SRFI 46 ellipsis renaming not supported

[Alex Shinn]

From SRFI 46:

;;; This example demonstrates the hygienic renaming of the ellipsis
;;; identifiers.

(let-syntax
    ((f (syntax-rules ()
          ((f ?e)
           (let-syntax
               ((g (syntax-rules ::: ()
                     ((g (??x ?e) (??y :::))
                      '((??x) ?e (??y) :::)))))
             (g (1 2) (3 4)))))))
  (f :::))
    ; => ((1) 2 (3) (4)), if hygienic rules of ellipsis identifiers are
    ;      correctly implemented, not ((1) (2) (3) (4))

[Takashi Kato]

Thank you for the report!

Assume the script uses (scheme base) not (rnrs). The result seemed fine to me, but I've got an error during expansion when I executed without -r7 option. This is because ::: is read as a keyword not a symbol.

Other error also occurred on REPL, this is because REPL automatically imports (rnrs) but (scheme base). This needs to be fixed.

[Takashi Kato]

Importing (scheme base) on R7RS mode REPL. (Fixes #198)

→ <<cset c3011b0fdb63>>

[Alex Shinn]

Thanks! However I applied the patch in c3011b0fdb63 to 0.7.8 and still get an error:

$ sash -r7
sash[r7rs]> (let-syntax
    ((f (syntax-rules ()
          ((f ?e)
           (let-syntax
               ((g (syntax-rules ooo ()
                     ((g (??x ?e) (??y ooo))
                      '((??x) ?e (??y) ooo)))))
             (g (1 2) (3 4)))))))
    (f ooo))
Unhandled exception
  Condition components:
  1. &compile
    program: (let-syntax ((f (syntax-rules () ((f ?e) (let-syntax ((g (sy
    source: #f
  2. &compile
    program: (syntax-rules ooo () ((g (??x ooo) (??y ooo)) '((??x) ooo (?
    source: #f
  3. &syntax
    subform: #f
    form: (syntax-rules ooo () ((g (??x ooo) (??y ooo)) '((??x) ooo (??y) ooo)))
  4. &who #<identifier syntax-rules#user (#:id.2 #f #f . #f) (0x107b077c0):1>
  5. &message invalid syntax

stack trace:
  [1] report-error
  [2] #f
    src: ((current-exception-printer) c (current-error-port
    "/usr/local/share/sagittarius/0.7.8/lib/sagittarius/interactive.scm":133
  [3] default-exception-handler
  [4] raise
  [5] default-exception-handler
  [6] raise
  [7] default-exception-handler
  [8] raise
  [9] dynamic-wind
  [10] pass1
  [11] pass1
  [12] with-error-handler
  [13] pass1/eval-macro-rhs
  [14] pass1/let-syntax
  [15] pass1/let-syntax
  [16] with-error-handler
  [17] dynamic-wind
  [18] eval
  [19] #f
    src: ((current-evaluator) form interactive-environment)
    "/usr/local/share/sagittarius/0.7.8/lib/sagittarius/interactive.scm":145
  [20] with-error-handler
      ... (more stack dump truncated)

[Takashi Kato]

The fix contains the change of precompiled files, so If you applied patch to released tar ball, then you need to re-generate them with the following command (must be in the source directory):

$ ./dist.sh precomp

[Alex Shinn]

Thanks, that makes progress but it still has problems in libraries:

$ sash -r7 -S.sld -L/path/to/chibi/lib -I'(chibi show base)'
Unhandled exception
  Condition components:
  1. &compile
    program: (import |(chibi show base)|)
    source: #f
  2. &compile
    program: (define-library (chibi show base) (export show fn fn-fork wi
    source: "/Users/foof/src/chibi-scheme/lib/chibi/show/base.sld":2
  3. &compile
    program: (syntax-rules ::: () ((fn ("step") (params :::) ((p param) .
    source: syntax-rules:(:: () ((f! (step) (params ::) ((p param) . rest) . body) (f! (step) (params :: (p param)) rest . body)) ((f! (step) (params ::) ((param) . rest) . body) (f! (step) (params :: (param param)) rest . body)) ((f! (step) (params ::) (param . rest) . body) (f! (step) (params :: (param param)) rest . body)) ((f! (step) ((p param) ::) () . body) (lambda (st) (let ((p (ask st 'param)) ::) ((let () . body) st)))) ((f! params . body) (f! (step) () params . body)))
  4. &assertion
  5. &who car
  6. &message "pair" required, but got ()
  7. &irritants ()
  8. &stack-trace

It looks like ::: is still being interpreted as a keyword. Replacing it with ooo works fine, so for now I'll use that as a workaround.

[Takashi Kato]

If the ::: is defined in other library, then it would raise an error since default reader reads ::: as a keyword.

NOTE: .sld is supported by default and R7RS reader is used to read files whose suffix are .sld. So removing -S.sld options would help.