From 64a1ddcda96748b28727e0a3334d46e91c51aea5 Mon Sep 17 00:00:00 2001
From: Robby Findler <robby@racket-lang.org>
Date: Thu, 29 Jul 2010 06:57:39 -0500
Subject: [PATCH] adjusted the syntax for ->i so that #:rest is not ambiguous
 anymore (added extra parens, deviating from ->d a little bit) and updated the
 test suite

---
 .../racket/contract/private/arr-i-parse.rkt   | 210 +++++++++++++++---
 collects/racket/contract/private/arr-i.rkt    |  30 +--
 collects/racket/contract/scratch.rkt          |  11 +
 .../scribblings/reference/contracts.scrbl     |   2 +-
 collects/tests/racket/contract-test.rktl      | 144 ++++++------
 5 files changed, 274 insertions(+), 123 deletions(-)

diff --git a/collects/racket/contract/private/arr-i-parse.rkt b/collects/racket/contract/private/arr-i-parse.rkt
index 7d785fb569..68ee6df7af 100644
--- a/collects/racket/contract/private/arr-i-parse.rkt
+++ b/collects/racket/contract/private/arr-i-parse.rkt
@@ -1,4 +1,14 @@
 #lang racket/base
+(require syntax/private/boundmap
+         (for-template racket/base
+                       "guts.rkt"))
+;; the private version of the library 
+;; (the one without contracts)
+;; has these old, wrong names in it.
+(define make-free-identifier-mapping make-module-identifier-mapping)
+(define free-identifier-mapping-get module-identifier-mapping-get)
+(define free-identifier-mapping-put! module-identifier-mapping-put!)
+
 #|
 
 The ->i contract first parses its input into an istx struct 
@@ -7,47 +17,162 @@ and then operates on it to generate the expanded form
 |#
 
 ;; doms : (listof arg?)
-;; pre  : (or/c stx[expr] #f)
-;; rngs : (listof res?)
 ;; rest : (or/c #f rst?)
+;; pre  : (or/c stx[expr] #f)
+;; rngs : (or/c #f (listof res?))
 ;; post : (or/c stx[expr] #f)
-(define-struct istx (doms pre rngs rest post))
-
-;; var  : identifier?
-;; vars : (or/c #f (listof identifier?))
-;; ctc  : syntax[expr]
-(define-struct res (var vars ctc))
+(struct istx (args rst pre ress post))
 
 ;; kwd  : (or/c #f syntax[kwd])
 ;; var  : identifier?
 ;; vars : (or/c #f (listof identifier?))
 ;; optional? : boolean?
 ;; ctc  : syntax[expr]
-(define-struct arg (kwd var vars optional? ctc))
+(struct arg (kwd var vars optional? ctc))
 
 ;; var  : identifier?
 ;; vars : (or/c #f (listof identifier?))
 ;; ctc  : syntax[expr]
-(define-struct rst (var vars ctc))
+(struct res (var vars ctc))
+
+;; var  : identifier?
+;; vars : (or/c #f (listof identifier?))
+;; ctc  : syntax[expr]
+(struct rst (var vars ctc))
 
 (define (parse-->i stx)
-  (let-values ([(raw-mandatory-doms raw-optional-doms id/rest-id pre-cond range post-cond)
+  (let-values ([(raw-mandatory-doms raw-optional-doms
+                 id/rest-id pre-cond range post-cond)
                 (pull-out-pieces stx)])
-    (make-istx (append (map parse-dom raw-mandatory-doms)
-                       (map parse-dom raw-optional-doms))
-               pre-cond
-               range
-               rest
-               post)))
+    (let ([candidate
+           (istx (append (parse-doms stx #f raw-mandatory-doms)
+                         (parse-doms stx #t raw-optional-doms))
+                 id/rest-id
+                 pre-cond
+                 (parse-range stx range)
+                 post-cond)])
+      (ensure-wf-names stx candidate)
+      ;(ensure-no-cycles stx candidate)
+      candidate)))
+
+(define (ensure-wf-names stx istx)
+  (let ([km (make-hash)]
+        [nm (make-free-identifier-mapping)])
+    
+    (define (no-var-dups var)
+      (cond
+        [(free-identifier-mapping-get nm var (λ () #f))
+         =>
+         (λ (other)
+           (raise-syntax-error #f "duplicate dependent variables"
+                               stx other (list var)))]
+        [else
+         (free-identifier-mapping-put! nm var var)]))
+    
+    (define (no-kwd-dups kwd-stx)
+      (let ([kwd (syntax-e kwd-stx)])
+        (cond
+          [(hash-ref km kwd #f)
+           =>
+           (λ (that)
+             (raise-syntax-error #f "duplicate keywords" 
+                                 stx that (list kwd-stx)))]
+          [else
+           (hash-set! km kwd kwd-stx)])))
+    
+    (for ([dom (in-list (istx-args istx))])
+      (when (arg-kwd dom)
+        (no-kwd-dups (arg-kwd dom)))
+      (no-var-dups (arg-var dom)))
+    
+    (when (istx-ress istx)
+      (let ([any-_? #f]
+            [all-_? #t])
+        (for ([rng (in-list (istx-ress istx))])
+          (cond
+            [(free-identifier=? #'_ (res-var rng))
+             (set! any-_? #t)]
+            [else 
+             (set! all-_? #f)
+             (no-var-dups (res-var rng))]))
+        (when any-_?
+          (unless all-_?
+            (raise-syntax-error #f "either all of the dependent range variables must be _ or none of them"
+                                stx (map res-var (istx-ress istx)))))))
+    
+    (when (istx-rst istx)
+      (no-var-dups (rst-var (istx-rst istx))))))
+    
+(define (parse-doms stx optional? doms)
+  (let loop ([doms doms])
+    (syntax-case doms ()
+      [(kwd [id ctc-expr] . rest)
+       (keyword? (syntax-e #'kwd))
+       (begin
+         (check-id stx #'id)
+         (cons (arg #'kwd #'id #f optional? #'ctc-expr)
+               (loop #'rest)))]
+      [(kwd [id (id2 ...) ctc-expr] . rest)
+       (keyword? (syntax-e #'kwd))
+       (begin
+         (check-id stx #'id)
+         (for-each (λ (x) (check-id stx x)) (syntax->list #'(id2 ...)))
+         (cons (arg #'kwd #'id (syntax->list #'(id2 ...)) optional? #'ctc-expr)
+               (loop #'rest)))]
+      [([id ctc-expr] . rest)
+       (begin
+         (check-id stx #'id)
+         (cons (arg #f #'id #f optional? #'ctc-expr)
+               (loop #'rest)))]
+      [([id (id2 ...) ctc-expr] . rest)
+       (begin
+         (check-id stx #'id)
+         (for-each (λ (x) (check-id stx x)) (syntax->list #'(id2 ...)))
+         (cons (arg #f #'id (syntax->list #'(id2 ...)) optional? #'ctc-expr)
+               (loop #'rest)))]
+      [() '()]
+      [(a . rest)
+       (raise-syntax-error #f "expected an argument specification" stx #'a)])))
+
+(define (parse-range stx range)
+  (syntax-case range (any values) #;(λ (x y) (eq? (syntax-e x) (syntax-e y)))
+    [(values ctc-pr ...)
+     (map (λ (x) (syntax-case x ()
+                   [[id ctc] 
+                    (begin
+                      (check-id stx #'id)
+                      (res #'id #f #'ctc))]
+                   [[id (id2 ...) ctc]
+                    (begin
+                      (check-id stx #'id)
+                      (for-each (λ (x) (check-id stx x)) (syntax->list #'(id2 ...)))
+                      (res #'id (syntax->list #'(id2 ...)) #'ctc))]
+                   [x (raise-syntax-error #f "expected binding pair" stx #'x)]))
+          (syntax->list #'(ctc-pr ...)))]
+    [any #f]
+    [[id ctc]
+     (begin
+       (check-id stx #'id)
+       (list (res #'id #f #'ctc)))]
+    [[id (id2 ...) ctc] 
+     (begin
+       (check-id stx #'id)
+       (for-each (λ (x) (check-id stx x)) (syntax->list #'(id2 ...)))
+       (list (res #'id (syntax->list #'(id2 ...)) #'ctc)))]
+    [x (raise-syntax-error #f "expected the range portion" stx #'x)]))
+
+(define (check-id stx id)
+  (unless (identifier? id)
+    (raise-syntax-error #f "expected an identifier" stx id)))
 
