How to implement constraints for reducers, etc.

Maybe it’s just my newness to the Elm Architecture, but I’m having a hard time figuring out how to do constraints with reducers, etc. For example, in the GoMix todo example when you click the button, it adds a todo whether the input has a value or not. For keyup I can put a constraint like this:

// If the input has value and the user hits Enter, add todo.
onkeyup={e => (e.keyCode === 13 && e.target.value) ? actions.add() : ""}

But for the button click that won’t work because it doesn’t have access to the input value. Old school way would be on button click check value of input, if it has a value, do stuff, otherwise not. How do you do that with this pattern? This would also come up with form validation. 🤔

[rbiggs]

Yeah, I was thinking an effect was the way to go, but I wan’t sure. Thanx. 🍺🍻

[tunnckoCore]

@dodekeract 👍

@rbiggs it sounds to me like an effect too. Make an effect, then just pass e to it, and do you checking and all that stuff there, not in the view part.