Add basic type checking for when expressions

9 files changed, 118 insertions, 88 deletions

diff --git a/src/test/java/org/shedlang/compiler/ast/typed/TypedNodeMatchers.java b/src/test/java/org/shedlang/compiler/ast/typed/TypedNodeMatchers.java
index 1f64f631..c5281090 100644
--- a/src/test/java/org/shedlang/compiler/ast/typed/TypedNodeMatchers.java
+++ b/src/test/java/org/shedlang/compiler/ast/typed/TypedNodeMatchers.java
@@ -348,6 +348,27 @@ public class TypedNodeMatchers {
         );
     }
 
+    public static Matcher<TypedExpressionNode> isTypedWhenNode(
+        Matcher<TypedExpressionNode> expression,
+        Matcher<Iterable<? extends TypedWhenCaseNode>> cases
+    ) {
+        return instanceOf(
+            TypedWhenNode.class,
+            has("expression", x -> x.expression(), expression),
+            has("cases", x -> x.cases(), cases)
+        );
+    }
+
+    public static Matcher<TypedWhenCaseNode> isTypedWhenCaseNode(
+        Matcher<TypedTypeLevelExpressionNode<?>> caseType,
+        Matcher<TypedBlockNode> body
+    ) {
+        return allOf(
+            has("caseType", x -> x.caseType(), caseType),
+            has("body", x -> x.body(), body)
+        );
+    }
+
     public static Matcher<TypedFunctionStatementNode> isTypedWhileNode(
         Matcher<? super TypedExpressionNode> condition,
         Matcher<? super TypedBlockNode> body
diff --git a/src/test/java/org/shedlang/compiler/ast/untyped/Untyped.java b/src/test/java/org/shedlang/compiler/ast/untyped/Untyped.java
index 21335011..09067087 100644
--- a/src/test/java/org/shedlang/compiler/ast/untyped/Untyped.java
+++ b/src/test/java/org/shedlang/compiler/ast/untyped/Untyped.java
@@ -207,6 +207,20 @@ public class Untyped {
         return new UntypedAssignNode(targetVal(targetName), expression, Sources.NULL);
     }
 
+    public static UntypedWhenNode when(
+        UntypedExpressionNode expression,
+        List<UntypedWhenCaseNode> cases
+    ) {
+        return new UntypedWhenNode(expression, cases, Sources.NULL);
+    }
+
+    public static UntypedWhenCaseNode whenCase(
+        UntypedTypeLevelExpressionNode caseType,
+        UntypedBlockNode body
+    ) {
+        return new UntypedWhenCaseNode(caseType, body, Sources.NULL);
+    }
+
     public static UntypedWhileNode while_(
         UntypedExpressionNode condition,
         UntypedBlockNode body
diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerAssignTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerAssignTests.java
index cc161b56..ff2e3f1d 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerAssignTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerAssignTests.java
@@ -2,10 +2,8 @@ package org.shedlang.compiler.typechecker;
 
 import org.junit.jupiter.api.Test;
 import org.shedlang.compiler.ast.typed.TypedFunctionStatementNode;
-import org.shedlang.compiler.ast.typed.TypedNamespaceStatementNode;
 import org.shedlang.compiler.ast.untyped.Untyped;
 import org.shedlang.compiler.ast.untyped.UntypedFunctionStatementNode;
-import org.shedlang.compiler.ast.untyped.UntypedNamespaceStatementNode;
 import org.shedlang.compiler.typechecker.errors.CanOnlyAssignToVarError;
 import org.shedlang.compiler.typechecker.errors.TargetTupleHasWrongElementCount;
 import org.shedlang.compiler.typechecker.errors.UnexpectedTypeError;
@@ -177,16 +175,4 @@ public class TypeCheckerAssignTests {
 
         return TypeChecker.typeCheckFunctionStatement(untyped, context);
     }
-
-    private static TypeCheckerResult<? extends TypedNamespaceStatementNode> typeCheckNamespaceStatement(
-        UntypedNamespaceStatementNode untyped,
-        TypeCheckerContext context
-    ) {
-        var declaredVariables = DeclaredVariables.forNamespaceStatement(untyped, P.vector());
-        var environment = EnvironmentBuilder.EMPTY.addUndefined(declaredVariables);
-
-        context = context.enterNamespace(NamespaceName.of("Example"), environment.build());
-
-        return TypeChecker.typeCheckNamespaceStatement(untyped).typeCheckAllPhases(context);
-    }
 }
diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionDefinitionTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionDefinitionTests.java
index d6a600bc..78b89e90 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionDefinitionTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionDefinitionTests.java
@@ -1,13 +1,15 @@
 package org.shedlang.compiler.typechecker;
 
