Add lazy

[tesk9]

Adds lazy helper to support recursive controls.

Adds an example view, although I'm not sure it adds much value. Would happily delete again if you'd like.

One 💭 I had was to maybe change Control from:

type Control a
    = Control
        { currentValue : () -> a
        , allValues : () -> List a
        , view : () -> ControlView a
        }

to

type Control a
    = Control (() -> 
            { currentValue : a
            , allValues : List a
            , view : ControlView a
            }

[avh4]

Regarding changing Control to Control (() -> { ... } instead of having the functions inside of the record fields, that sounds okay, except the reason allValues was already a lazy function is because computing allValues can be very expensive, so I don't want it to be computed except where it's needed, so if you wanted to go that route, I'd want to see something like

type Control a
    = Control (() -> 
            { currentValue : a
            , allValues : () -> List a
            , view : ControlView a
            }

with allValues still being lazier than the rest of the fields.

[avh4]

Looks good! The new example seems fine to keep.

Could you add some testing maybe similar to the new recursive type example along the lines of https://github.com/avh4/elm-debug-controls/blob/master/tests/Controls/ComplexChoiceTest.elm ?

And also, lazy will need some documentation.

[tesk9]

@avh4 Turns out that allValues exploded with recursive values, which makes sense. How important is to have an allValues function, do you think? I don't see how allValues and lazy can both be exposed, you know?

I tried removing allValues, and I think it works (changes the API of list a bit tho). What do you think?

[avh4]

Turns out that allValues exploded with recursive values

This means just that you can't call allValues on the control for the recursive type you defined, or that you couldn't actually implement lazy with the new types? If it's the former, I think it's best to keep it and just expect that it won't work for infinitely recursive controls.

(The purpose of allValues was for something like in a style guide where it could render the view with all the different values that could be selected so that you could quickly scroll through and visually ok them all without having to manually select each state from the interactive controls.)

[tesk9]

Yeah, it's the former. I'll undo the removal then!

[avh4]

Thanks! I'll try to remember to look at this tomorrow. (I think it should be good, though.)

[avh4]

Thanks!

[tesk9]

Thank you!!!