[Haskell-cafe] GHC TV station?

[Matt]

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 at 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 <ietf-dane at dukhovni.org>
> wrote:
>
>>
>>
>> > On May 15, 2018, at 12:13 PM, Sylvester via Haskell-Cafe <
>> haskell-cafe at 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.
>>
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>
>
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