Rauny (Jun 11 2024 at 06:12): Rauny (Jun 11 2024 at 06:12):Hey, noob here. I'm going through the tutorial but got stuck trying to understand why I have this error with the following code:
app [main] {
pf: platform "https://github.com/roc-lang/basic-cli/releases/download/0.10.0/vNe6s9hWzoTZtFmNkvEICPErI9ptji_ySjicO6CkucY.tar.br",
}
import pf.Stdout
import pf.Task
# main : Task.Task {} _
main =
Stdout.line! "Hello, World!"
res1 = "test"
Stdout.line! "Hello, World! $(res1)"
res2 =
["a", "b", "c"]
|> List.append "d"
|> Str.joinWith ""
Stdout.line! res2
res3 =
(["a", "b", "c"])
|> List.append "d"
|> Str.joinWith ""
but, if I change it to this, it works
app [main] {
pf: platform "https://github.com/roc-lang/basic-cli/releases/download/0.10.0/vNe6s9hWzoTZtFmNkvEICPErI9ptji_ySjicO6CkucY.tar.br",
}
import pf.Stdout
import pf.Task
# main : Task.Task {} _
main =
Stdout.line! "Hello, World!"
res1 = "test"
Stdout.line! "Hello, World! $(res1)"
res2 =
["a", "b", "c"]
|> List.append "d"
|> Str.joinWith ""
Stdout.line! res2
res3 =
(["a", "b", "c"])
|> List.append "d"
|> Str.joinWith ""
Stdout.line! res3
Roc version: roc nightly pre-release, built from commit 0e1a9545c6c on Sat Jun 8 09:11:54 UTC 2024
Any help or explanation is appreciated. Thank you!
Brendan Hansknecht (Jun 11 2024 at 06:21):Fundamentally, basic cli requires that main returns a task.
Brendan Hansknecht (Jun 11 2024 at 06:22):With the first example, the last thing you do is assign a variable instead of returning a task
Brendan Hansknecht (Jun 11 2024 at 06:22):With the second example, you end with a !. ! ends up building up a chain of tasks.
Brendan Hansknecht (Jun 11 2024 at 06:23):So ending with Stdout.line! res3 will return the full chain of tasks, with the last task being printing res3
Rauny (Jun 11 2024 at 07:05):oh ok, it's clear now, thank you so much!
Notification Bot (Jun 11 2024 at 07:05):Rauny has marked this topic as resolved.
Last updated: Jul 26 2025 at 12:14 UTC