 ;; pull-out-pieces : stx -> (values raw-mandatory-doms raw-optional-doms id/rest-id pre-cond range post-cond) 
 (define (pull-out-pieces stx)
   (let*-values ([(raw-mandatory-doms leftover) 
                  (syntax-case stx ()
-                   [((raw-mandatory-doms ...) . leftover)
+                   [(_ (raw-mandatory-doms ...) . leftover)
                     (values (syntax->list #'(raw-mandatory-doms ...)) 
                             #'leftover)]
-                   [(a . leftover)
+                   [(_ a . leftover)
                     (raise-syntax-error #f "expected a sequence of mandatory domain elements" stx #'a)]
                    [_
                     (raise-syntax-error #f "expected a sequence of mandatory domain elements" stx)])]
@@ -65,21 +190,30 @@ and then operates on it to generate the expanded form
                    [_ (values '() leftover)])]
                 [(id/rest-id leftover) 
                  (syntax-case leftover ()
-                   [(#:rest id rest-expr . leftover)
-                    (and (identifier? #'id)
-                         (not (keyword? (syntax-e #'rest-expr))))
-                    (values #'(id rest-expr) #'leftover)]
-                   [(#:rest id (id2 ...) rest-expr . leftover)
-                    (and (identifier? #'id)
-                         (andmap identifier? (syntax->list #'(id2 ...)))
-                         (not (keyword? (syntax-e #'rest-expr))))
-                    (values #'(id rest-expr) #'leftover)]
-                   [(#:rest id rest-expr . leftover)
+                   [(#:rest [id rest-expr] . leftover)
                     (begin
-                      (unless (identifier? #'id)
-                        (raise-syntax-error #f "expected an identifier" stx #'id))
-                      (when (keyword? (syntax-e #'rest-expr))
-                        (raise-syntax-error #f "expected an expression, not a keyword" stx #'rest-expr)))]
+                      (check-id stx #'id)
+                      (values (rst #'id #f #'rest-expr)
+                              #'leftover))]
+                   [(#:rest [id (id2 ...) rest-expr] . leftover)
+                    (begin
+                      (check-id stx #'id)
+                      (for-each (λ (x) (check-id stx x))
+                                (syntax->list #'(id2 ...)))
+                      (values (rst #'id 
+                                   (syntax->list #'(id2 ...))
+                                   #'rest-expr)
+                              #'leftover))]
+                   [(#:rest other . leftover)
+                    (raise-syntax-error #f "expected an id+ctc"
+                                        stx
+                                        #'other)]
+                   [(x)
+                    (eq? (syntax-e #'x) '#:rest)
+                    (raise-syntax-error 
+                     #f 
+                     "expected something to follow #:rest"
+                     stx #'x)]
                    [_ (values #f leftover)])]
                 [(pre-cond leftover)
                  (syntax-case leftover ()
@@ -89,8 +223,8 @@ and then operates on it to generate the expanded form
                 [(range leftover) 
                  (syntax-case leftover ()
                    [(range . leftover) (values #'range #'leftover)]
-                   [_
-                    (raise-syntax-error #f "expected a range expression, but found nothing" stx)])]
+                   [()
+                    (raise-syntax-error #f "expected a range expression, but found nothing" stx leftover)])]
                 [(post-cond leftover) 
                  (syntax-case leftover ()
                    [(#:post-cond post-cond . leftover)
@@ -106,6 +240,12 @@ and then operates on it to generate the expanded form
       [_ 
        (raise-syntax-error #f "bad syntax" stx)])))
 
