Lachlan O'Dea (May 15 2024 at 01:41): Lachlan O'Dea (May 15 2024 at 01:41):This had me scratching my head for a while:
module []
i = Num.toI32 1
# f1 is all fine
f1 = \{ a, b ? "DEFAULT" } -> (a < i, b)
expect f1 { a: 1 } == (Bool.false, "DEFAULT")
expect f1 { a: 1, b: "foo" } == (Bool.false, "foo")
# for f2, the first expect does not compile if the second expect exists
# unless the record parameter is open
f2 : { a : I32, b ? Str } -> (Bool, Str)
f2 = \{ a, b ? "DEFAULT" } -> (a < i, b)
expect f2 { a: 1 } == (Bool.false, "DEFAULT")
expect f2 { a: 1, b: "foo" } == (Bool.false, "foo")
gives:
This 1st argument to f2 has an unexpected type:
17│ expect f2 { a: 1 } == (Bool.false, "DEFAULT")
^^^^^^^^
The argument is a record of type:
{ … }
But f2 needs its 1st argument to be:
{ b : Str, … }
Tip: Looks like the b field is missing.
It works if I change the type to open record f2 : { a : I32, b ? Str }* -> (Bool, Str). This was quite surprising to me based on what the tutorial says about default values.
Brendan Hansknecht (May 15 2024 at 06:05):This is a specialization bug in the compiler
Brendan Hansknecht (May 15 2024 at 06:07):...or, it might not technically be specialization, but definitely a compiler bug
Brendan Hansknecht (May 15 2024 at 06:07):I think there is an issue filed for this, but would need to do some searchin
Lachlan O'Dea (May 15 2024 at 08:05):I had a quick look in the issues and nothing seemed to match, but perhaps I don't know what terminology to look for. Anyway, I'm happy to create an issue if that's useful.
Notification Bot (May 15 2024 at 08:05):Lachlan O'Dea has marked this topic as resolved.
Brendan Hansknecht (May 15 2024 at 08:06):Yeah, please make one. Someone can dedupe if there happens to be another match
Lachlan O'Dea (May 15 2024 at 08:21):https://github.com/roc-lang/roc/issues/6750
Last updated: Jul 26 2025 at 12:14 UTC