 import org.junit.jupiter.api.Test;
-import org.shedlang.compiler.ast.typed.TypedNamespaceStatementNode;
 import org.shedlang.compiler.ast.untyped.Untyped;
 import org.shedlang.compiler.ast.untyped.UntypedCallNode;
 import org.shedlang.compiler.ast.untyped.UntypedFunctionDefinitionNode;
 import org.shedlang.compiler.typechecker.errors.UnexpectedTypeError;
 import org.shedlang.compiler.typechecker.typesets.TypeSets;
-import org.shedlang.compiler.types.*;
+import org.shedlang.compiler.types.Effects;
+import org.shedlang.compiler.types.FunctionType;
+import org.shedlang.compiler.types.NamedParam;
+import org.shedlang.compiler.types.Types;
 import org.shedlang.compiler.util.P;
 
 import java.util.List;
@@ -15,6 +17,7 @@ import java.util.Map;
 
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.shedlang.compiler.ast.typed.TypedNodeMatchers.*;
+import static org.shedlang.compiler.typechecker.TypeCheckerTesting.typeCheckNamespaceStatement;
 import static org.zwobble.precisely.AssertThat.assertThat;
 import static org.zwobble.precisely.Matchers.*;
 
@@ -383,16 +386,4 @@ public class TypeCheckerFunctionDefinitionTests {
                 )))
         );
     }
-
-    private static TypeCheckerResult<? extends TypedNamespaceStatementNode> typeCheckNamespaceStatement(
-        UntypedFunctionDefinitionNode untyped,
-        TypeCheckerContext context
-    ) {
-        var declaredVariables = DeclaredVariables.forNamespaceStatement(untyped, P.vector());
-        var environment = EnvironmentBuilder.EMPTY.addUndefined(declaredVariables);
-
-        context = context.enterNamespace(NamespaceName.of("Example"), environment.build());
-
-        return TypeChecker.typeCheckNamespaceStatement(untyped).typeCheckAllPhases(context);
-    }
 }
diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerStructDefinitionTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerStructDefinitionTests.java
index 53c5d5e8..344cfa66 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerStructDefinitionTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerStructDefinitionTests.java
@@ -1,9 +1,7 @@
 package org.shedlang.compiler.typechecker;
 
 import org.junit.jupiter.api.Test;
-import org.shedlang.compiler.ast.typed.TypedNamespaceStatementNode;
 import org.shedlang.compiler.ast.untyped.Untyped;
-import org.shedlang.compiler.ast.untyped.UntypedNamespaceStatementNode;
 import org.shedlang.compiler.ast.untyped.UntypedStructDefinitionNode;
 import org.shedlang.compiler.typechecker.errors.CannotDefineStructOutsideOfNamespace;
 import org.shedlang.compiler.types.NamespaceName;
@@ -14,6 +12,7 @@ import java.util.Map;
 
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.shedlang.compiler.ast.typed.TypedNodeMatchers.*;
+import static org.shedlang.compiler.typechecker.TypeCheckerTesting.typeCheckNamespaceStatement;
 import static org.shedlang.compiler.types.TypeMatchers.isStructType;
 import static org.zwobble.precisely.AssertThat.assertThat;
 import static org.zwobble.precisely.Matchers.*;
@@ -30,7 +29,7 @@ public class TypeCheckerStructDefinitionTests {
 
         assertThrows(
             CannotDefineStructOutsideOfNamespace.class,
-            () -> TypeChecker.typeCheckNamespaceStatement(untyped).typeCheckAllPhases(context)
+            () -> TypeChecker.typeCheckStepsNamespaceStatement(untyped).typeCheckAllPhases(context)
         );
     }
 
@@ -126,17 +125,4 @@ public class TypeCheckerStructDefinitionTests {
             ))
         );
     }
-
-    private static TypeCheckerResult<? extends TypedNamespaceStatementNode> typeCheckNamespaceStatement(
-        UntypedNamespaceStatementNode untyped,
-        TypeCheckerContext context
-    ) {
-        // TODO: remove duplication of this method
-        var declaredVariables = DeclaredVariables.forNamespaceStatement(untyped, P.vector());
-        var environment = EnvironmentBuilder.EMPTY.addUndefined(declaredVariables);
-
-        context = context.enterNamespace(NAMESPACE_NAME, environment.build());
-
-        return TypeChecker.typeCheckNamespaceStatement(untyped).typeCheckAllPhases(context);
-    }
 }
diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerSumTypeDefinitionTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerSumTypeDefinitionTests.java
index d70d3660..f93cea14 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerSumTypeDefinitionTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerSumTypeDefinitionTests.java
@@ -1,9 +1,7 @@
 package org.shedlang.compiler.typechecker;
 
 import org.junit.jupiter.api.Test;
-import org.shedlang.compiler.ast.typed.TypedNamespaceStatementNode;
 import org.shedlang.compiler.ast.untyped.Untyped;
-import org.shedlang.compiler.ast.untyped.UntypedNamespaceStatementNode;
 import org.shedlang.compiler.ast.untyped.UntypedSumTypeDefinitionNode;
 import org.shedlang.compiler.typechecker.errors.CannotDefineSumTypeOutsideOfNamespace;
 import org.shedlang.compiler.types.NamespaceName;
@@ -14,6 +12,7 @@ import java.util.Map;
 
