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Re: pattern bugs and comment on intuitive syntax for the


Have you sent these bugs to support at wolfram.com?  That's where bug 
reports should go.

Unless, that is, these are just issues as to how _you_ think Mathematica 
"ought" to behave vs. how it actually behaves.

On 1/2/2011 4:56 AM, Richard Fateman wrote:
>    Guess the results.
>
> x+3 /. x+c___ ->  aha[c]
> x /. x+c___ ->  aha[c]
> x /. x+c___:0 ->  aha[c]
>
> compare to
>
> x+y+3 /. x+y+c___ ->  aha[c]
> x+y  /. x+y+c___ ->  aha[c]
> x+y  /. x+y+c___:0 ->  aha[c]
> x+y+a+b  /. x+y+c___ :>  aha[c]
> x+y+a+b  /. x+y+c___ :>  aha[Plus[c]]
> x+y  /. x+y+c___ :>  aha[Plus[c]]
>
>
>
> I think the requirement for the :0 represents a bug. Maybe the
> need for the Plus[], too. The treatment of NullSequences within
> a Flat operator could be different, leaving an operator around.
>
> ............
>
> Another item. really, syntax.
>
> define
>
> GreaterThan[q_]:= #>q&
> gt2=GreaterThan[2]   (* a function of one argument.
>                           is that argument>  2? *)
>
>
> mm[2, 10] /. mm[q_, s_?GreaterThan[q]] :>  aha[q, s]
>
>    doesn't give aha..
>
>
> mm[2, 10] /. mm[q_, s_?gt2] :>  aha[q, s]
>
> does give aha
>
> this works, though.
> mm[2, 10] /. mm[q_, s_?(GreaterThan[q])] :>  aha[q, s]
>
> I love that intuitive syntax. None of that excess
> parentheses and stuff. (sarcasm)
>
> This error would have been
> much more apparent in Lisp.
>
> happy new year.
>
>
>
>

-- 
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305


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