[Haskell-cafe] error on "--++ bla bla bla"

Alexander Dunlap alexander.dunlap at gmail.com
Wed Sep 30 23:57:10 EDT 2009


Oops...forgot the footnote. The lexical syntax part of the report is
at http://haskell.org/onlinereport/lexemes.html.

Alex

On Wed, Sep 30, 2009 at 7:56 PM, Alexander Dunlap
<alexander.dunlap at gmail.com> wrote:
> Comments are started with "--" followed by a character that is not a
> symbol character. If it is followed by a symbol character (e.g. "*")
> then the "--" plus the symbol (e.g. "--*") parses as an operator
> rather than a comment. "p" is not a symbol, so the "--" starts a
> comment.
>
> For a precise description of Haskell syntax, see the Haskell98
> Report[1]. It's quite readable, at least in comparison to other
> "precise" documents I've attempted to read.
>
> Hope that helps.
>
> Alex
>
> On Wed, Sep 30, 2009 at 7:48 PM, Hong Yang <hyangfji at gmail.com> wrote:
>> Nowhere any Haskell book mentioned "line comments start with "-- ", not just
>> "--"." It is just people usually put "-- " ahead of comments.
>>
>> I can successfully compile "--print bla bla bla."
>> On Wed, Sep 30, 2009 at 7:36 PM, Sebastian Sylvan
>> <sebastian.sylvan at gmail.com> wrote:
>>>
>>>
>>> On Thu, Oct 1, 2009 at 12:52 AM, Hong Yang <hyangfji at gmail.com> wrote:
>>>>
>>>> Hi,
>>>>
>>>> I got an error if one of lines reads "--++ bla bla bla" where I tried to
>>>> comment, but "-- ++ bla bla bla" (notice the space after "--") is OK.
>>>>
>>>> Do you think this revealed a tiny bug in the GHC compiler (I am using
>>>> Windows Haskell Platform 2009.2.0.2)?
>>>
>>> Line comments start with "-- ", not just "--".
>>> --
>>> Sebastian Sylvan
>>
>>
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>>
>


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