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.shedlang.compiler.ast.typed.TypedNodeMatchers.isTypedSumTypeDefinitionNode;
+import static org.shedlang.compiler.typechecker.TypeCheckerTesting.typeCheckNamespaceStatement;
 import static org.zwobble.precisely.AssertThat.assertThat;
 import static org.zwobble.precisely.Matchers.*;
 
@@ -29,7 +28,7 @@ public class TypeCheckerSumTypeDefinitionTests {
 
         assertThrows(
             CannotDefineSumTypeOutsideOfNamespace.class,
-            () -> TypeChecker.typeCheckNamespaceStatement(untyped).typeCheckAllPhases(context)
+            () -> TypeChecker.typeCheckStepsNamespaceStatement(untyped).typeCheckAllPhases(context)
         );
     }
 
@@ -82,17 +81,4 @@ public class TypeCheckerSumTypeDefinitionTests {
             ))
         );
     }
-
-    private static TypeCheckerResult<? extends TypedNamespaceStatementNode> typeCheckNamespaceStatement(
-        UntypedNamespaceStatementNode untyped,
-        TypeCheckerContext context
-    ) {
-        // TODO: remove duplication of this method
-        var declaredVariables = DeclaredVariables.forNamespaceStatement(untyped, P.vector());
-        var environment = EnvironmentBuilder.EMPTY.addUndefined(declaredVariables);
-
-        context = context.enterNamespace(NAMESPACE_NAME, environment.build());
-
-        return TypeChecker.typeCheckNamespaceStatement(untyped).typeCheckAllPhases(context);
-    }
 }
diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerValTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerValTests.java
index 9fd948ba..2688a4c1 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerValTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerValTests.java
@@ -2,8 +2,10 @@ package org.shedlang.compiler.typechecker;
 
 import org.junit.jupiter.api.Test;
 import org.shedlang.compiler.ast.typed.TypedFunctionStatementNode;
-import org.shedlang.compiler.ast.typed.TypedNamespaceStatementNode;
-import org.shedlang.compiler.ast.untyped.*;
+import org.shedlang.compiler.ast.untyped.Untyped;
+import org.shedlang.compiler.ast.untyped.UntypedFunctionDefinitionNode;
+import org.shedlang.compiler.ast.untyped.UntypedFunctionStatementNode;
+import org.shedlang.compiler.ast.untyped.UntypedNamespaceNode;
 import org.shedlang.compiler.typechecker.errors.DuplicateVariableName;
 import org.shedlang.compiler.typechecker.errors.ReferenceBeforeDefinitionError;
 import org.shedlang.compiler.types.NamespaceName;
@@ -14,6 +16,7 @@ import java.util.Map;
 
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.shedlang.compiler.ast.typed.TypedNodeMatchers.*;
+import static org.shedlang.compiler.typechecker.TypeCheckerTesting.typeCheckNamespaceStatement;
 import static org.zwobble.precisely.AssertThat.assertThat;
 import static org.zwobble.precisely.Matchers.*;
 
@@ -157,16 +160,4 @@ public class TypeCheckerValTests {
 
         return TypeChecker.typeCheckFunctionStatement(untyped, context);
     }
-
-    private static TypeCheckerResult<? extends TypedNamespaceStatementNode> typeCheckNamespaceStatement(
-        UntypedNamespaceStatementNode untyped,
-        TypeCheckerContext context
-    ) {
-        var declaredVariables = DeclaredVariables.forNamespaceStatement(untyped, P.vector());
-        var environment = EnvironmentBuilder.EMPTY.addUndefined(declaredVariables);
-
-        context = context.enterNamespace(NamespaceName.of("Example"), environment.build());
-
-        return TypeChecker.typeCheckNamespaceStatement(untyped).typeCheckAllPhases(context);
-    }
 }
diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerVarTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerVarTests.java
index 466ab16c..53e2e65f 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerVarTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerVarTests.java
@@ -2,11 +2,9 @@ package org.shedlang.compiler.typechecker;
 
