Provide a way to define types via expr

[antonmedv]

Now expr inherits types from "example" env. I may be cool to have a API to define types explicitly.

[antonmedv]

We can introduce those:

• types.Map: for giving a hint of map fields.
• types.StrictMap: field hints, plus only defined keys are allowed.

[staugaard]

This would be a great feature. Any plans of implementing this?

[antonmedv]

Yes, this feature on the roadmap.

[antonmedv]

	env := types.StrictMap{
		"foo": types.StrictMap{
			"bar": types.Int,
		},
	}