Comment Syntax

Thomas Davie tatd2 at
Mon Jan 30 07:17:44 EST 2006

I would like to suggest a different change to single line comment  
syntax to do two things.  First, address an inconsistency with multi  
line comments, and secondly remove one of the main sources of  
confusion for beginners.

My proposal is to make any text beginning '--' a comment (rather than  
requiring a space after the two dashes.  I appreciate that the  
argument against this is that various operators that look like this  
are useful (e.g. -->).  However I think that any benefit gained by  
operators like this is lost in confusion.

In order to back up my suggestion, I'd like to point out, that this  
is indeed already how it is done for block comments.  i.e. we do not  
expect {-> to be an operator, we expect it to be the beginning of a  

Secondly, from my limited experience helping to teach Haskell, the  
comment syntax is a primary source of confusion for beginners.   
Beginners inevitably forget (or don't know) to add the space, and  
will receive confusing errors about undefined symbols, or type  
mismatches.  This is made yet more confusing by the fact that the  
compiler appears to be pointing at an error in a comment.


Tom Davie

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