add Accessor to uniqueness typecheck

src/uniqueness/mod.rs

@@ -6,6 +6,7 @@ use crate::can::procedure::{Procedure, References};
 use crate::can::symbol::Symbol;
 use crate::collections::{ImMap, SendMap};
 // use crate::constrain::{self, exists};
+use crate::can::ident::Lowercase;
 use crate::can::pattern;
 use crate::ident::Ident;
 use crate::region::{Located, Region};
@@ -518,6 +519,32 @@ pub fn canonicalize_expr(
 
             (output, And(constraints))
         }
+
+        Accessor(name) => {
+            let ext_var = var_store.fresh();
+            let ext_type = Variable(ext_var);
+
+            let field_var = var_store.fresh();
+            let field_type = Variable(field_var);
+
+            let mut field_types = SendMap::default();
+            let field_name: Lowercase = name.clone().into();
+            field_types.insert(field_name, field_type.clone());
+            let record_type =
+                constrain::lift(var_store, Type::Record(field_types, Box::new(ext_type)));
+
+            (
+                Output::default(),
+                exists(
+                    vec![field_var, ext_var],
+                    Eq(
+                        Type::Function(vec![record_type], Box::new(field_type)),
+                        expected,
+                        region,
+                    ),
+                ),
+            )
+        }
         _ => panic!("{:?}", expr),
     }
 }

tests/test_uniqueness_infer.rs

@@ -867,6 +867,9 @@ mod test_infer_uniq {
             "Attr.Attr * Int",
         );
     }
-    /*
-     */
+
+    #[test]
+    fn accessor_function() {
+        infer_eq(".foo", "Attr.Attr * { foo : a }* -> a");
+    }
 }