From e38dd0cd24e76e91918273b08a6e9ede9d542e93 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Sun, 29 Oct 2023 21:58:22 +0000
Subject: Infer named param types from hint

---
 .../shedlang/compiler/typechecker/TypeChecker.java | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

(limited to 'src/main/java')

diff --git a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
index eec4a8be..9e37666c 100644
--- a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
+++ b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
@@ -688,16 +688,28 @@ public class TypeChecker {
             positionalParams.add(param);
         }
 
-        var partialSignatureParams = new ArrayList<>(positionalParams);
+        var namedParams = new ArrayList<PartialFunctionSignature.Param>();
 
         for (var namedParam : typedSignature.params().named()) {
-            partialSignatureParams.add(new PartialFunctionSignature.Param(
+            var paramHint = functionTypeHint.flatMap(
+                h -> h.namedParams().stream()
+                    .filter(p -> p.name().equals(namedParam.name()))
+                    .map(p -> p.type())
+                    .findFirst()
+            );
+
+            namedParams.add(new PartialFunctionSignature.Param(
                 namedParam.name(),
-                namedParam.type().orElseThrow().value(),
+                namedParam.type()
+                    .map(x -> x.value())
+                    .or(() -> paramHint)
+                    .orElseThrow(),
                 namedParam.source()
             ));
         }
 
+        var partialSignatureParams = Lists.concat(positionalParams, namedParams);
+
         var effect = functionSignatureToEffect(typedSignature);
 
         var partialSignature = new PartialFunctionSignature(
@@ -718,7 +730,9 @@ public class TypeChecker {
             positionalParams.stream()
                 .map(x -> x.type())
                 .toList(),
-            functionSignatureToNamedParams(typedSignature),
+            namedParams.stream()
+                .map(x -> new NamedParam(x.name(), x.type()))
+                .toList(),
             effect,
             typedBody.type()
         );
-- 
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