CS SYD - How to get the String out of the IO String in Haskell

[NorfairKing]

https://cs-syd.eu/posts/2024-10-02-how-to-get-the-string-out-of-the-io-string

[atravers]

“Inspired” by:

• Haskell Problem (2000 Oct 10)

  Hello,

  I am e-mailing you to see if you could offer me a bit of assistance. I have chosen to use Haskell in a minor assignment at my University, Heriot Watt in Edinburgh. The basic aim is to read in a file of data, sort it and then display it.

  I have managed to get a sort to function properly but I am having trouble with reading in the data from the file. I have managed to use the hGetContents and hGetLine methods of the IO library to read the data in but when it is read in, it is stored as an IO String type.

  I would like to convert the input from the file into one large string so I can process it before sorting it.

  After reading the whole file into a variable, how do I then convert that IO String to a String?

  I would be very grateful if you could offer me some assistance in this matter.

  Thanks

  Graeme Turner

• TIL: haskell is weird for newbies when it comes to IO (2020 Apr 29)

…?

[f-a]

It is a recurring topic when helping newcomers. Multiple good articles cannot do but good.

[treblacy]

I also wrote my I/O tutorial.

But let’s also have some fun:

link to the pic, link to the Gimp xcf file

[atravers]

@f-a

It is a recurring topic when helping newcomers. Multiple good articles cannot do but good.

• IO tutorials timeline

…and from the wiki FAQ:

• How do I convert IO Int to Int?
• How do I convert IO Int to Int inside a pure definition?

---

@treblacy

I also wrote my I/O tutorial.

Someone else wrote a library:

io-machine

---

@treblacy

(IO, String)

…maybe for a comonad tutorial?

[atravers]

But as the widening gap in views of these two topics tend to indicate, this “dyslexic abbreviation” of the original question is more interesting:

How to get Haskell out of I/O?

…so far, the prevailing answer seems to be 무.