R6RS error in syntax parsing

Questions & Answers
1

hello,

i have a code in two versions, Racket and R6RS. The R6RS has a bug i donot understand , even if i can make works the Racket and R6RS with different versions, this version is buggy in R6RS, so i trace all the intermediate variables and they display the same till at end it fails in R6RS with this error:

../infix-with-precedence-to-prefix.sls:372:16: mcar: contract violation
  expected: mpair?
  given: #<syntax ()>

line 372 is :

(map (lambda (x) (recall-infix-parser x operator-precedence creator)) ;; recall-infix-parser
		     terms-local)

i suppose mcar is in map ,but then why map failed on #<syntax ()> ? perheaps is it awaiting '() and not a syntax object. The strange fact is that this sort error is sometimes related to psyntax (Portable syntax)

map is called with this object as argument terms-local:

(#<syntax (2 * 0.3)> . #<syntax ()>)

note: i'm not sure the display of the object is the same as in memory as it contains syntax (sometimes i have bad surprise about that...)

my output is this:

> (define-infix a  (2 * .3))


(define-infix a (2 * 0.3))
$nfx$: #'(expr)=(.#<syntax (2 * 0.3)> . .#<syntax ()>)
!*prec-generic : deep-terms : terms=(.#<syntax (2 * 0.3)> . .#<syntax ()>)
!*prec-generic : deep-terms : WARNING , terms is not a list, perheaps expander is not psyntax (Portable Syntax)
!*prec-generic : deep-terms : terms=(.#<syntax (2 * 0.3)> . .#<syntax ()>)
!*prec-generic : deep-terms : terms-local=(.#<syntax (2 * 0.3)> . .#<syntax ()>)
recall-infix-parser : expr =.#<syntax (2 * 0.3)>
recall-infix-parser : detected syntax,passing from syntax to list (will be used if it is a list)
recall-infix-parser : got a list
!*prec-generic : deep-terms : terms=(.#<syntax 2> .#<syntax *> .#<syntax 0.3>)
!*prec-generic : deep-terms : terms-local=(.#<syntax 2> .#<syntax *> .#<syntax 0.3>)
recall-infix-parser : expr =.#<syntax 2>
recall-infix-parser : detected syntax,passing from syntax to list (will be used if it is a list)
recall-infix-parser : expr not list.
recall-infix-parser : expr =.#<syntax *>
recall-infix-parser : detected syntax,passing from syntax to list (will be used if it is a list)
recall-infix-parser : expr not list.
recall-infix-parser : expr =.#<syntax 0.3>
recall-infix-parser : detected syntax,passing from syntax to list (will be used if it is a list)
recall-infix-parser : expr not list.
. . ../infix-with-precedence-to-prefix.sls:372:16: mcar: contract violation
  expected: mpair?
  given: #<syntax ()>

i can not provide the code in Discourse it is too big ,nor release it on github as it is unstable (but another version that use directly recall-infix-parser and not the classic !*prec-generic works) but that is not the problem, i want to understand... but i can provide the code if someone want to look inside.