Implement main expressions #168
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BinderDavid
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Mar 22, 2024
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BinderDavid
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app/src/cli/run.rs
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| match nf { | ||
| Some(nf) => print_nf(&nf), | ||
| None => { | ||
| println!("No \"main\" expression was found in the program.") |
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eprintln! to print to stderr or better return Err(...) to print to stderr and exit with status code 1.
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As discussed, we should split pol run into pol check and pol run. I can do that in a separate PR.
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I have implemented both check and run in this PR, and use a miette error to report if a main expression wasn't found.
| impl<P: Phase> Let<P> { | ||
| /// Returns whether the declaration is the "main" expression of the module. | ||
| pub fn is_main(&self) -> bool { | ||
| self.name == "main" && self.params.is_empty() |
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We should probably forbid parameters on let bindings called main during lowering.
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Reasoning: otherwise it is confusing for users because they will see the error message "main not found" but they have a main expression with a different signature.
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| impl<P: Phase> Let<P> { | ||
| /// Returns whether the declaration is the "main" expression of the module. | ||
| pub fn is_main(&self) -> bool { | ||
| self.name == "main" && self.params.is_empty() |
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Reasoning: otherwise it is confusing for users because they will see the error message "main not found" but they have a main expression with a different signature.
- `pol run` executes the main expression in a file - `pol check` only typechecks a file
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I have added a help message to the error: david@anaxes ~/polarity/polarity (add-main-functions)$ pol run examples/example.pol
Error: × Main expression was not found
help: Main expressions must be called "main" and not take any arguments.
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