fix: correct type setting for rune characters (#61)

_test/rune0.go

@@ -0,0 +1,37 @@
+package main
+
+import "fmt"
+
+func main() {
+	a := 'r'
+	a += 'g'
+	fmt.Printf("a: %v %T", a, a)
+	fmt.Println()
+
+	b := 'r'
+	b -= 'g'
+	fmt.Printf("b: %v %T", b, b)
+	fmt.Println()
+
+	c := 'r'
+	c *= 'g'
+	fmt.Printf("c: %v %T", c, c)
+	fmt.Println()
+
+	d := 'r'
+	d /= 'g'
+	fmt.Printf("d: %v %T", d, d)
+	fmt.Println()
+
+	e := 'r'
+	e %= 'g'
+	fmt.Printf("e: %v %T", e, e)
+	fmt.Println()
+}
+
+// Output:
+// a: 217 int32
+// b: 11 int32
+// c: 11742 int32
+// d: 1 int32
+// e: 11 int32

interp/ast.go

@@ -465,7 +465,7 @@ func (interp *Interpreter) ast(src, name string) (string, *Node, error) {
 			n.ident = a.Value
 			switch a.Kind {
 			case token.CHAR:
-				n.val = a.Value[1]
+				n.val = rune(a.Value[1])
 			case token.FLOAT:
 				n.val, _ = strconv.ParseFloat(a.Value, 64)
 			case token.IMAG:

interp/interp_test.go

@@ -4102,6 +4102,54 @@ func main() {
 	// 22
 }
 
+func Example_rune0() {
+	src := `
+package main
+
+import "fmt"
+
+func main() {
+	a := 'r'
+	a += 'g'
+	fmt.Printf("a: %v %T", a, a)
+	fmt.Println()
+
+	b := 'r'
+	b -= 'g'
+	fmt.Printf("b: %v %T", b, b)
+	fmt.Println()
+
+	c := 'r'
+	c *= 'g'
+	fmt.Printf("c: %v %T", c, c)
+	fmt.Println()
+
+	d := 'r'
+	d /= 'g'
+	fmt.Printf("d: %v %T", d, d)
+	fmt.Println()
+
+	e := 'r'
+	e %= 'g'
+	fmt.Printf("e: %v %T", e, e)
+	fmt.Println()
+}
+`
+	i := interp.New(interp.Opt{Entry: "main"})
+	i.Use(stdlib.Value, stdlib.Type)
+	_, err := i.Eval(src)
+	if err != nil {
+		panic(err)
+	}
+
+	// Output:
+	// a: 217 int32
+	// b: 11 int32
+	// c: 11742 int32
+	// d: 1 int32
+	// e: 11 int32
+}
+
 func Example_scope0() {
 	src := `
 package main

interp/type.go

@@ -174,6 +174,9 @@ func nodeType(interp *Interpreter, scope *Scope, n *Node) (*Type, error) {
 		case int:
 			t.cat = IntT
 			t.untyped = true
+		case rune:
+			t.cat = RuneT
+			t.untyped = true
 		case string:
 			t.cat = StringT
 			t.untyped = true