+;(define (ensure-no-cycles istx)
+;  (let (;; cm : id -o> {'pending, 'no-cycle}
+;        [cm (make-free-identifier-map)])
+;    (for ([dom (in-list (istx-args istx))])
+;      (let loop ([id (
+
 (provide
  parse-->i
  (struct-out istx)
diff --git a/collects/racket/contract/private/arr-i.rkt b/collects/racket/contract/private/arr-i.rkt
index 3957622a1d..2978bf34de 100644
--- a/collects/racket/contract/private/arr-i.rkt
+++ b/collects/racket/contract/private/arr-i.rkt
@@ -3,13 +3,15 @@
 (require "guts.rkt"
          "arrow.rkt"
          "opt.rkt"
-         racket/stxparam)
-(require (for-syntax racket/base)
-         (for-syntax "opt-guts.rkt")
-         (for-syntax "helpers.rkt")
-         (for-syntax syntax/stx)
-         (for-syntax syntax/name)
-         (for-syntax "arr-util.rkt"))
+         racket/stxparam
+         
+         (for-syntax racket/base
+                     syntax/stx
+                     syntax/name
+                     "arr-i-parse.rkt"
+                     "opt-guts.rkt"
+                     "helpers.rkt"
+                     "arr-util.rkt"))
 
 (provide ->i)
 
@@ -34,21 +36,17 @@
                    [_ (values '() leftover)])]
                 [(id/rest-id leftover) 
                  (syntax-case leftover ()
-                   [(#:rest id rest-expr . leftover)
+                   [(#:rest [id rest-expr] . leftover)
                     (and (identifier? #'id)
                          (not (keyword? (syntax-e #'rest-expr))))
                     (values #'(id rest-expr) #'leftover)]
-                   [(#:rest id (id2 ...) rest-expr . leftover)
+                   [(#:rest [id (id2 ...) rest-expr] . leftover)
                     (and (identifier? #'id)
                          (andmap identifier? (syntax->list #'(id2 ...)))
                          (not (keyword? (syntax-e #'rest-expr))))
                     (values #'(id rest-expr) #'leftover)]
-                   [(#:rest id rest-expr . leftover)
-                    (begin
-                      (unless (identifier? #'id)
-                        (raise-syntax-error #f "expected an identifier" stx #'id))
-                      (when (keyword? (syntax-e #'rest-expr))
-                        (raise-syntax-error #f "expected an expression, not a keyword" stx #'rest-expr)))]
+                   [(#:rest something . leftover)
+                    (raise-syntax-error #f "expected id+ctc" stx #'something)]
                    [_ (values #f leftover)])]
                 [(pre-cond leftover)
                  (syntax-case leftover ()
@@ -145,6 +143,8 @@
     (values pre post)))
 
 (define-syntax (->i stx)
+  (parse-->i stx)
+  (printf "finished ->i parsing\n")
   (syntax-case stx ()
     [(_ (raw-mandatory-doms ...)
         .
diff --git a/collects/racket/contract/scratch.rkt b/collects/racket/contract/scratch.rkt
index 4467506496..8ddbedba35 100644
--- a/collects/racket/contract/scratch.rkt
+++ b/collects/racket/contract/scratch.rkt
@@ -1,6 +1,12 @@
 #lang racket/base
 (require racket/contract)
 
+(let ([c integer?])
+  (->i ((arg any/c)) () (values (_ (arg) c) (x (arg) c) (_ (arg) c))))
+; => all or none _s
+
+
+#;
 (->i (#:kwd1 [x number?]
       #:kwd2 [y number?])
      #:rest [x any/c]
@@ -56,4 +62,9 @@ test cases:
      [x number?])
 ;=> duplicate identifier 'x'
 
+(let ([c integer?])
+  (->i ((arg any/c)) () (values (_ (arg) c) (x (arg) c) (_ (arg) c))))
+; => all or none _s
+
+
 |#
diff --git a/collects/scribblings/reference/contracts.scrbl b/collects/scribblings/reference/contracts.scrbl
index b4afc8589f..9d8f1c901c 100644
--- a/collects/scribblings/reference/contracts.scrbl
+++ b/collects/scribblings/reference/contracts.scrbl
@@ -516,7 +516,7 @@ symbols, and that return a symbol.
                           (code:line keyword id+ctc)]
  [optional-dependent-dom id+ctc
                          (code:line keyword id+ctc)]
- [dependent-rest (code:line) (code:line #:rest id rest-expr)]
+ [dependent-rest (code:line) (code:line #:rest id+ctc)]
  [pre-condition (code:line) (code:line #:pre-cond boolean-expr)]
  [dependent-range any
                   id+ctc
diff --git a/collects/tests/racket/contract-test.rktl b/collects/tests/racket/contract-test.rktl
index 1935a7ac8f..64843c38d3 100644
--- a/collects/tests/racket/contract-test.rktl
+++ b/collects/tests/racket/contract-test.rktl
@@ -185,8 +185,8 @@
   (test/no-error '(->i ([x integer?]) ([y integer?]) any))
   (test/no-error '(->i ([x integer?]) ([y integer?]) (values [a number?] [b boolean?])))
   (test/no-error '(->i ([x integer?] #:z [z integer?]) ([y integer?] #:w [w integer?]) (range boolean?)))
-  (test/no-error '(->i ([x integer?] #:z [z integer?]) ([y integer?] #:w [w integer?]) #:rest rest any/c (range boolean?)))
-  (test/no-error '(->i ([x integer?] #:z [z integer?]) #:rest rest any/c (range boolean?)))
+  (test/no-error '(->i ([x integer?] #:z [z integer?]) ([y integer?] #:w [w integer?]) #:rest [rest any/c] (range boolean?)))
+  (test/no-error '(->i ([x integer?] #:z [z integer?]) #:rest [rest any/c] (range boolean?)))
 
