✔ Best way to introspect (debug) Roc programs · beginners

Stream: beginners

Topic: ✔ Best way to introspect (debug) Roc programs

Dan (Jan 09 2024 at 23:24):

Is there any way to debug my Roc programs until I will start understanding them properly?

Currently I would love to have something like

log(typeof (EXPRESSION))

so Roc compiler/runtime will show me some info about expression or variable (like in REPL).
Or what are the workaround/advices?

Thanks.

Agus Zubiaga (Jan 09 2024 at 23:37):

You can make a def and give it any type annotation:

whatIsThis : {}
whatIsThis = { x : 32, y : "hello" }

Then the compiler will print the inferred type when it finds the mismatch:

── TYPE MISMATCH ──────────────────────────────────────────────────── Test.roc ─

Something is off with the body of the whatIsThis definition:

3│  whatIsThis : {}
4│  whatIsThis = { x : 32, y : "hello" }
                 ^^^^^^^^^^^^^^^^^^^^^^^

The body is a record of type:

    {
        x : Num *,
        y : Str,
    }

But the type annotation on whatIsThis says it should be:

    {}


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