make eta_reduction less aggressive (#76)

Co-authored-by: Stephan Maka <[email protected]>
nerdypepper · Jul 5, 2023 · bcb3d10 · bcb3d10
1 parent 3c7136a
commit bcb3d10
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Showing 2 changed files with 7 additions and 1 deletion.
diff --git a/bin/tests/data/eta_reduction.nix b/bin/tests/data/eta_reduction.nix
@@ -15,4 +15,7 @@ in
 
  # other non-free forms
  (map (f: {inherit f;}.double f.val) [ f ])
+
+ # don't reduce on more complex lambda bodies
+ (map (x: builtins.div 3 x) xs)
 ]
diff --git a/lib/src/lints/eta_reduction.rs b/lib/src/lints/eta_reduction.rs
@@ -56,10 +56,13 @@ impl Rule for EtaReduction {
  if let Some(value_node) = body.value();
  if let Some(value) = Ident::cast(value_node);
 
- if arg.as_str() == value.as_str() ;
+ if arg.as_str() == value.as_str();
 
  if let Some(lambda_node) = body.lambda();
  if !mentions_ident(&arg, &lambda_node);
+ // lambda body should be no more than a single Ident to
+ // retain code readability
+ if let Some(_) = Ident::cast(lambda_node);
 
  then {
  let at = node.text_range();