From dab3e3e24b485e732c9419620557c5f83ff7984e Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Fri, 28 Aug 2026 19:18:53 +0100
Subject: Pass supplier for each type param in arbitrary generic native func

---
 .../zwobble/example/types/map/HobgoblinNativeMap.java |  7 ++++++-
 .../example/types/data/HobgoblinNativeData.java       |  9 +++++++--
 .../compiler/analysis/ArbitraryValueAnalysis.java     | 19 ++++++++++++++++---
 .../generators/javatypes/JavaTypesGenerator.java      |  9 ++++++++-
 4 files changed, 37 insertions(+), 7 deletions(-)

diff --git a/examples/12-native-type-generic/output/java/src/main/java/org/zwobble/example/types/map/HobgoblinNativeMap.java b/examples/12-native-type-generic/output/java/src/main/java/org/zwobble/example/types/map/HobgoblinNativeMap.java
index 309ba0b..39fd627 100644
--- a/examples/12-native-type-generic/output/java/src/main/java/org/zwobble/example/types/map/HobgoblinNativeMap.java
+++ b/examples/12-native-type-generic/output/java/src/main/java/org/zwobble/example/types/map/HobgoblinNativeMap.java
@@ -1,9 +1,14 @@
 package org.zwobble.example.types.map;
 
+import java.util.function.Supplier;
+
 public class HobgoblinNativeMap {
     private HobgoblinNativeMap() {}
 
-    public static <K, V> java.util.Map<K, V> arbitraryNativeMap() {
+    public static <K, V> java.util.Map<K, V> arbitraryNativeMap(
+        Supplier<K> supplyK,
+        Supplier<V> supplyV
+    ) {
         return new java.util.HashMap<>();
     }
 }
diff --git a/examples/16-transient-0/output/java/src/main/java/org/zwobble/example/types/data/HobgoblinNativeData.java b/examples/16-transient-0/output/java/src/main/java/org/zwobble/example/types/data/HobgoblinNativeData.java
index 32796b5..cc26b7b 100644
--- a/examples/16-transient-0/output/java/src/main/java/org/zwobble/example/types/data/HobgoblinNativeData.java
+++ b/examples/16-transient-0/output/java/src/main/java/org/zwobble/example/types/data/HobgoblinNativeData.java
@@ -1,5 +1,7 @@
 package org.zwobble.example.types.data;
 
+import java.util.function.Supplier;
+
 public class HobgoblinNativeData {
     private HobgoblinNativeData() {}
 
@@ -7,7 +9,10 @@ public class HobgoblinNativeData {
         return new Native(0, 0);
     }
 
-    public static <A, B> GenericNative<A, B> arbitraryGenericNative() {
-        throw new RuntimeException("TODO");
+    public static <A, B> GenericNative<A, B> arbitraryGenericNative(
+        Supplier<A> supplyA,
+        Supplier<B> supplyB
+    ) {
+        return new GenericNative<>(supplyA.get(), supplyB.get());
     }
 }
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/analysis/ArbitraryValueAnalysis.java b/src/main/java/org/zwobble/hobgoblin/compiler/analysis/ArbitraryValueAnalysis.java
index 650e753..6664538 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/analysis/ArbitraryValueAnalysis.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/analysis/ArbitraryValueAnalysis.java
@@ -15,9 +15,15 @@ public class ArbitraryValueAnalysis {
     public sealed interface ArbitraryValue {
         void collectTypeParams(Set<TypeParam> typeParams);
 
-        record NativeFunctionCall(SimpleNativeType type) implements ArbitraryValue {
+        record NativeFunctionCall(
+            SimpleNativeType type,
+            List<ArbitraryValue> args
+        ) implements ArbitraryValue {
             @Override
             public void collectTypeParams(Set<TypeParam> typeParams) {
+                for (var arg : args) {
+                    arg.collectTypeParams(typeParams);
+                }
             }
         }
 
@@ -79,7 +85,14 @@ public class ArbitraryValueAnalysis {
                     yield new ArbitraryValue.Shared(arbitraryValue(constructedNativeType.args().getFirst(), typesInfo));
                 }
 
-                yield new ArbitraryValue.NativeFunctionCall(constructedNativeType.constructor().genericType());
+                var args = constructedNativeType.args().stream()
+                    .map(argType -> arbitraryValue(argType, typesInfo))
+                    .toList();
+
+                yield new ArbitraryValue.NativeFunctionCall(
+                    constructedNativeType.constructor().genericType(),
+                    args
+                );
             }
 
             case ConstructedStructType constructedStructType -> {
@@ -106,7 +119,7 @@ public class ArbitraryValueAnalysis {
                 new ArbitraryValue.EnumVariantValue(enumType, typesInfo.enumVariants(enumType).getFirst());
 
             case SimpleNativeType simpleNativeType ->
-                new ArbitraryValue.NativeFunctionCall(simpleNativeType);
+                new ArbitraryValue.NativeFunctionCall(simpleNativeType, List.of());
 
             case SimpleStructType simpleStructType ->
                 new ArbitraryValue.SimpleStructBuilder(simpleStructType);
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatypes/JavaTypesGenerator.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatypes/JavaTypesGenerator.java
index 3143905..814fe4b 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatypes/JavaTypesGenerator.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatypes/JavaTypesGenerator.java
@@ -692,7 +692,14 @@ public class JavaTypesGenerator implements Generator {
                             JavaTypeRef.topLevel(javaPackageName, javaClassName),
                             List.of(),
                             generateFieldName("arbitrary" + simpleNativeType.name()),
-                            List.of()
+                            nativeFunctionCall.args().stream()
+                                .<JavaExpression>map(arg -> new JavaLambdaExpression(
+                                    List.of(),
+                                    new JavaBlock(List.of(
+                                        new JavaReturn(abstractArbitraryValueToJava(arg, context))
+                                    ))
+                                ))
+                                .toList()
                         );
                     });
             }
-- 
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