[Axiom-developer] Re: [Axiom-mail] A pattern matching question

[Martin Rubey]

Dear Themos, Alasdair,

trying to debug the freeOf? pattern, I discovered that Themos' pattern suffers
from the same problem:

tt:=operator 'tt; ttrules := rule tt(n/(n^a+(X | integer?(a) and (n-1)^a = n^a 
+X))) == 1/t^a

(100) -> ttrules tt(n/(n^6+anything))

           1
   (100)  --
           6
          t
                                                     Type: Expression Integer

The problem seems to be that the syntactic sugar for the suchThat operation "|"
only works if we have a function of a single variable.  Of course, calling
suchThat without sugar, axiom does the right thing:

(101) -> ttrules := suchThat(rule tt(n/(n^a+X)) == 1/t^a, [a, X], l +-> 
integer? first
 l and (n-1)^(first l) = n^(first l) + second l)

                n        1
   (101)  tt(------) == --
              a          a
             n  + X     t
                        Type: RewriteRule(Integer,Integer,Expression Integer)
(102) -> ttrules tt(n/(n^6+anything))

                   n
   (102)  tt(-------------)
              6
             n  + anything
                                                     Type: Expression Integer
(103) -> ttrules tt(n/((n-1)^6))

           1
   (103)  --
           6
          t
                                                     Type: Expression Integer