   (test/no-error '(unconstrained-domain-> number?))
   (test/no-error '(unconstrained-domain-> (flat-contract number?)))
@@ -1803,51 +1803,51 @@
 
   (test/spec-passed
    '->i11
-   '((contract (->i () () #:rest rest any/c [r number?]) (lambda x 1) 'pos 'neg)))
+   '((contract (->i () () #:rest [rest any/c] [r number?]) (lambda x 1) 'pos 'neg)))
   
   (test/spec-passed
    '->i12
-   '((contract (->i ([x number?]) () #:rest rest any/c [r number?]) (lambda (x . y) (+ x 1)) 'pos 'neg) 1))
+   '((contract (->i ([x number?]) () #:rest [rest any/c] [r number?]) (lambda (x . y) (+ x 1)) 'pos 'neg) 1))
 
   (test/pos-blame
    '->i13
-   '((contract (->i () () #:rest rest any/c [r number?]) 1 'pos 'neg)))
+   '((contract (->i () () #:rest [rest any/c] [r number?]) 1 'pos 'neg)))
   
   (test/pos-blame
    '->i14
-   '((contract (->i () () #:rest rest any/c [r number?]) (lambda (x) x) 'pos 'neg)))
+   '((contract (->i () () #:rest [rest any/c] [r number?]) (lambda (x) x) 'pos 'neg)))
   
   (test/neg-blame
    '->i15
-   '((contract (->i ([x number?]) () #:rest rest any/c any) (lambda (x . y) (+ x 1)) 'pos 'neg) #f))
+   '((contract (->i ([x number?]) () #:rest [rest any/c] any) (lambda (x . y) (+ x 1)) 'pos 'neg) #f))
   
   (test/pos-blame
    '->i16
-   '((contract (->i ([x number?]) () #:rest rest any/c [r (x) (<=/c x)]) (lambda (x . y) (+ x 1)) 'pos 'neg) 1))
+   '((contract (->i ([x number?]) () #:rest [rest any/c] [r (x) (<=/c x)]) (lambda (x . y) (+ x 1)) 'pos 'neg) 1))
   
   (test/spec-passed
    '->i17
-   '((contract (->i ([x number?] [y (x) (<=/c x)]) () #:rest rest any/c [r (x) (<=/c x)]) (lambda (x y . z) (- x 1)) 'pos 'neg) 1 0))
+   '((contract (->i ([x number?] [y (x) (<=/c x)]) () #:rest [rest any/c] [r (x) (<=/c x)]) (lambda (x y . z) (- x 1)) 'pos 'neg) 1 0))
   
   (test/neg-blame
    '->i18
-   '((contract (->i ([x number?] [y (x) (<=/c x)]) () #:rest rest any/c [r (x) (<=/c x)]) (lambda (x y . z) (+ x 1)) 'pos 'neg) 1 2))
+   '((contract (->i ([x number?] [y (x) (<=/c x)]) () #:rest [rest any/c] [r (x) (<=/c x)]) (lambda (x y . z) (+ x 1)) 'pos 'neg) 1 2))
   
   (test/spec-passed
    '->i19
-   '((contract (->i ([y (x) (<=/c x)] [x number?]) () #:rest rest any/c [r (x) (<=/c x)]) (lambda (y x . z) (- x 1)) 'pos 'neg) 1 2))
+   '((contract (->i ([y (x) (<=/c x)] [x number?]) () #:rest [rest any/c] [r (x) (<=/c x)]) (lambda (y x . z) (- x 1)) 'pos 'neg) 1 2))
   
   (test/neg-blame
    '->i20
-   '((contract (->i ([y (x) (<=/c x)] [x number?]) () #:rest rest any/c [r (x) (<=/c x)]) (lambda (y x . z) (+ x 1)) 'pos 'neg) 1 0))
+   '((contract (->i ([y (x) (<=/c x)] [x number?]) () #:rest [rest any/c] [r (x) (<=/c x)]) (lambda (y x . z) (+ x 1)) 'pos 'neg) 1 0))
 
   (test/spec-passed
    '->i21
-   '((contract (->i () () #:rest rst (listof number?) [r any/c]) (lambda w 1) 'pos 'neg) 1))
+   '((contract (->i () () #:rest [rst (listof number?)] [r any/c]) (lambda w 1) 'pos 'neg) 1))
   
   (test/neg-blame
    '->i22
-   '((contract (->i () () #:rest rst (listof number?) [r any/c]) (lambda w 1) 'pos 'neg) #f))
+   '((contract (->i () () #:rest [rst (listof number?)] [r any/c]) (lambda w 1) 'pos 'neg) #f))
   
   (test/spec-passed
    '->i-any1
@@ -1887,47 +1887,47 @@
   
   (test/spec-passed
    '->i-any10
-   '((contract (->i () () #:rest rest any/c any) (lambda x 1) 'pos 'neg)))
+   '((contract (->i () () #:rest [rest any/c] any) (lambda x 1) 'pos 'neg)))
   
   (test/spec-passed
    '->i-any11
-   '((contract (->i ([x number?]) () #:rest rest any/c any) (lambda (x . y) (+ x 1)) 'pos 'neg) 1))
+   '((contract (->i ([x number?]) () #:rest [rest any/c] any) (lambda (x . y) (+ x 1)) 'pos 'neg) 1))
 
