On Jul 13, 2010, at 6:38 PM, Christian Maeder wrote:
I'm asking for support of:
http://hackage.haskell.org/trac/haskell-prime/wiki/PrefixMinusResolution
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 :) ). 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 knowledge). The discussion on "prefix operators" (currently on this list) may shed some light on simplicity. Sebastian -- Underestimating the novelty of the future is a time-honored tradition. (D.G.)