[Haskell-cafe] (no subject)

Don Stewart dons at galois.com
Fri Aug 21 18:42:21 EDT 2009

> Hi, I'm just started to learn Haskell. Coming from a programming contest
> background (where it is important to be able to solve problems in a small
> amount of code) I'm wondering what the best way is for simple IO.
> A typical input file (in a programming contest) is just a bunch of numbers
> which you want to read one by one (sometimes interspersed with strings). In
> C/C++ this is easily done with either scanf or cin which reads data
> separated by spaces. In Haskell I have not found an equally satisfactionary
> method. The methods I know of
> 1) Stay in the IO monad and write your own readInt readString functions. A lot
> of code for something easy.
> 2) Use interact together with words and put the list of lexemes in a State
> monad and define getInt where at least you can use read.
> 3) Use ByteString.Char8 which has readInt (but I couldn't find a
> readString). But one has to put it also in a State monad.
> I think that there must be standard function that can do this. What do
> experienced Haskellers use?

    map read . lines

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