   (test/pos-blame
    '->i-any12
-   '((contract (->i () () #:rest rest any/c any) 1 'pos 'neg)))
+   '((contract (->i () () #:rest [rest any/c] any) 1 'pos 'neg)))
   
   (test/pos-blame
    '->i-any13
-   '((contract (->i () () #:rest rest any/c any) (lambda (x) x) 'pos 'neg)))
+   '((contract (->i () () #:rest [rest any/c] any) (lambda (x) x) 'pos 'neg)))
   
   (test/neg-blame
    '->i-any14
-   '((contract (->i ([x number?]) () #:rest rest any/c any) (lambda (x . y) (+ x 1)) 'pos 'neg) #f))
+   '((contract (->i ([x number?]) () #:rest [rest any/c] any) (lambda (x . y) (+ x 1)) 'pos 'neg) #f))
   
   (test/spec-passed
    '->i-any15
-   '((contract (->i ([x number?] [y (x) (<=/c x)]) () #:rest rest any/c any) (lambda (x y . z) (- x 1)) 'pos 'neg) 1 0))
+   '((contract (->i ([x number?] [y (x) (<=/c x)]) () #:rest [rest any/c] any) (lambda (x y . z) (- x 1)) 'pos 'neg) 1 0))
   
   (test/neg-blame
    '->i-any16
-   '((contract (->i ([x number?] [y (x) (<=/c x)]) () #:rest rest any/c any) (lambda (x y . z) (+ x 1)) 'pos 'neg) 1 2))
+   '((contract (->i ([x number?] [y (x) (<=/c x)]) () #:rest [rest any/c] any) (lambda (x y . z) (+ x 1)) 'pos 'neg) 1 2))
   
   (test/spec-passed
    '->i-any17
-   '((contract (->i ([y (x) (<=/c x)] [x number?]) () #:rest rest any/c any) (lambda (y x . z) (- x 1)) 'pos 'neg) 1 2))
+   '((contract (->i ([y (x) (<=/c x)] [x number?]) () #:rest [rest any/c] any) (lambda (y x . z) (- x 1)) 'pos 'neg) 1 2))
   
   (test/neg-blame
    '->i-any18
-   '((contract (->i ([y (x) (<=/c x)] [x number?]) () #:rest rest any/c any) (lambda (y x . z) (+ x 1)) 'pos 'neg) 1 0))
+   '((contract (->i ([y (x) (<=/c x)] [x number?]) () #:rest [rest any/c] any) (lambda (y x . z) (+ x 1)) 'pos 'neg) 1 0))
 
   (test/spec-passed
    '->i-any19
-   '((contract (->i () () #:rest rst (listof number?) any) (lambda w 1) 'pos 'neg) 1))
+   '((contract (->i () () #:rest [rst (listof number?)] any) (lambda w 1) 'pos 'neg) 1))
   
   (test/neg-blame
    '->i-any20
-   '((contract (->i () () #:rest rst (listof number?) any) (lambda w 1) 'pos 'neg) #f))
+   '((contract (->i () () #:rest [rst (listof number?)] any) (lambda w 1) 'pos 'neg) #f))
 
   (test/spec-passed
    '->i-values1
@@ -1988,11 +1988,11 @@
   
   (test/spec-passed
    '->i-values11
-   '((contract (->i () () #:rest rest any/c (values [z boolean?] [w number?])) (lambda x (values #f 1)) 'pos 'neg)))
+   '((contract (->i () () #:rest [rest any/c] (values [z boolean?] [w number?])) (lambda x (values #f 1)) 'pos 'neg)))
   
   (test/spec-passed
    '->i-values12
-   '((contract (->i ([x number?]) () #:rest rest any/c (values [z boolean?] [w number?]))
+   '((contract (->i ([x number?]) () #:rest [rest any/c] (values [z boolean?] [w number?]))
                (lambda (x . y) (values #f (+ x 1)))
                'pos 
                'neg)
@@ -2000,55 +2000,55 @@
 
   (test/pos-blame
    '->i-values13
-   '((contract (->i () () #:rest rest any/c (values [z boolean?] [w number?])) 1 'pos 'neg)))
+   '((contract (->i () () #:rest [rest any/c] (values [z boolean?] [w number?])) 1 'pos 'neg)))
   
   (test/pos-blame
    '->i-values14
-   '((contract (->i () () #:rest rest any/c (values [z boolean?] [w number?])) (lambda (x) x) 'pos 'neg)))
+   '((contract (->i () () #:rest [rest any/c] (values [z boolean?] [w number?])) (lambda (x) x) 'pos 'neg)))
   
   (test/neg-blame
    '->i-values15
-   '((contract (->i ([x number?]) () #:rest rest any/c  (values [z boolean?] [w (x) (<=/c x)]))
+   '((contract (->i ([x number?]) () #:rest [rest any/c]  (values [z boolean?] [w (x) (<=/c x)]))
                (lambda (x . y) (+ x 1)) 'pos 'neg)
      #f))
   
   (test/pos-blame
    '->i-values16
-   '((contract (->i ([x number?]) () #:rest rest any/c (values [z boolean?] [w (x) (<=/c x)]))
+   '((contract (->i ([x number?]) () #:rest [rest any/c] (values [z boolean?] [w (x) (<=/c x)]))
                (lambda (x . y) (values #f (+ x 1))) 'pos 'neg) 
      1))
   
   (test/spec-passed
    '->i-values17
-   '((contract (->i ([x number?] [y (x) (<=/c x)]) () #:rest rest any/c (values [z boolean?] [w (x) (<=/c x)]))
+   '((contract (->i ([x number?] [y (x) (<=/c x)]) () #:rest [rest any/c] (values [z boolean?] [w (x) (<=/c x)]))
                (lambda (x y . z) (values #f (- x 1))) 'pos 'neg) 
      1 0))
   
