Hello!
On Haskell for Mac version 1.5.0 (1336 MAS) based on GHC 8.0.2
Start a new project, and add the following to your Main.hs:
main = putStrLn $ show 368.0
Add this to your playground pane:
main
Click on the button to show your console, and you will see in your console:
3.0
Which is obviously incorrect! What's going on here?
Thank you very much for reporting this admittedly rather weird bug. It will be fixed in the next release.
I am sorry for the inconvenience in the meantime.
PS: If you are curious how this behaviour could arise — which baffled me at first. HfM makes sure to interpret backspace characters in console output properly as a control character. Now, due to changes in the `String` API in the migration to Swift 3, code that was supposed to check for backspace (ASCII value 8) does now check for the digit `8`.
I should add that there's something special about the number 368, and other numbers with the same mantissa - 3.68, 36.8…
You'll see correct behaviour with other numbers.
The bug seems to have nothing to do with Fractional or numbers at all. I was able to reproduce this just with Strings, and with many other values besides those related to "368", e.g.:
putStrLn "348"
prints the following in the console:
3
and
putStrLn "489"
prints
9
and
putStrLn "48"
prints nothing at all.
The same behavior is seen using `putStr` and `print`.
This is in Haskell for Mac 1.5.0.
Thanks Manuel. In the meantime, is there a workaround?
Tushar, I know this is super annoying and I am very sorry about it, but unfortunately, I don't see a workaround. (This does only affect output to the console and not results displayed on the right hand side of the playground.)
I'll make sure to put out a bug fix update soon.