Lints and suggestions for the Nix programming language
refactor(eta_reduction): let-else and try-expression
+32
-24
+32
-24
lib/src/lints/eta_reduction.rs
+32
-24
lib/src/lints/eta_reduction.rs
···
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impl Rule for EtaReduction {
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fn validate(&self, node: &SyntaxElement, _sess: &SessionInfo) -> Option<Report> {
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if let NodeOrToken::Node(node) = node
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&& let Some(lambda_expr) = Lambda::cast(node.clone())
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&& let Some(arg_node) = lambda_expr.arg()
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&& let Some(arg) = Ident::cast(arg_node)
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&& let Some(body_node) = lambda_expr.body()
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&& let Some(body) = Apply::cast(body_node)
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&& let Some(value_node) = body.value()
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&& let Some(value) = Ident::cast(value_node)
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&& arg.as_str() == value.as_str()
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&& let Some(lambda_node) = body.lambda()
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&& !mentions_ident(&arg, &lambda_node)
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// lambda body should be no more than a single Ident to
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// retain code readability
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&& let Some(_) = Ident::cast(lambda_node)
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{
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let at = node.text_range();
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let replacement = body.lambda()?;
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let message = format!("Found eta-reduction: `{}`", replacement.text());
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Some(
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self.report()
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.suggest(at, message, Suggestion::new(at, replacement)),
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)
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} else {
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None
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let NodeOrToken::Node(node) = node else {
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return None;
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};
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+
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let lambda_expr = Lambda::cast(node.clone())?;
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let arg_node = lambda_expr.arg()?;
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let arg = Ident::cast(arg_node)?;
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let body_node = lambda_expr.body()?;
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let body = Apply::cast(body_node)?;
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let value_node = body.value()?;
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let value = Ident::cast(value_node)?;
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+
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if arg.as_str() != value.as_str() {
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return None;
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}
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+
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let lambda_node = body.lambda()?;
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+
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if mentions_ident(&arg, &lambda_node) {
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return None;
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}
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+
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// lambda body should be no more than a single Ident to
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// retain code readability
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Ident::cast(lambda_node)?;
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+
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let at = node.text_range();
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let replacement = body.lambda()?;
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let message = format!("Found eta-reduction: `{}`", replacement.text());
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Some(
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self.report()
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.suggest(at, message, Suggestion::new(at, replacement)),
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)
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}
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}
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