Type annotated main ending in `!` does not compile · beginners

Stream: beginners

Topic: Type annotated main ending in `!` does not compile

Ian McLerran (Sep 25 2024 at 18:14):

Not sure if this has already been addressed in another thread, but there is currently a bug which causes a roc program who's main function is type annotated, and ends in a ! operator to fail to compile:

So this does not compile:

main : Task {} _
main = Stdout.line! "Hello, world!"

But both of these do:

main : Task {} _
main = Stdout.line "Hello, world!"

main = Stdout.line! "Hello, world!"

Ian McLerran (Sep 25 2024 at 18:15):

The error message produced is the following:

Error message:

── NAMING PROBLEM in x.roc ──

This annotation does not match the definition immediately following
it:

7│> main : Task {} _
8│> main =
9│> Stdout.line! "Hello, world!"

Is it a typo? If not, put either a newline or comment between them.

── UNRECOGNIZED NAME in x.roc ──

Nothing is named #!1_expr in this scope.

9│ Stdout.line! "Hello, world!"
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Did you mean one of these?

Integer
Hasher
Box
I128

Kilian Vounckx (Sep 25 2024 at 20:37):

I think there was already a thread somewhere about it. Not sure though. If I recall correctly, it is not only with main, but any function with a single statement which ends in a '!'.

Luke Boswell (Sep 25 2024 at 21:04):

I think I know where the issue is roughly... though got distracted and havent looked at it since I made the comment.

https://github.com/roc-lang/roc/issues/7103

Last updated: Jul 26 2025 at 12:14 UTC