Ian McLerran (Jan 21 2025 at 15:04): Ian McLerran (Jan 21 2025 at 15:04):I think I'm probably miss understanding how to accumulate errors, but I have an error message I can't quite figure out.
What confuses me here is that it is complaining about the annotation of my error type, but I actually replaced my error type annotation with a []_ to try to get it to type check. Here is the error message:
Something is off with the body of the to_str definition:
22│ to_str : List U16 -> Result Str []_ #[BadUtf16 Utf16Problem, BadUtf8 Utf8.Utf8Problem]
23│ to_str = |utf16|
24│ codepoints = to_codepoints(utf16)?
^^^^^^^^^^^^^^^^^^^^^
This returns an Err of type:
[
Err [BadUtf16 Utf16Problem],
Ok Str,
]
But the type annotation on to_str says it should be:
Result Str [BadUtf8 {
index : U64,
problem : Utf8ByteProblem,
}]
The relevant code is as follows:
to_codepoints : List U16 -> Result (List U32) [BadUtf16 Utf16Problem]
to_str : List U16 -> Result Str []_ #[BadUtf16 Utf16Problem, BadUtf8 Utf8.Utf8Problem]
to_str = |utf16|
codepoints = try to_codepoints(utf16) # annotation above
codepoints # List U32
|> Utf8.from_codepoints # List U32 -> List U8
|> Str.from_utf8 # List U8 -> Result Str [BadUtf8 Utf8.Utf8Problem]
Does just _ work instead of []_?
Ian McLerran (Jan 21 2025 at 17:13):Same thing. And removing the type annotation entirely doesn't work either. It produces a slightly different error.
Last updated: Jul 26 2025 at 12:14 UTC