diff --git a/internal/backends/compiler_wat/compile.go b/internal/backends/compiler_wat/compile.go
index 40fda0f..911572e 100644
--- a/internal/backends/compiler_wat/compile.go
+++ b/internal/backends/compiler_wat/compile.go
@@ -42,6 +42,13 @@ func (p *Compiler) Compile(prog *loader.Program, mainFunc string) (output string
 	}
 	sort.Strings(pkgnames)
 
+	for i, v := range pkgnames {
+		if v == "runtime" && i != 0 {
+			pkgnames[i] = pkgnames[0]
+			pkgnames[0] = "runtime"
+		}
+	}
+
 	for _, n := range pkgnames {
 		p.ssaPkg = prog.Pkgs[n].SSAPkg
 		p.CompilePkgConst(p.ssaPkg)
diff --git a/internal/backends/compiler_wat/compile_func.go b/internal/backends/compiler_wat/compile_func.go
index 3f57c22..8de39ca 100644
--- a/internal/backends/compiler_wat/compile_func.go
+++ b/internal/backends/compiler_wat/compile_func.go
@@ -359,6 +359,10 @@ func (g *functionGenerator) genValue(v ssa.Value) ([]wat.Inst, wir.ValueType) {
 	//	logger.Printf("Instruction already exist：%s\n", v)
 	//}
 
+	if v, ok := v.(*ssa.Range); ok {
+		return g.genRange(v)
+	}
+
 	//Todo: 下面的做法过于粗暴
 	g.tLib.compile(v.Type())
 
@@ -419,6 +423,9 @@ func (g *functionGenerator) genValue(v ssa.Value) ([]wat.Inst, wir.ValueType) {
 
 	case *ssa.TypeAssert:
 		return g.genTypeAssert(v)
+
+	case *ssa.Next:
+		return g.genNext(v)
 	}
 
 	logger.Fatalf("Todo: %v, type: %T", v, v)
@@ -1142,6 +1149,22 @@ func (g *functionGenerator) genTypeAssert(inst *ssa.TypeAssert) (insts []wat.Ins
 	return
 }
 
+func (g *functionGenerator) genRange(inst *ssa.Range) (insts []wat.Inst, ret_type wir.ValueType) {
+	x := g.getValue(inst.X)
+	return g.module.EmitGenRange(x.value)
+}
+
+func (g *functionGenerator) genNext(inst *ssa.Next) (insts []wat.Inst, ret_type wir.ValueType) {
+	if inst.IsString {
+		ret_type = g.tLib.compile(inst.Type())
+		iter := g.getValue(inst.Iter).value
+		insts = g.module.EmitGenNext_String(iter)
+	} else {
+		logger.Fatalf("Todo:%T", inst.Type())
+	}
+	return
+}
+
 func (g *functionGenerator) addRegister(typ wir.ValueType) wir.Value {
 	defer func() { g.cur_local_id++ }()
 	name := "$t" + strconv.Itoa(g.cur_local_id)
diff --git a/internal/backends/compiler_wat/wir/instruction_emitter.go b/internal/backends/compiler_wat/wir/instruction_emitter.go
index 04936d0..1129641 100644
--- a/internal/backends/compiler_wat/wir/instruction_emitter.go
+++ b/internal/backends/compiler_wat/wir/instruction_emitter.go
@@ -16,8 +16,8 @@ func (m *Module) EmitAssginValue(lh, rh Value) []wat.Inst {
 		insts = append(insts, lh.EmitRelease()...)
 		insts = append(insts, lh.EmitInit()...)
 	} else {
-		if !lh.Type().Equal(rh.Type()) {
-			logger.Fatal("x.Type() != y.Type()")
+		if !lh.Type().Equal(rh.Type()) && !(lh.Type().Equal(m.I32) && rh.Type().Equal(m.RUNE) || lh.Type().Equal(m.RUNE) && rh.Type().Equal(m.I32)) {
+			logger.Fatal("x.Type:", lh.Type().Name(), ", y.Type():", rh.Type().Name())
 		}
 
 		insts = append(insts, rh.EmitPush()...)
@@ -893,6 +893,28 @@ func (m *Module) EmitGenTypeAssert(x Value, destType ValueType, commaOk bool) (i
 	}
 }
 
