prefix minus and infix resolution

Sebastian Fischer sebf at
Tue Jul 13 16:19:22 EDT 2010

On Jul 13, 2010, at 6:38 PM, Christian Maeder wrote:

> I'm asking for support of:

The wording in

     The operator to the left of prefix -, if there is one, is ignored.

is unfortunate. Said operator is not *ignored* in the sense that `a + - 
b` parses as `a - b`. It is just not considered for fixity resolution  
of the mentioned occurrence of prefix -. (It may be considered for  
fixity resolution in a different context.)

I don't have strong opinions on the content of the proposal,  
especially whether I prefer NegationBindsTightly or  
PrefixMinusResolution. (With the above sentence in mind, a funnier -  
and more specific - name would have been NegationBindsRightly :) </ 
aside>). The `- x^2` case is a good argument in favour of your  
proposal, but I'd want to also consider which one is easier to explain  
to the user and easier to implement (but I am lacking the required  

The discussion on "prefix operators" (currently on this list) may shed  
some light on simplicity.


Underestimating the novelty of the future is a time-honored tradition.

More information about the Haskell-prime mailing list