   (test/neg-blame
    '->i-values18
-   '((contract (->i ([x number?] [y (x) (<=/c x)]) () #:rest rest any/c (values [z boolean?] [w (x) (<=/c x)]))
+   '((contract (->i ([x number?] [y (x) (<=/c x)]) () #:rest [rest any/c] (values [z boolean?] [w (x) (<=/c x)]))
                (lambda (x y . z) (values #f (+ x 1))) 'pos 'neg) 
      1 2))
   
   (test/spec-passed
    '->i-values19
-   '((contract (->i ([y (x) (<=/c x)] [x number?]) () #:rest rest any/c  (values [z boolean?] [w (x) (<=/c x)]))
+   '((contract (->i ([y (x) (<=/c x)] [x number?]) () #:rest [rest any/c]  (values [z boolean?] [w (x) (<=/c x)]))
                (lambda (y x . z) (values #f (- x 1))) 'pos 'neg)
      1 2))
   
   (test/neg-blame
    '->i-values20
-   '((contract (->i ([y (x) (<=/c x)] [x number?]) () #:rest rest any/c  (values [z boolean?] [w (x) (<=/c x)]))
+   '((contract (->i ([y (x) (<=/c x)] [x number?]) () #:rest [rest any/c]  (values [z boolean?] [w (x) (<=/c x)]))
                (lambda (y x . z) (values #f (+ x 1))) 'pos 'neg) 
      1 0))
 
   (test/spec-passed
    '->i-values21
-   '((contract (->i () () #:rest rst (listof number?) (values [z boolean?] [w any/c])) (lambda w (values #f 1)) 'pos 'neg) 1))
+   '((contract (->i () () #:rest [rst (listof number?)] (values [z boolean?] [w any/c])) (lambda w (values #f 1)) 'pos 'neg) 1))
   
   (test/neg-blame
    '->i-values22
-   '((contract (->i () () #:rest rst (listof number?) (values [z boolean?] [w any/c])) (lambda w (values #f 1)) 'pos 'neg) #f))
+   '((contract (->i () () #:rest [rst (listof number?)] (values [z boolean?] [w any/c])) (lambda w (values #f 1)) 'pos 'neg) #f))
 
   (test/spec-passed
    '->i-values23
@@ -2101,7 +2101,7 @@
 
   (test/spec-passed/result
    '->i26
-   '((contract (->i ((i number?) (j (i) (and/c number? (>=/c i)))) () #:rest rest-args any/c [r number?])
+   '((contract (->i ((i number?) (j (i) (and/c number? (>=/c i)))) () #:rest [rest-args any/c] [r number?])
                (λ (i j . z) 1)
                'pos
                'neg)
@@ -2111,7 +2111,7 @@
 
   (test/spec-passed/result
    '->i27
-   '((contract (->i ((i number?) (j (i) (and/c number? (>=/c i)))) () #:rest rest-args any/c any)
+   '((contract (->i ((i number?) (j (i) (and/c number? (>=/c i)))) () #:rest [rest-args any/c] any)
                (λ (i j . z) 1)
                'pos
                'neg)
@@ -2123,7 +2123,7 @@
    '->i28
    '(call-with-values
      (λ ()
-       ((contract (->i ((i number?) (j (i) (and/c number? (>=/c i)))) () #:rest rest-args any/c (values [x number?] [y number?]))
+       ((contract (->i ((i number?) (j (i) (and/c number? (>=/c i)))) () #:rest [rest-args any/c] (values [x number?] [y number?]))
                   (λ (i j . z) (values 1 2))
                   'pos
                   'neg)
@@ -2134,7 +2134,7 @@
   
   (test/neg-blame
    '->i30
-   '((contract (->i ([x number?]) () #:rest rst number? any)
+   '((contract (->i ([x number?]) () #:rest [rst number?] any)
                (λ (x . rst) (values 4 5))
                'pos
                'neg)
@@ -2238,7 +2238,7 @@
 
   (test/pos-blame
    '->i-pp-r1
-   '((contract (->i ([x number?]) () #:rest rst any/c #:pre-cond (= x 1) [result number?] #:post-cond (= x 2))
+   '((contract (->i ([x number?]) () #:rest [rst any/c] #:pre-cond (= x 1) [result number?] #:post-cond (= x 2))
                (λ (x . rst) x)
                'pos
                'neg)
@@ -2246,7 +2246,7 @@
   
   (test/neg-blame
    '->i-pp-r2
-   '((contract (->i ([x number?]) () #:rest rst any/c #:pre-cond (= x 1)  [result number?] #:post-cond (= x 2))
+   '((contract (->i ([x number?]) () #:rest [rst any/c] #:pre-cond (= x 1)  [result number?] #:post-cond (= x 2))
                (λ (x . rst) x)
                'pos
                'neg)
@@ -2254,7 +2254,7 @@
   
   (test/pos-blame
    '->i-pp-r3
-   '((contract (->i ([x number?]) () #:rest rst any/c #:pre-cond (= x 1) [result number?] #:post-cond (= result 2))
+   '((contract (->i ([x number?]) () #:rest [rst any/c] #:pre-cond (= x 1) [result number?] #:post-cond (= result 2))
                (λ (x . rst) x)
                'pos
                'neg)
@@ -2262,7 +2262,7 @@
   
   (test/spec-passed
    '->i-pp-r3.5
-   '((contract (->i ([x number?]) () #:rest rst any/c #:pre-cond (= x 1) [result number?] #:post-cond (= result 2))
+   '((contract (->i ([x number?]) () #:rest [rst any/c] #:pre-cond (= x 1) [result number?] #:post-cond (= result 2))
                (λ (x . rst) 2)
                'pos
                'neg)
@@ -2270,7 +2270,7 @@
   
