mirror of
https://github.com/roc-lang/roc.git
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cc3423a709
The ? operator now desugars expr? to a match expression that unwraps Ok
values and early returns Err values:
match expr {
Ok(#ok) => #ok,
Err(#err) => return Err(#err),
}
Implementation details:
- Use pre-interned identifiers (#ok, #err) for synthetic variables
- Use pre-interned Ok/Err tag names from CommonIdents
- Create applied_tag patterns for Ok and Err
- Build match branches with proper scope isolation
- Mark synthetic patterns as used to avoid unused variable warnings
- Create e_lookup_local, e_tag, and e_return expressions for branch bodies
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
19 lines
459 B
Text
19 lines
459 B
Text
app [main!] { pf: platform "./platform/main.roc" }
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import pf.Stdout
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# Tests the `?` operator for error propagation.
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# The operator unwraps Ok values or early-returns Err values.
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get_greeting : {} -> Try(Str, [ListWasEmpty])
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get_greeting = |{}| {
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first = List.first(["hello"])?
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Ok(first)
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}
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main! = || {
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match get_greeting({}) {
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Ok(greeting) => Stdout.line!(greeting)
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Err(ListWasEmpty) => Stdout.line!("List was empty!")
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}
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}
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