[Haskell] Re: IO functions reference?
wchogg at lotus.hep.wisc.edu
Tue Sep 27 10:48:14 EDT 2005
On Tue, 27 Sep 2005, Ketil Malde wrote:
> Creighton Hogg <wchogg at lotus.hep.wisc.edu> writes:
> > So I looked to see if there were any standard functions for
> > taking an input line and turning it into a list, and I
> > couldn't find any. How would one do this in Haskell? I
> > just want to parse the line into a list of strings, and
> > from there recover the numbers from the strings.
> In other words, you want to split "lines" into "words" and "read"
> numbers from the result? Perhaps you should check the Prelude again.
Well don't I feel silly. I'll RTFM next time instead of
just skimming the type signatures.
> > That doesn't seem easy though, unelss there's something I'm
> > missing.
> Reading from and writing to the outside world must take place in the
> IO monad. The parsing and other manipulation can be done by
> functions, use e.g. "let" in the IO code to construct intermediate
> E.g., main can look like:
> main = do
> f <- readFile "table.txt"
> let x = my_parse_function f
> putStrLn x
> my_parse_function :: String -> String
Okay this is a bit more clear to me now, thanks.
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