[GregBuchholz]

>in Haskell, by default you can't compare an Optional with the value it wraps: `5 == Just 5` fails.

    -- Probably nothing like in Swift
    instance (Num a , Integral a) => Num (Maybe a) where
        fromInteger x = Just (fromIntegral x)
        
    main = print $ 5 == (Just 5)

[majewsky]

This only works because you're working with number literals here, which have the very liberal type "Num a => a". If I replace your main function by

  check :: Int -> Bool
  check x = x == (Just x)

  main = print (check 5)

I get a compile error:

  Main.hs:7:17: error:
      • Couldn't match expected type ‘Int’ with actual type ‘Maybe Int’
      • In the second argument of ‘(==)’, namely ‘(Just x)’
        In the expression: x == (Just x)
        In an equation for ‘check’: check x = x == (Just x)

[GregBuchholz]

Right, it was just a fun little "Well Actually" moment.

http://tirania.org/blog/archive/2011/Feb-17.html

[wyager]

That is possibly the most condescending thing I've ever read. Whatever the author tried to make themselves less abrasive, it didn't work very well.