Bodge together proper checks for dependencies between statements

1 files changed, 169 insertions, 4 deletions

diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerNamespaceTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerNamespaceTests.java
index 03db0b54..e9e5aba5 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerNamespaceTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerNamespaceTests.java
@@ -3,17 +3,17 @@ package org.shedlang.compiler.typechecker;
 import org.junit.jupiter.api.Test;
 import org.shedlang.compiler.ast.untyped.Untyped;
 import org.shedlang.compiler.ast.untyped.UntypedFunctionDefinitionNode;
+import org.shedlang.compiler.typechecker.errors.ReferenceBeforeDefinitionError;
 import org.shedlang.compiler.types.*;
 import org.shedlang.compiler.util.P;
 
 import java.util.List;
 import java.util.Map;
 
-import static org.shedlang.compiler.ast.typed.TypedNodeMatchers.isTypedFunctionDefinitionNode;
-import static org.shedlang.compiler.ast.typed.TypedNodeMatchers.isTypedNamespaceNode;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.shedlang.compiler.ast.typed.TypedNodeMatchers.*;
 import static org.zwobble.precisely.AssertThat.assertThat;
-import static org.zwobble.precisely.Matchers.equalTo;
-import static org.zwobble.precisely.Matchers.isSequence;
+import static org.zwobble.precisely.Matchers.*;
 
 public class TypeCheckerNamespaceTests {
     @Test
@@ -119,6 +119,171 @@ public class TypeCheckerNamespaceTests {
     }
 