 import org.junit.jupiter.api.Test;
 import org.shedlang.compiler.ast.typed.TypedFunctionStatementNode;
-import org.shedlang.compiler.ast.typed.TypedNamespaceStatementNode;
 import org.shedlang.compiler.ast.untyped.Untyped;
 import org.shedlang.compiler.ast.untyped.UntypedFunctionDefinitionNode;
 import org.shedlang.compiler.ast.untyped.UntypedFunctionStatementNode;
-import org.shedlang.compiler.ast.untyped.UntypedNamespaceStatementNode;
 import org.shedlang.compiler.types.NamespaceName;
 import org.shedlang.compiler.types.Types;
 import org.shedlang.compiler.util.P;
@@ -14,6 +12,7 @@ import org.shedlang.compiler.util.P;
 import java.util.Map;
 
 import static org.shedlang.compiler.ast.typed.TypedNodeMatchers.*;
+import static org.shedlang.compiler.typechecker.TypeCheckerTesting.typeCheckNamespaceStatement;
 import static org.zwobble.precisely.AssertThat.assertThat;
 import static org.zwobble.precisely.Matchers.anything;
 import static org.zwobble.precisely.Matchers.isSequence;
@@ -65,16 +64,4 @@ public class TypeCheckerVarTests {
 
         return TypeChecker.typeCheckFunctionStatement(untyped, context);
     }
-
-    private static TypeCheckerResult<? extends TypedNamespaceStatementNode> typeCheckNamespaceStatement(
-        UntypedNamespaceStatementNode untyped,
-        TypeCheckerContext context
-    ) {
-        var declaredVariables = DeclaredVariables.forNamespaceStatement(untyped, P.vector());
-        var environment = EnvironmentBuilder.EMPTY.addUndefined(declaredVariables);
-
-        context = context.enterNamespace(NamespaceName.of("Example"), environment.build());
-
-        return TypeChecker.typeCheckNamespaceStatement(untyped).typeCheckAllPhases(context);
-    }
 }
diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerWhenTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerWhenTests.java
new file mode 100644
index 00000000..4fdaf950
--- /dev/null
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerWhenTests.java
@@ -0,0 +1,68 @@
+package org.shedlang.compiler.typechecker;
+
+import org.junit.jupiter.api.Test;
+import org.shedlang.compiler.ast.untyped.Untyped;
+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.*;
+import static org.zwobble.precisely.AssertThat.assertThat;
+import static org.zwobble.precisely.Matchers.isSequence;
+
+public class TypeCheckerWhenTests {
+    private static final NamespaceName NAMESPACE_NAME = NamespaceName.of("Example", "Project");
+    private static final SumType SUM_TYPE = Types.sum(NAMESPACE_NAME, "SumType");
+    private static final StructType VARIANT_TYPE_1 = Types.struct(NAMESPACE_NAME, "Variant1");
+    private static final StructType VARIANT_TYPE_2 = Types.struct(NAMESPACE_NAME, "Variant2");
+
+    @Test
+    public void whenAllCasesAreHandledThenExpressionTypeChecks() {
+        var untyped = Untyped.when(
+            Untyped.reference("x"),
+            List.of(
+                Untyped.whenCase(
+                    Untyped.typeLevelReference(VARIANT_TYPE_1.name()),
+                    Untyped.block(List.of(
+                        Untyped.blockReturn(Untyped.stringLiteral("a"))
+                    ))
+                ),
+                Untyped.whenCase(
+                    Untyped.typeLevelReference(VARIANT_TYPE_2.name()),
+                    Untyped.block(List.of(
+                        Untyped.blockReturn(Untyped.stringLiteral("b"))
+                    ))
+                )
+            )
+        );
+        var context = TypeCheckerContext.EMPTY
+            .addSumTypeInfo(SUM_TYPE, new SumTypeInfo(P.orderedSet(VARIANT_TYPE_1, VARIANT_TYPE_2)))
+            .enterGlobal(P.map(
+                Map.entry("x", SUM_TYPE),
+                Map.entry(VARIANT_TYPE_1.name(), Types.metaType(VARIANT_TYPE_1)),
+                Map.entry(VARIANT_TYPE_2.name(), Types.metaType(VARIANT_TYPE_2))
+            ));
+
+        var result = TypeChecker.typeCheckExpression(untyped, context);
+
+        assertThat(result.value(), isTypedWhenNode(
+            isTypedReferenceNode("x", SUM_TYPE),
+            isSequence(
+                isTypedWhenCaseNode(
+                    isTypedTypeLevelReferenceNode("Variant1", VARIANT_TYPE_1),
+                    isTypedBlockNode(isSequence(
+                        isTypedBlockReturnNode(isTypedStringLiteralNode("a"))
+                    ))
+                ),
+                isTypedWhenCaseNode(
+                    isTypedTypeLevelReferenceNode("Variant2", VARIANT_TYPE_2),
+                    isTypedBlockNode(isSequence(
+                        isTypedBlockReturnNode(isTypedStringLiteralNode("b"))
+                    ))
+                )
+            )
+        ));
+    }
+}