Playground result is different from the real library

[madesst]

I think I found a small issue. The official playground seems to give a different answer than when I use the library in my go code.

Here's my code:

	evalResult, err := expr.Eval("type($env['date'])", map[string]interface{}{"date": "2025-11-12T12:12:12Z"})
	if err != nil {
		panic(err)
	}
	fmt.Println(evalResult)

It returns a string as evalResult
go playground

And here's a screenshot from the expr playground where it returns time.Time for the same expression:

I thought they should both work the same way. Is this a bug or did I miss something?

[antonmedv]

Yes! This is a special playground "feature". As we do not have an env type in playground, it guesses the time. In case of a string in JSON looking as time, playground will convert it to time.Time.

To make your local example work, provide time.Time object to the env.

[madesst]

I am passing a complex object into the env and I don't want rewrite every possible timestamp-string into a time.Time. What I would like instead is the ability to debug the expression in the same way it would behave at runtime.

It is not very clear why the behavior here is different - it feels a bit like if the go playground behaved differently than go itself :DD

[antonmedv]

I see. I'm actually thinking to create a separate playground subproject where you can bring your own envs.