Re: primitive (byte) string literal with length?

On Tue, Aug 24, 2021 at 08:48:53AM +0200, Sylvain Henry wrote:

Le 24 août 2021 à 06:34, à 06:34, Viktor Dukhovni a écrit:

...

Is there any GHC syntax for constructing a primitive string literal with a known (not hand coded) byte count? With `"some bytes"#` I get just the `Addr#` pointer, but not the size.

If there's nothing available, would it be reasonable to introduce a new syntax? Perhaps:

"some bytes"## :: (# Addr#, Int# #)

You can use cstringLength# which has a constant-folding rules for literals. That's what we use in GHC to build FastString literals.

Sadly, that does not work when the primitive octet string contains internal NUL bytes. λ> :set -package ghc-prim λ> :set -XMagicHash λ> import GHC.CString λ> import GHC.Int λ> λ> I# (cstringLength# "foobar\xa0"#) 7 λ> I# (cstringLength# "foo\0bar\xa0"#) 3 -- Viktor.