   (test/neg-blame
    '->i-pp-r4
-   '((contract (->i ([x number?]) () #:rest rst any/c #:pre-cond (= x 1) any)
+   '((contract (->i ([x number?]) () #:rest [rst any/c] #:pre-cond (= x 1) any)
                (λ (x . rst) x)
                'pos
                'neg)
@@ -2278,7 +2278,7 @@
   
   (test/neg-blame
    '->i-pp-r5
-   '((contract (->i ([x number?]) () #:rest rst any/c #:pre-cond (= x 1) (values [z number?] [y number?]) #:post-cond (= x y z 3))
+   '((contract (->i ([x number?]) () #:rest [rst any/c] #:pre-cond (= x 1) (values [z number?] [y number?]) #:post-cond (= x y z 3))
                (λ (x . rst) (values 4 5))
                'pos
                'neg)
@@ -2286,7 +2286,7 @@
   
   (test/pos-blame
    '->i-pp-r6
-   '((contract (->i ([x number?]) () #:rest rst any/c #:pre-cond (= x 1) (values [z number?] [y number?]) #:post-cond (= z x y 3))
+   '((contract (->i ([x number?]) () #:rest [rst any/c] #:pre-cond (= x 1) (values [z number?] [y number?]) #:post-cond (= z x y 3))
                (λ (x . rst) (values 4 5))
                'pos
                'neg)
@@ -2313,7 +2313,7 @@
   
   (test/spec-passed
    '->i-optopt2
-   '((contract (->i ([x number?]) #:rest rst any/c any)
+   '((contract (->i ([x number?]) #:rest [rst any/c] any)
                (λ (x . y) x)
                'pos 'neg)
      1))
@@ -2327,21 +2327,21 @@
   
   (test/spec-passed
    '->i-optopt4
-   '((contract (->i ([x number?]) #:rest rst any/c #:pre-cond #t any)
+   '((contract (->i ([x number?]) #:rest [rst any/c] #:pre-cond #t any)
                (λ (x . y) x)
                'pos 'neg)
      1))
   
   (test/spec-passed
    '->i-optopt5
-   '((contract (->i ([x number?]) #:rest rst any/c #:pre-cond #t [res any/c] #:post-cond #t)
+   '((contract (->i ([x number?]) #:rest [rst any/c] #:pre-cond #t [res any/c] #:post-cond #t)
                (λ (x . y) x)
                'pos 'neg)
      1))
   
   (test/spec-passed
    '->i-optopt6
-   '((contract (->i ([x number?]) #:rest rst any/c [res any/c] #:post-cond #t)
+   '((contract (->i ([x number?]) #:rest [rst any/c] [res any/c] #:post-cond #t)
                (λ (x . y) x)
                'pos 'neg)
      1))
@@ -2368,7 +2368,7 @@
   
   (test/spec-passed
    '->i-binding1
-   '((contract (->i ([x number?]) () #:rest rest any/c [range any/c] #:post-cond (equal? rest '(2 3 4)))
+   '((contract (->i ([x number?]) () #:rest [rest any/c] [range any/c] #:post-cond (equal? rest '(2 3 4)))
                (λ (x . y) y)
                'pos
                'neg)
@@ -2376,7 +2376,7 @@
   
   (test/spec-passed
    '->i-binding2
-   '((contract (->i ([x number?]) () #:rest rest any/c [range any/c] #:post-cond (equal? x 1))
+   '((contract (->i ([x number?]) () #:rest [rest any/c] [range any/c] #:post-cond (equal? x 1))
                (λ (x . y) y)
                'pos
                'neg)
@@ -2389,7 +2389,7 @@
           [r 'r])
       ((contract (->i ([x number?] [y number?] #:z [z number?] #:w [w number?]) 
                       ([a number?] [b number?] #:c [c number?] #:d [d number?])
-                      #:rest rest any/c 
+                      #:rest [rest any/c] 
                       #:pre-cond (equal? (list x y z w a b c d rest p q r)
                                          (list 1 2 3 4 5 6 7 8 '(z) 'p 'q 'r))
                       (values [p number?] [q number?] [r number?]))
@@ -2403,7 +2403,7 @@
    '->i-binding4
    '((contract (->i ([x number?] [y number?] #:z [z number?] #:w [w number?]) 
                     ([a number?] [b number?] #:c [c number?] #:d [d number?])
-                    #:rest rest any/c 
+                    #:rest [rest any/c] 
                     (values [p number?] [q number?] [r number?])
                     #:post-cond (equal? (list x y z w a b c d rest p q r)
                                         (list 1 2 3 4 5 6 7 8 '(z) 11 12 13)))
@@ -2420,7 +2420,7 @@
           [r 'r])
       ((contract (->i ([x number?] [y number?] #:z [z number?] #:w [w number?]) 
                       ([a number?] [b number?] #:c [c number?] #:d [d number?])
-                      #:rest rest any/c 
+                      #:rest [rest any/c] 
                       #:pre-cond (equal? (list x y z w a b c d rest p q r)
                                          (list 1 2 3 4 
                                                the-unsupplied-arg the-unsupplied-arg the-unsupplied-arg the-unsupplied-arg
@@ -2436,7 +2436,7 @@
    '->i-binding6
    '((contract (->i ([x number?] [y number?] #:z [z number?] #:w [w number?]) 
                     ([a number?] [b number?] #:c [c number?] #:d [d number?])
-                    #:rest rest any/c 
+                    #:rest [rest any/c] 
                     (values [p number?] [q number?] [r number?])
                     #:post-cond (equal? (list x y z w a b c d rest p q r)
                                         (list 1 2 3 4
@@ -2453,7 +2453,7 @@
    '->i-binding7
    '((contract (->i () 
                     ([a number?])
-                    #:rest rest any/c 
+                    #:rest [rest any/c] 
                     [_ any/c]
                     #:post-cond (equal? (list a rest) (list the-unsupplied-arg '())))
                (λ ([a 1] . rest) 1)
@@ -2497,7 +2497,7 @@
   
