Evaluate error message only after assertion failure in assertEqual

[klntsky]

Another thing that bothers me a little is that the full error message in assertEqual gets evaluated even if it is not needed. show can be quite expensive for large inputs.

Possible fix is to delay the first argument of assert' (some renaming should also be done to avoid breaking the API)

foreign import assert'
  :: (Unit -> String)
  -> Boolean
  -> Effect Unit

Should I make a PR for this issue, or is it too insignificant to care about?

[garyb]

It's not really something I've ever had a problem with personally, printing massive things when assertions fail is probably not so useful when it comes to resolving them 😉

[garyb]

I'll close this for now, we can reopen it if it is a more common concern than I thought.