+func (m *Module) EmitGenRange(x Value) (insts []wat.Inst, ret_type ValueType) {
+	switch x := x.(type) {
+	case *aString:
+		ret_type, _ = m.findValueType("runtime.stringIter")
+		insts = append(insts, x.Extract("d").EmitPush()...)
+		insts = append(insts, x.Extract("l").EmitPush()...)
+		insts = append(insts, wat.NewInstConst(wat.I32{}, "0"))
+
+	default:
+		logger.Fatalf("Todo:%T", x)
+	}
+
+	return
+}
+
+func (m *Module) EmitGenNext_String(iter Value) (insts []wat.Inst) {
+	insts = append(insts, iter.EmitPush()...)
+	insts = append(insts, wat.NewInstCall("runtime.next_rune"))
+	insts = append(insts, iter.(*aStruct).Extract("pos").EmitPop()...)
+	return
+}
+
 func (m *Module) EmitInvoke(i Value, params []Value, mid int, typeName string) (insts []wat.Inst) {
 	iface := i.(*aInterface)
 	insts = append(insts, iface.Extract("d").EmitPush()...)
diff --git a/waroot/src/runtime/runtime.wa b/waroot/src/runtime/runtime.wa
index d8998bb..a3bbb64 100644
--- a/waroot/src/runtime/runtime.wa
+++ b/waroot/src/runtime/runtime.wa
@@ -163,3 +163,43 @@ func refToPtr_byteSlice(t: []byte) => i32 {
 func refToPtr_string(s: string) => i32 {
 	return U8_string_to_ptr(s)
 }
+
+type stringIter struct {
+	ptr: uint
+	len: int
+	pos: int
+}
+
+#wa:runtime_getter
+func get_u8(p: u32) => u8
+
+#wa:runtime_setter
+func set_u8(p: u32, v: u8)
+
+func next_rune(iter: stringIter) => (ok: bool, k: int, v: rune, pos: int) {
+	if iter.pos >= iter.len {
+		return false, iter.pos, 0, iter.pos
+	}
+
+	p0 := i32(get_u8(u32(iter.ptr) + u32(iter.pos)))
+	if p0 & 0b10000000 == 0 {
+		return true, iter.pos, rune(p0), iter.pos + 1
+	} else if p0 & 0b11100000 == 0b11000000 {
+		p0 = (p0 & 0b11111) << 6
+		p1 := i32(get_u8(u32(iter.ptr) + u32(iter.pos) + 1)) & 0b00111111
+		return true, iter.pos, rune(p0 | p1), iter.pos + 2
+	} else if p0 & 0b11110000 == 0b11100000 {
+		p0 = (p0 & 0b1111) << 12
+		p1 := (i32(get_u8(u32(iter.ptr) + u32(iter.pos) + 1)) & 0b00111111) << 6
+		p2 := (i32(get_u8(u32(iter.ptr) + u32(iter.pos) + 2)) & 0b00111111)
+		return true, iter.pos, rune(p0 | p1 | p2), iter.pos + 3		
+	} else if p0 & 0b11111000 == 0b11110000 {
+		p0 = (p0 & 0b111) << 18
+		p1 := (i32(get_u8(u32(iter.ptr) + u32(iter.pos) + 1)) & 0b00111111) << 12
+		p2 := (i32(get_u8(u32(iter.ptr) + u32(iter.pos) + 2)) & 0b00111111) << 6
+		p3 := (i32(get_u8(u32(iter.ptr) + u32(iter.pos) + 3)) & 0b00111111)
+		return true, iter.pos, rune(p0 | p1 | p2 | p3), iter.pos + 4
+	}
+
+	return
+}