Stdin.line spins CPU · beginners

Stream: beginners

Topic: Stdin.line spins CPU

JRI98 (Dec 04 2023 at 14:44):

Hello. I don't know if I'm doing something wrong, but the following program makes my CPU spin at 100% before I give it any input. I'm on an M1 MacBook Pro

app "cli-tutorial"
    packages { pf: "https://github.com/roc-lang/basic-cli/releases/download/0.7.0/bkGby8jb0tmZYsy2hg1E_B2QrCgcSTxdUlHtETwm5m4.tar.br" }
    imports [pf.Stdout, pf.Stdin, pf.Task]
    provides [main] to pf

main =
    Task.await Stdin.line \input ->
        when input is
            Input i -> Stdout.line i
            End -> Stdout.line "No input"

Richard Feldman (Dec 04 2023 at 14:45):

huh, that's surprising!

Richard Feldman (Dec 04 2023 at 14:46):

so the program otherwise behaves as expected? (Aside from the 100% CPU before you enter an inputs)

JRI98 (Dec 04 2023 at 14:47):

Wait, I spoke too soon. It is only when running it with the single command roc. No arguments.
And yes, apart from that the program behaves as expected

JRI98 (Dec 04 2023 at 14:50):

roc run main.roc or running the binary from roc build main.rocworks as expected. It's only the two invocations above

Summing up, it is a problem, but only when running roc or roc dev in a folder with a main.roc file with the contents above.
When running roc run main.roc or running the binary from roc build main.roc, the behaviour is as expected and the CPU does not spin.