Parse function signatures without return type

4 files changed, 32 insertions, 2 deletions

diff --git a/src/test/java/org/shedlang/compiler/ast/untyped/UntypedFunctionSignatureNodeMatcher.java b/src/test/java/org/shedlang/compiler/ast/untyped/UntypedFunctionSignatureNodeMatcher.java
index d799245b..8cd1c638 100644
--- a/src/test/java/org/shedlang/compiler/ast/untyped/UntypedFunctionSignatureNodeMatcher.java
+++ b/src/test/java/org/shedlang/compiler/ast/untyped/UntypedFunctionSignatureNodeMatcher.java
@@ -7,7 +7,7 @@ import org.zwobble.precisely.Matcher;
 
 import java.util.Optional;
 
-import static org.zwobble.precisely.Matchers.has;
+import static org.zwobble.precisely.Matchers.*;
 
 public class UntypedFunctionSignatureNodeMatcher extends MatcherBuilder<
     UntypedFunctionSignatureNode,
@@ -44,7 +44,19 @@ public class UntypedFunctionSignatureNodeMatcher extends MatcherBuilder<
         return with(has("params", x -> x.params(), params));
     }
 
-    public UntypedFunctionSignatureNodeMatcher withReturnType(Matcher<UntypedTypeLevelExpressionNode> returnType) {
+    public UntypedFunctionSignatureNodeMatcher withReturnType(
+        Matcher<UntypedTypeLevelExpressionNode> returnType
+    ) {
+        return withReturnTypeOptional(isOptionalOf(returnType));
+    }
+
+    public UntypedFunctionSignatureNodeMatcher withoutReturnType() {
+        return withReturnTypeOptional(isOptionalEmpty());
+    }
+
+    private UntypedFunctionSignatureNodeMatcher withReturnTypeOptional(
+        Matcher<Optional<? extends UntypedTypeLevelExpressionNode>> returnType
+    ) {
         return with(has("returnType", x -> x.returnType(), returnType));
     }
 }
diff --git a/src/test/java/org/shedlang/compiler/parser/ParserFunctionSignatureTests.java b/src/test/java/org/shedlang/compiler/parser/ParserFunctionSignatureTests.java
index cfb610af..797d112d 100644
--- a/src/test/java/org/shedlang/compiler/parser/ParserFunctionSignatureTests.java
+++ b/src/test/java/org/shedlang/compiler/parser/ParserFunctionSignatureTests.java
@@ -180,4 +180,17 @@ public class ParserFunctionSignatureTests {
                 .withReturnType(isUntypedTypeLevelReferenceNode("Unit"))
         );
     }
+
+    @Test
+    public void canParseSignatureWithoutReturnType() {
+        var source = "()";
+
+        var node = parseString(source, Parser::parseFunctionSignature);
+
+        assertThat(
+            node,
+            isUntypedFunctionSignatureNode()
+                .withoutReturnType()
+        );
+    }
 }
diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerValTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerValTests.java
index d8c98535..3f2adf5d 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerValTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerValTests.java
@@ -48,6 +48,7 @@ public class TypeCheckerValTests {
     @Test
     public void valCanBeReferencedAfterDefinitionInFunction() {
         var untyped = UntypedFunctionDefinitionNode.builder()
+            .withReturnTypeUnit()
             .addStatement(Untyped.assign(Untyped.targetVal("x"), Untyped.stringLiteral("hello")))
             .addStatement(Untyped.expressionStatement(Untyped.reference("x")))
             .build();
@@ -94,6 +95,7 @@ public class TypeCheckerValTests {
     @Test
     public void valCannotBeReferencedBeforeDefinition() {
         var untyped = UntypedFunctionDefinitionNode.builder()
+            .withReturnTypeUnit()
             .addStatement(Untyped.expressionStatement(Untyped.reference("x")))
             .addStatement(Untyped.assign(Untyped.targetVal("x"), Untyped.stringLiteral("hello")))
             .build();
@@ -113,6 +115,7 @@ public class TypeCheckerValTests {
     @Test
     public void whenValShadowsExistingVariableThenValCannotBeReferencedBeforeDefinition() {
         var untyped = UntypedFunctionDefinitionNode.builder()
+            .withReturnTypeUnit()
             .addStatement(Untyped.expressionStatement(Untyped.reference("x")))
             .addStatement(Untyped.assign(Untyped.targetVal("x"), Untyped.stringLiteral("hello")))
             .build();
@@ -133,6 +136,7 @@ public class TypeCheckerValTests {
     @Test
     public void duplicateVariableNamesAreNotAllowed() {
         var untyped = UntypedFunctionDefinitionNode.builder()
+            .withReturnTypeUnit()
             .addStatement(Untyped.assign(Untyped.targetVal("x"), Untyped.stringLiteral("hello")))
             .addStatement(Untyped.assign(Untyped.targetVal("x"), Untyped.stringLiteral("hello")))
             .build();
diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerVarTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerVarTests.java
index 5efdd2c5..0443802f 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerVarTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerVarTests.java
@@ -33,6 +33,7 @@ public class TypeCheckerVarTests {
     @Test
     public void varCanBeReferencedAfterDefinitionInFunction() {
         var untyped = UntypedFunctionDefinitionNode.builder()
+            .withReturnTypeUnit()
             .addStatement(Untyped.assign(Untyped.targetVar("x"), Untyped.stringLiteral("hello")))
             .addStatement(Untyped.expressionStatement(Untyped.reference("x")))
             .build();