Re: [Haskell-cafe] GHC TV station?

15 May 2018


      Could you link to a GitHub gist or lambdapaste or similar? I don't see a
plaintext attachment.

Matt Parsons

On Tue, May 15, 2018 at 11:01 AM, Sylvester Hazel via Haskell-Cafe <
haskell-cafe@haskell.org> wrote:
...
Hi Victor,
It is frustrating that posting plain text is contorted (via nabble.com
and then again in my mail.google.com account) - please see the
attachment.
I really have sent the right indentation copping the Hutton's script.
Is it so difficult for you guys to replicate this obvious failure of GHC
on "do notation" with white space?
Regards,
Sylvester
On Tue, May 15, 2018 at 6:27 PM, Viktor Dukhovni 
wrote:
...
...
On May 15, 2018, at 12:13 PM, Sylvester via Haskell-Cafe <
haskell-cafe@haskell.org> wrote:
strlen in Hutton 2ed 10.5 Derived primitives => run on Windows 7 Haskell
Platform 8.2.2
strlen :: IO ()
strlen = do  putStr "Enter a string: "
                  xs <-  getLine
                  putStr "The string has "
                  putStr (show (length xs))
                  putStr " characters"
===================================================
The above indentation looks wrong.  Try:
----------
$ cat foo.hs
strlen :: IO ()
strlen = do putStr "Enter a string: "
            xs <-  getLine
            putStr "The string has "
            putStr (show (length xs))
            putStrLn " characters"
$ ghci foo.hs
GHCi, version 8.0.2: http://www.haskell.org/ghc/  :? for help
[1 of 1] Compiling Main             ( foo.hs, interpreted )
Ok, modules loaded: Main.
Loaded GHCi configuration from /tmp/haskell-stack-ghci/054851
25/ghci-script
*Main> strlen
Enter a string: foo
The string has 3 characters
*Main>
----------
If I incorrectly indent the subsequent lines:
strlen :: IO ()
strlen = do putStr "Enter a string: "
              xs <-  getLine
              putStr "The string has "
              putStr (show (length xs))
              putStrLn " characters"
Then I see an error:
foo.hs:2:13: error:
    Parse error in pattern: putStr
    Possibly caused by a missing 'do'?
--
        Viktor.
_______________________________________________
Haskell-Cafe mailing list
To (un)subscribe, modify options or view archives go to:
http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
Only members subscribed via the mailman list are allowed to post.
_______________________________________________
Haskell-Cafe mailing list
To (un)subscribe, modify options or view archives go to:
http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
Only members subscribed via the mailman list are allowed to post.