchellwrosen]

Looks good!

[Vlix]

As long as connRecv always gets an amount of bytes > 0, this should be fine.
If it can produce 0 bytes, then this loop might be infinite (would that result in a timeout?)

What if only 3 bytes were sent?

---

And the L389 bs0 <- recv4 could be replaced with:

bs0 <- connRecv conn >>= loop

So you don't need the recv4 function.

[kazu-yamamoto]

@Vlix I fixed the infinity loop. Please check it again.

[Vlix]

I'd use S.null bs1 to check for empty ByteString, but it looks fine 👍

Also, when doing <> on ByteStrings where one is empty, it just drops it, so it's pretty much as close to efficient as can be. 👍

Using a literal "" will do some unnecessary memory allocation though, it seems, so using S.empty would be more efficient (will just be a static nullForeignPtr which will be dropped at the first <>)

[kazu-yamamoto]

During modification, len is used twice.
But in the current code, I agree that null is better.

[kazu-yamamoto]

Merged.
Thank you for reviewing!