Re: [Haskell-cafe] Best way to format a number

briqueabraque:

Hi,

I would like to get a string for a number using always 2 digits (i.e., 75 would be "75", 3 would became "03"). What is the best way to do that? I tried

printf "%02d\n" 3

which gives me the correct string, but ghci always ends that call with a

*** Exception: Prelude.undefined

message. What else should I try? Can Text.PrettyPrint do that?

It's to do with ghci's defaulting. This is fixed in ghc 6.8: Prelude Text.Printf> printf "%02d\n" 3 03 You can work around it for now with: Prelude Text.Printf> printf "%02d\n" 3 >> return () 03 -- Don