Bug of syntax-rules pattern matcher

[SaitoAtsushi]

I found a bug in syntax-rules.

For example:

(import (scheme base) (scheme write))

(define-syntax foo
  (syntax-rules ()
    ((_ (p ... . r))
     'r)))

(display (foo (1 2 3 4)))

expected result

()

but, husk report error.

see 4.3.2 in R7RS.

P is of the form (P₁ ... P_k P_e <ellipsis> P_m+1 ... P_n . P_x) where E is a list or improper list of n elements, the first k of which match P₁ through P_k, whose next m-k elements each match P_e, whose remaining n-m elements match P_m+1 through P_n, and whose nth and final cdr matches P_x

n-m is zero in above example case.

[justinethier]

Thanks for the report!

This one will probably take longer than the others to fix, although I need to spend time looking into it in more detail...

[justinethier]

This is fixed on 317-dev, and will be included in the 3.17 release.