Dynamically constructed []string has type of []interface

[daisy1754]

I want to implement an expression that returns slice of string. expr properly gives []string when it's immediate value eg ["a"] but when I do something like [str] it gives type []interface even though str is string. Below is code to reproduce behaviour. Ideally I want all cases below to return []string

package main

import (
	"fmt"
	"github.com/antonmedv/expr"
)

func main() {
	env := map[string]interface{}{
		"arr": []string{"a","b"},
		"s": "s",
	}

	
	p1, _ := expr.Compile(`arr`, expr.Env(env))
	o1, _ := expr.Run(p1, env)
	fmt.Printf("%T", o1) // []string
	
	p2, _ := expr.Compile(`[arr[0]]`, expr.Env(env))
	o2, _ := expr.Run(p2, env)
	fmt.Printf("%T", o2) // []interface
	
	p3, _ := expr.Compile(`["a"]`, expr.Env(env))
	o3, _ := expr.Run(p3, env)
	fmt.Printf("%T", o3) // []string
	
	p4, _ := expr.Compile(`[s]`, expr.Env(env))
	o4, _ := expr.Run(p4, env)
	fmt.Printf("%T", o4) // []interface
}

[antonmedv]

Currently expr constructs [] as interface. In case of using ["a"] there is optimisation which replaces it with precomputed constant and alter type. Maybe this. An be extended to alter type in case of string vars too.

[antonmedv]

Fixed! Now always []any!