Stream: beginners

Topic: ✔ Trouble importing another Roc file

Ian McLerran (Jan 11 2024 at 14:03):

Suppose I have two Roc files - one defines an interface, and another an app. I want to import my interface into my app.
The interface (BinaryTree.roc) looks like:

interface BinaryTree
    exposes [
        Tree, Node, Null, listToTree, hasLhs, hasRhs,
    ]
# rest of roc code ...

And the complete app (LeafSimilar.roc) code is:

app "leafsimilar"
    packages { pf: "https://github.com/roc-lang/basic-cli/releases/download/0.7.1/..." }
    imports [
        pf.Stdout,
        BinaryTree.{
            Tree,
            Node,
            Null,
            listToTree,
            hasLhs,
            hasRhs
        }
    ]
    provides [main] to pf

main = Stdout.line "Hello, world!"

But when I run roc dev LeafSimilar.roc, I get an error message that doesn't make much sense to me:

── WEIRD IMPORTS ────────────────────────────────────────────── BinaryTree.roc ─

I am partway through parsing a header, but I got stuck here:

10│      ]
          ^

I am expecting the imports keyword next, like

    imports [Animal, default, tame]

I'm not finding much documentation on how to do imports, but from the examples I've looked at, I think my import statement looks good, also the error message doesn't really make sense, as I see no reason that it would expect the imports statement next, on line 10, after my existing imports statement. Any help?

Brian Carroll (Jan 11 2024 at 14:18):

At the top right of the error message it shows the filename BinaryTree.roc. Can you also show us the full header of that file?

Brian Carroll (Jan 11 2024 at 14:20):

Without seeing it, my guess is that you might need to add an empty imports?

Ian McLerran (Jan 11 2024 at 14:24):

That was it - thanks!

Notification Bot (Jan 11 2024 at 14:25):

Ian McLerran has marked this topic as resolved.

Brian Carroll (Jan 11 2024 at 18:59):

Maybe the filename is too easy to miss in our error message layout?

Last updated: Jul 26 2025 at 12:14 UTC