     @Test
+    public void functionCanReferenceValDefinedEarlier() {
+        var untyped = Untyped.namespace(List.of(
+            Untyped.val(Untyped.targetVariable("x"), Untyped.boolLiteral(true)),
+            UntypedFunctionDefinitionNode.builder()
+                .withName("f")
+                .withReturnType(Untyped.typeLevelReference("Unit"))
+                .addStatement(Untyped.expressionStatement(Untyped.reference("x")))
+                .build()
+        ));
+        var context = TypeCheckerContext.EMPTY
+            .enterNamespaceWithDefinedVariables(P.map(Map.entry("Unit", Types.metaType(Types.UNIT))));
+
+        var result = TypeChecker.typeCheckNamespace(untyped, context);
+
+        assertThat(
+            result.value(),
+            isTypedNamespaceNode()
+                .withBody(isSequence(
+                        isTypedValNode(isTypedTargetVariable("x"), isTypedBoolLiteralNode(true)),
+                        isTypedFunctionDefinitionNode().withName("f")
+                    )
+                )
+        );
+    }
+
+    @Test
+    public void functionCannotReferenceValDefinedLater() {
+        var untyped = Untyped.namespace(List.of(
+            UntypedFunctionDefinitionNode.builder()
+                .withName("f")
+                .withReturnType(Untyped.typeLevelReference("Unit"))
+                .addStatement(Untyped.expressionStatement(Untyped.reference("x")))
+                .build(),
+            Untyped.val(Untyped.targetVariable("x"), Untyped.boolLiteral(true))
+        ));
+        var context = TypeCheckerContext.EMPTY
+            .enterNamespaceWithDefinedVariables(P.map(Map.entry("Unit", Types.metaType(Types.UNIT))));
+
+        var error = assertThrows(
+            ReferenceBeforeDefinitionError.class,
+            () -> TypeChecker.typeCheckNamespace(untyped, context)
+        );
+
+        assertThat(error.variableName(), equalTo("x"));
+    }
+
+    @Test
+    public void valCanReferenceFunctionDefinedEarlier() {
+        var untyped = Untyped.namespace(List.of(
+            UntypedFunctionDefinitionNode.builder()
+                .withName("f")
+                .withReturnType(Untyped.typeLevelReference("Unit"))
+                .build(),
+            Untyped.val(Untyped.targetVariable("x"), Untyped.call(Untyped.reference("f"), List.of()))
+        ));
+        var context = TypeCheckerContext.EMPTY
+            .enterNamespaceWithDefinedVariables(P.map(Map.entry("Unit", Types.metaType(Types.UNIT))));
+
+        var result = TypeChecker.typeCheckNamespace(untyped, context);
+
+        assertThat(
+            result.value(),
+            isTypedNamespaceNode()
+                .withBody(isSequence(
+                    isTypedFunctionDefinitionNode().withName("f"),
+                    isTypedValNode(isTypedTargetVariable("x"), anything())
+                ))
+        );
+    }
+
+    @Test
+    public void valCanReferenceFunctionDefinedLater() {
+        var untyped = Untyped.namespace(List.of(
+            Untyped.val(Untyped.targetVariable("x"), Untyped.call(Untyped.reference("f"), List.of())),
+            UntypedFunctionDefinitionNode.builder()
+                .withName("f")
+                .withReturnType(Untyped.typeLevelReference("Unit"))
+                .build()
+        ));
+        var context = TypeCheckerContext.EMPTY
+            .enterNamespaceWithDefinedVariables(P.map(Map.entry("Unit", Types.metaType(Types.UNIT))));
+
+        var result = TypeChecker.typeCheckNamespace(untyped, context);
+
+        assertThat(
+            result.value(),
+            isTypedNamespaceNode()
+                .withBody(isSequence(
+                    isTypedValNode(isTypedTargetVariable("x"), anything()),
+                    isTypedFunctionDefinitionNode().withName("f")
+                ))
+        );
+    }
+
+    @Test
+    public void valCanReferenceFunctionThatUsesValDefinedEarlier() {
+        var untyped = Untyped.namespace(List.of(
+            Untyped.val(Untyped.targetVariable("x"), Untyped.boolLiteral(true)),
+            Untyped.val(Untyped.targetVariable("y"), Untyped.call(Untyped.reference("f"), List.of())),
+            UntypedFunctionDefinitionNode.builder()
+                .withName("f")
+                .withReturnType(Untyped.typeLevelReference("Unit"))
+                .addStatement(Untyped.expressionStatement(Untyped.reference("x")))
+                .build()
+        ));
+        var context = TypeCheckerContext.EMPTY
+            .enterNamespaceWithDefinedVariables(P.map(Map.entry("Unit", Types.metaType(Types.UNIT))));
+
+        var result = TypeChecker.typeCheckNamespace(untyped, context);
+
+        assertThat(
+            result.value(),
+            isTypedNamespaceNode()
+                .withBody(isSequence(
+                    isTypedValNode(isTypedTargetVariable("x"), anything()),
+                    isTypedValNode(isTypedTargetVariable("y"), anything()),
+                    isTypedFunctionDefinitionNode().withName("f")
+                ))
+        );
+    }
+
+    @Test
+    public void valCannotReferenceFunctionThatUsesThatVal() {
+        var untyped = Untyped.namespace(List.of(
+            Untyped.val(Untyped.targetVariable("x"), Untyped.call(Untyped.reference("f"), List.of())),
+            UntypedFunctionDefinitionNode.builder()
+                .withName("f")
+                .withReturnType(Untyped.typeLevelReference("Unit"))
+                .addStatement(Untyped.expressionStatement(Untyped.reference("x")))
+                .build()
+        ));
+        var context = TypeCheckerContext.EMPTY
+            .enterNamespaceWithDefinedVariables(P.map(Map.entry("Unit", Types.metaType(Types.UNIT))));
+
+        var error = assertThrows(
+            ReferenceBeforeDefinitionError.class,
+            () -> TypeChecker.typeCheckNamespace(untyped, context)
+        );
+
+        assertThat(error.variableName(), equalTo("x"));
+    }
+
+    @Test
+    public void valCannotReferenceFunctionThatUsesValDefinedLater() {
+        var untyped = Untyped.namespace(List.of(
+            Untyped.val(Untyped.targetVariable("x"), Untyped.call(Untyped.reference("f"), List.of())),
+            Untyped.val(Untyped.targetVariable("y"), Untyped.boolLiteral(true)),
+            UntypedFunctionDefinitionNode.builder()
+                .withName("f")
+                .withReturnType(Untyped.typeLevelReference("Unit"))
+                .addStatement(Untyped.expressionStatement(Untyped.reference("y")))
+                .build()
+        ));
+        var context = TypeCheckerContext.EMPTY
+            .enterNamespaceWithDefinedVariables(P.map(Map.entry("Unit", Types.metaType(Types.UNIT))));
+
+        var error = assertThrows(
+            ReferenceBeforeDefinitionError.class,
+            () -> TypeChecker.typeCheckNamespace(untyped, context)
+        );
+
+        assertThat(error.variableName(), equalTo("y"));
+    }
+
+    @Test
     public void typesOfFieldsAreStored() {
         var namespaceName = NamespaceName.of("Example");
         var untyped = Untyped.namespace(