Hard To Understand Programs

Iain Moncrief

-- CS 581

nats :: [Int]
nats = 1 : map (+1) nats

undefined :: a
undefined = undefined


-- CS 581

class Castable a b where
  cast :: a -> b

instance Castable Int Float where
  cast n = (float)n -- lol

instance Castable Int Double where
  cast n = intToDouble n

{-- Oh no! Some weird error about "undecidability" --}

{--
There is another error message I can't replicate but I see a lot. 
It says something about: Cannot construct infinite type a ~ a' or something weird. 
I still don't know what this means, but once I annotate my function, it almost always goes away.
I have seen it a lot more recently in the recent GHCi versions.
--}

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