Formatter option is now composed of two data: flags (lower 16 bits) and indentation size (higher 16 bits).

DictType and ListType formatter use both indent and flag options.
Simple-store now makes a DictType from its data and its ToString() function returns dict.ToString()

simple-store.go

@@ -7,7 +7,7 @@ package expr
 import (
 	"fmt"
 	"slices"
-	"strings"
+//	"strings"
 )
 
 type SimpleStore struct {
@@ -50,7 +50,7 @@ func (ctx *SimpleStore) Merge(src ExprContext) {
 		ctx.funcStore[name], _ = src.GetFuncInfo(name)
 	}
 }
-
+/*
 func varsCtxToBuilder(sb *strings.Builder, ctx ExprContext, indent int) {
 	sb.WriteString("vars: {\n")
 	first := true
@@ -116,6 +116,49 @@ func (ctx *SimpleStore) ToString(opt FmtOpt) string {
 	funcsCtxToBuilder(&sb, ctx, 0)
 	return sb.String()
 }
+*/
+
+func (ctx *SimpleStore) ToString(opt FmtOpt) string {
+	dict := ctx.ToDict()
+	return dict.ToString(opt)
+}
+
+func (ctx *SimpleStore) varsToDict(dict *DictType) *DictType {
+	names := ctx.EnumVars(nil)
+	slices.Sort(names)
+	for _, name := range ctx.EnumVars(nil) {
+		value, _ := ctx.GetVar(name)
+		if f, ok := value.(Formatter); ok {
+			(*dict)[name] = f.ToString(0)
+		} else if _, ok = value.(Functor); ok {
+			(*dict)[name] = "func(){}"
+		} else {
+			(*dict)[name] = fmt.Sprintf("%v", value)
+		}
+	}
+	return dict
+}
+
+func (ctx *SimpleStore) funcsToDict(dict *DictType) *DictType {
+	names := ctx.EnumFuncs(func(name string) bool { return true })
+	slices.Sort(names)
+	for _, name := range names {
+		value, _ := ctx.GetFuncInfo(name)
+		if formatter, ok := value.(Formatter); ok {
+			(*dict)[name] = formatter.ToString(0)
+		} else {
+			(*dict)[name] = fmt.Sprintf("%v", value)
+		}
+	}
+	return dict
+}
+
+func (ctx *SimpleStore) ToDict() (dict *DictType) {
+	dict = MakeDict()
+	(*dict)["variables"] = ctx.varsToDict(MakeDict())
+	(*dict)["functions"] = ctx.funcsToDict(MakeDict())
+	return
+}
 
 func (ctx *SimpleStore) GetVar(varName string) (v any, exists bool) {
 	v, exists = ctx.varStore[varName]