Luke Boswell (Dec 16 2023 at 09:40): Luke Boswell (Dec 16 2023 at 09:40):What's it called when you can use single quotes ' to directly refer to a byte like 'a' gives 97 : Int * etc. I couldn't find it in the tutorial from a quick scan. I'm not sure where I learnt that from.
The reason I bring this up is because it caught me out for an hour or so today when I used a utf8 two byte character in this way and Roc didnt complain, so I didn't realise that something fishy was going on.
I'm using the following character. I have no idea why the unicode data files chose to use this (and some other strange ones) for segmenting information in their data files
Screenshot-2023-12-16-at-20.39.11.png
» Str.toUtf8 "×"
[195, 151] : List U8
» '×'
215 : Int *
Should that second operation using single quotes not be permitted in Roc?
Richard Feldman (Dec 16 2023 at 11:24):so single quotes compile to the Unicode Code Point, not (necessarily, except by coincidence) utf8
Richard Feldman (Dec 16 2023 at 11:25):when the code point is less than 128, it'll be one utf8 byte, but any code point of 128 or higher needs 2+ utf8 bytes to represent
Richard Feldman (Dec 16 2023 at 11:26):so this looks likely correct to me (although I can definitely see why it would be surprising!)
Luke Boswell (Dec 16 2023 at 11:27):Thats actually much more helpful for what I need. For some reason I thought it was only ASCII permitted
Brendan Hansknecht (Dec 16 2023 at 15:12):Is 215 the correct value though? It's too small to be 2 byte
Richard Feldman (Dec 16 2023 at 15:29):utf8 encodes anything over 127 in 2+ bytes
Brendan Hansknecht (Dec 16 2023 at 15:30):Oh, its not the literally 2byte value cast to an int?
Richard Feldman (Dec 16 2023 at 15:40):correct, it's the Unicode Code Point - which is a single integer
Richard Feldman (Dec 16 2023 at 15:40):correct, it's the Unicode Code Point - which is a single integer
Richard Feldman (Dec 16 2023 at 15:40):as Luke noted, that tends to be the useful thing in practice :big_smile:
Brendan Hansknecht (Dec 16 2023 at 15:41):casting the 2 byte value to an int is also a single integer
Brendan Hansknecht (Dec 16 2023 at 15:42):Would be 50071 in this case
Brendan Hansknecht (Dec 16 2023 at 15:43):Or 38851 if the bytes need to be reversed due to endian handling
Brendan Hansknecht (Dec 16 2023 at 15:45):Oh yeah, codepoint it what number it would be in utf32. Which is different than having the utf8 bytes cast to a single integer.
Brendan Hansknecht (Dec 16 2023 at 15:47):Cause currently, utf8 is also limited to 4 bytes, so you could just cast it to a U32 to make it a single integer. Though if utf expands enough, theoretically, utf8 could have values larger than 4 bytes.
Last updated: Jul 06 2025 at 12:14 UTC