Question

In Haskell, the following code prints “[1,2,3,4,5”:

foo = take 10 $ show $ numbersFrom 1 where 
  numbersFrom start = start : numbersFrom (start + 1) -- could use [1..]

But in Frege, It throws OutOfMemoryError with the following code:

foo = take 10 $ unpacked $ show $ numbersFrom 1 where
  numbersFrom start = start : numbersFrom (start + 1)

Here the only difference is the unpacked function which is necessary to convert from String to [Char] and FWIW, the unpacked function is eager. Why can’t the whole expression be lazy as in Haskell? Is it possible to achieve something similar to Haskell in Frege here?

Answer 1

I haven’t used Frege, but it seems to me that if unpacked is strict, then its argument ought not be an infinite list. Try unpacked $ take 10 instead of take 10 $ unpacked.