   (test/spec-passed/result
    '->i-underscore4
-   '((contract (->i ([str any/c]) () #:rest rest (listof any/c) [_ any/c])
+   '((contract (->i ([str any/c]) () #:rest [rest (listof any/c)] [_ any/c])
                (λ (x . y) (cons x y))
                'pos 'neg)
      1 2 3)
@@ -2505,7 +2505,7 @@
   
   (test/spec-passed/result
    '->i-underscore5
-   '((contract (->i ([str any/c]) () #:rest rest (listof any/c) [_ any/c])
+   '((contract (->i ([str any/c]) () #:rest [rest (listof any/c)] [_ any/c])
                (λ (x . y) (cons x y))
                'pos 'neg)
      1 2 3 4 5)
@@ -4876,7 +4876,7 @@
   
   (test/spec-passed
    'object-contract-->i3
-   '(send (contract (object-contract (m (->i () () #:rest rst (listof number?) [range any/c])))
+   '(send (contract (object-contract (m (->i () () #:rest [rst (listof number?)] [range any/c])))
                     (new (class object% (define/public m (lambda w 1)) (super-new)))
                     'pos
                     'neg)
@@ -4885,7 +4885,7 @@
   
   (test/neg-blame
    'object-contract-->i4
-   '(send (contract (object-contract (m (->i () () #:rest rst (listof number?) [range any/c])))
+   '(send (contract (object-contract (m (->i () () #:rest [rst (listof number?)] [range any/c])))
                     (new (class object% (define/public m (lambda w 1)) (super-new)))
                     'pos 
                     'neg)
@@ -4942,7 +4942,7 @@
    'object-contract-->i/this-3
    '(send (contract (object-contract (m (->i ([x (and/c integer? (lambda (x) (= x (get-field f this))))])
                                              ()
-                                             #:rest rest-var any/c
+                                             #:rest [rest-var any/c]
                                              any)))
                     (new (class object% (field [f 1]) (define/public m (lambda (x . rest) 1)) (super-new)))
                     'pos
@@ -4954,7 +4954,7 @@
    'object-contract-->i/this-4
    '(send (contract (object-contract (m (->i ([x (and/c integer? (lambda (x) (= x (get-field f this))))])
                                              ()
-                                             #:rest rest-var any/c
+                                             #:rest [rest-var any/c]
                                              any)))
                     (new (class object% (field [f 1]) (define/public m (lambda (x . rest) 1)) (super-new)))
                     'pos
@@ -5005,7 +5005,7 @@
   
   (test/spec-passed
    'object-contract-->i-pp3
-   '(send (contract (object-contract (m (->i () () #:rest rst (listof number?) #:pre-cond #t [unused any/c] #:post-cond #t)))
+   '(send (contract (object-contract (m (->i () () #:rest [rst (listof number?)] #:pre-cond #t [unused any/c] #:post-cond #t)))
                     (new (class object% (define/public m (lambda w 1)) (super-new)))
                     'pos
                     'neg)
@@ -5014,7 +5014,7 @@
   
   (test/neg-blame
    'object-contract-->i-pp4
-   '(send (contract (object-contract (m (->i () () #:rest rst (listof number?) #:pre-cond #t [unused any/c] #:post-cond #t)))
+   '(send (contract (object-contract (m (->i () () #:rest [rst (listof number?)] #:pre-cond #t [unused any/c] #:post-cond #t)))
                     (new (class object% (define/public m (lambda w 1)) (super-new)))
                     'pos 
                     'neg)
@@ -5082,7 +5082,7 @@
   (test/neg-blame
    'object-contract-->i-pp/this-4
    '(send (contract (object-contract (m (->i () ()
-                                             #:rest rest-id any/c
+                                             #:rest [rest-id any/c]
                                              #:pre-cond (= 1 (get-field f this))
                                              [result-x any/c]
                                              #:post-cond (= 2 (get-field f this)))))
@@ -5094,7 +5094,7 @@
   (test/pos-blame
    'object-contract-->i-pp/this-5
    '(send (contract (object-contract (m (->i () ()
-                                             #:rest rest-id any/c
+                                             #:rest [rest-id any/c]
                                              #:pre-cond (= 1 (get-field f this))
                                              [result-x any/c]
                                              #:post-cond (= 2 (get-field f this)))))
@@ -5106,7 +5106,7 @@
   (test/spec-passed
    'object-contract-->i-pp/this-6
    '(send (contract (object-contract (m (->i () ()
-                                             #:rest rest-id any/c
+                                             #:rest [rest-id any/c]
                                              #:pre-cond (= 1 (get-field f this))
                                              [result-x any/c]
                                              #:post-cond (= 2 (get-field f this)))))
@@ -8529,8 +8529,8 @@ so that propagation occurs.
   (test-name '(object-contract (m (->i ((x ...)) () (y ...)))) (object-contract (m (->i ((x number?)) () [result number?]))))
   (test-name '(object-contract (m (->i ((x ...) (y ...) (z ...)) () [w ...])))
              (object-contract (m (->i ((x number?) (y boolean?) (z pair?)) () [result number?]))))
-  (test-name '(object-contract (m (->i ((x ...) (y ...) (z ...)) () #:rest w ... [x0 ...])))
-             (object-contract (m (->i ((x number?) (y boolean?) (z pair?)) () #:rest rest-x any/c [result number?]))))
+  (test-name '(object-contract (m (->i ((x ...) (y ...) (z ...)) () #:rest [w ...] [x0 ...])))
+             (object-contract (m (->i ((x number?) (y boolean?) (z pair?)) () #:rest [rest-x any/c] [result number?]))))
 |#
 
   (test-name '(promise/c any/c) (promise/c any/c))