add union type

src/main/java/org/yinwang/yin/Scope.java

@@ -137,6 +137,34 @@ public static Scope buildInitScope() {
     }
 
 
+    public static Scope buildInitTypeScope() {
+        Scope init = new Scope();
+
+//        init.putValue("+", new Add());
+//        init.putValue("-", new Sub());
+//        init.putValue("*", new Mult());
+//        init.putValue("/", new Div());
+//
+//        init.putValue("<", new Lt());
+//        init.putValue("<=", new LtE());
+//        init.putValue(">", new Gt());
+//        init.putValue(">=", new GtE());
+//        init.putValue("=", new Eq());
+//        init.putValue("and", new And());
+//        init.putValue("or", new Or());
+//        init.putValue("not", new Not());
+
+        init.putValue("true", new BoolType());
+        init.putValue("false", new BoolType());
+
+//        init.putValue("Int", new IntType());
+//        init.putValue("Bool", new BoolType());
+//        init.putValue("String", new StringType());
+
+        return init;
+    }
+
+
     public void put(String name, String key, Object value) {
         Map<String, Object> item = table.get(name);
         if (item == null) {

src/main/java/org/yinwang/yin/TypeChecker.java

@@ -15,15 +15,15 @@ public TypeChecker(String file) {
     }
 
 
-    public Value interp(String file) {
+    public Value typecheck(String file) {
         Node program = Parser.parse(file);
-        return program.typecheck(Scope.buildInitScope());
+        return program.typecheck(Scope.buildInitTypeScope());
     }
 
 
     public static void main(String[] args) {
         TypeChecker i = new TypeChecker(args[0]);
-        Value result = i.interp(args[0]);
+        Value result = i.typecheck(args[0]);
         _.msg(result.toString());
     }
 

src/main/java/org/yinwang/yin/ast/If.java

@@ -3,7 +3,9 @@
 import org.yinwang.yin.Constants;
 import org.yinwang.yin.Scope;
 import org.yinwang.yin._;
+import org.yinwang.yin.value.BoolType;
 import org.yinwang.yin.value.BoolValue;
+import org.yinwang.yin.value.UnionType;
 import org.yinwang.yin.value.Value;
 
 public class If extends Node {
@@ -37,7 +39,14 @@ public Value interp(Scope s) {
 
     @Override
     public Value typecheck(Scope s) {
-        return null;
+        Value tv = typecheck(test, s);
+        if (!(tv instanceof BoolType)) {
+            _.abort(test, "test is not boolean: " + tv);
+            return null;
+        }
+        Value thenType = typecheck(then, s);
+        Value elseType = typecheck(orelse, s);
+        return UnionType.union(thenType, elseType);
     }
 
 

src/main/java/org/yinwang/yin/ast/Name.java

@@ -28,7 +28,13 @@ public Value interp(Scope s) {
 
     @Override
     public Value typecheck(Scope s) {
-        return null;
+        Value v = s.lookup(id);
+        if (v != null) {
+            return v;
+        } else {
+            _.abort(this, "unbound variable: " + id);
+            return Value.VOID;
+        }
     }
 
 

src/main/java/org/yinwang/yin/ast/Node.java

@@ -34,6 +34,11 @@ public static Value interp(Node node, Scope s) {
     public abstract Value typecheck(Scope s);
 
 
+    public static Value typecheck(Node node, Scope s) {
+        return node.typecheck(s);
+    }
+
+
     public static List<Value> interpList(List<Node> nodes, Scope s) {
         List<Value> values = new ArrayList<>();
         for (Node n : nodes) {

src/main/java/org/yinwang/yin/value/UnionType.java

@@ -0,0 +1,59 @@
+package org.yinwang.yin.value;
+
+
+import org.yinwang.yin.Constants;
+
+import java.util.HashSet;
+import java.util.Set;
+
+public class UnionType extends Value {
+
+    public Set<Value> values = new HashSet<>();
+
+
+    public UnionType() {
+
+    }
+
+
+    public static UnionType union(Value... values) {
+        UnionType u = new UnionType();
+        for (Value v : values) {
+            u.add(v);
+        }
+        return u;
+    }
+
+
+    public void add(Value value) {
+        if (value instanceof UnionType) {
+            values.addAll(((UnionType) value).values);
+        } else {
+            values.add(value);
+        }
+    }
+
+
+    public int size() {
+        return values.size();
+    }
+
+
+    public String toString() {
+        StringBuilder sb = new StringBuilder();
+        sb.append(Constants.TUPLE_BEGIN).append("U ");
+
+        boolean first = true;
+        for (Value v : values) {
+            if (!first) {
+                sb.append(" ");
+            }
+            sb.append(v);
+            first = false;
+        }
+
+        sb.append(Constants.TUPLE_END);
+        return sb.toString();
+    }
+
+}

tests/typecheck1.yin

@@ -1,2 +1,5 @@
 10
 "ok"
+true
+
+(if true 10 "ok")