[Haskell-cafe] How to print a string (lazily)

Tomasz Zielonka tomasz.zielonka at gmail.com
Wed Jan 4 01:21:13 EST 2006

On Tue, Jan 03, 2006 at 10:28:54PM +0100, Udo Stenzel wrote:
> Daniel Carrera wrote:
> > print_list [] = do putStr ""
> This looks as if you're confused.  The keyword "do" is completely
> redundant.  "do" does not mean "please ignore all rules and allow side
> effects", it rather means "please build a new action by sequencing what
> follows".  So "do" with only one action after it is useless (and a sign
> of confusion).

Perhaps you are right, but this can also be a sign of version-control
awareness, and I know Daniel uses darcs.

I often place a single command in a do-block, because I want future
changes to touch as little lines as possible. Consider:

    f = putStrLn "b"

    f = do
        putStrLn "b"

If you'll later add more commands, you'll get something like:

    f = do
        x <- g
        putStrLn "b"
        putStrLn x

which is much closer to the reduntant-do variant.

Best regards

I am searching for programmers who are good at least in
(Haskell || ML) && (Linux || FreeBSD || math)
for work in Warsaw, Poland

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