Do not run an halogen component when an html element is not present

3
votes

I'm absolutely new to purescript and halogen. I'm trying to display an halogen component (myButton) when an html element exists, and do nothing otherwise.

displayButton :: Eff (HA.HalogenEffects ()) Unit
displayButton = HA.runHalogenAff do
  containerElement <- HA.selectElement (QuerySelector "#halogen-button")
  case containerElement of
    Nothing -> ???
    Just element -> runUI myButton unit element

I don't know what code to put in the Nothing clause so that my code type checks and do nothing in that case.

1
purescripthalogen

1 Answers

1
votes

pure unit is the "do nothing" you could put in. You can also use for_ to make this a little nicer:

for_ containerElement \element ->
  runUI myButton unit element

Which, if you take currying into account is the same as:

for_ containerElement (runUI myButton unit)