[Haskell-cafe] Comment Syntax

[Malcolm Wallace]

>> -- followed by a symbol does not start a comment, thus for example, haddock
>> declarations must begin with -- |, and not --|.
>> 
>> What might --| mean, if not a comment? It doesn't seem possible to define it
>> as an operator.
> 
> GHCi, at least, allows it.
> 
> Prelude> let (--|) = (+)
> Prelude> 1 --| 2
> 3

I believe the motivating example that persuaded the Language Committee to allow these symbols was
     -->
which is not of course used anywhere in the standard libraries, but is an extremely nice symbol to have available in user code.

Regards,
    Malcolm