separate `shift` into `shift` and `shifts`

sugar/list.rkt

@@ -26,15 +26,15 @@
               values->list
               [sublist (list? index? index? . -> . list?)]
               [break-at (list? (and/c coerce/list? (or/c empty? increasing-nonnegative-list?)) . -> . list-of-lists?)]
-              [shift ((list? (or/c integer? integers?)) (any/c boolean?) . ->* . list?)]
-              [shift/values ((list? (or/c integer? integers?)) (any/c) . ->* . any)])
+              [shift ((list? integer?) (any/c boolean?) . ->* . list?)]
+              [shifts ((list? integers?) (any/c boolean?) . ->* . (listof list?))]
+              [shift/values ((list? (or/c integers? integer?)) (any/c boolean?) . ->* . any)])
 
 
 ;; todo: can this work in typed context? couldn't figure out how to polymorphically `apply values`
 ;; macro doesn't work either
-(define (shift/values xs shift-amount-or-amounts [fill-item #f])
-  (apply (if (list? shift-amount-or-amounts) 
-             values
-             (λ xs xs)) 
-         (shift xs shift-amount-or-amounts fill-item)))
+(define (shift/values xs shift-amount-or-amounts [fill-item #f] [cycle #f])
+  (apply values ((if (list? shift-amount-or-amounts)
+                     shifts
+                     shift) xs shift-amount-or-amounts fill-item cycle)))
 

sugar/scribblings/list.scrbl

@@ -188,31 +188,52 @@ Break @racket[_lst] into smaller lists at the index positions in @racket[_indexe
 @defproc[
 (shift
 [lst list?]
-[how-far (or/c integer? (listof integer?))]
-[fill-item any/c #f])
-(or/c list? (listof list?))]
-Move the items in @racket[_lst] to the right (if @racket[_how-far] is positive) or left (if negative). Vacated spaces in the list are filled with @racket[_fill-item], so the result list is always the same length as the input list. (If you don't care about the lengths being the same, you probably want @racket[take] or @racket[drop] instead.) If @racket[_how-far] is a list rather than a single value, return a list of lists shifted by the designated amounts. If @racket[_how-far] is 0, return the original list. If @racket[_how-far] is bigger than the length of @racket[_lst], raise an error.
+[how-far integer?]
+[fill-item any/c #f]
+[cycle? boolean? #f])
+list?]
+Move the items in @racket[_lst] to the right (if @racket[_how-far] is positive) or left (if @racket[_how-far] is negative). By default, vacated spaces in the list are filled with @racket[_fill-item]. But if @racket[_cycle?] is true, elements of the list wrap around (and @racket[_fill-item] is ignored). Either way, the result list is always the same length as the input list. (If you don't care about the lengths being the same, you probably want @racket[take] or @racket[drop] instead.) If @racket[_how-far] is 0, return the original list. If @racket[_how-far] is bigger than the length of @racket[_lst], raise an error.
 
 @examples[#:eval my-eval
 (define xs (range 5))
 (shift xs 2)
 (shift xs -2 0)
-(shift xs '(-1 0 1) 'boing)
+(shift xs 2 'boing)
+(shift xs 2 'boing #t)
 (shift xs 0)
 (shift xs 42)
 ]
 
+@defproc[
+(shifts
+[lst list?]
+[how-far (listof integer?)]
+[fill-item any/c #f]
+[cycle? boolean? #f])
+(listof list?)]
+Same as @racket[shift], but @racket[_how-far] is a list of integers rather than a single integer, and the result is a list of lists rather than a single list.
+
+@examples[#:eval my-eval
+(define xs (range 5))
+(shifts xs '(-2 2))
+(shifts xs '(-2 2) 0)
+(shifts xs '(-2 2) 'boing)
+(shifts xs '(-2 2) 'boing #t)
+]
+
 @defproc[
 (shift/values
 [lst list?]
 [how-far (or/c integer? (listof integer?))]
 [fill-item any/c #f])
 any]
-@bold{Untyped only.} Same as @racket[shift], except that when @racket[_how-far] is a list, the resulting lists are returned as multiple values rather than as a list of lists.
+@bold{Untyped only.} When @racket[_how-far] is a single integer, same as @racket[shift], but the resulting list is returned as values. When @racket[_how-far] is a list of integers, same as @racket[shifts], but the resulting lists are returned as multiple values rather than as a list of lists.
 
 @examples[#:eval my-eval
 (define xs (range 5))
-(shift xs '(-1 0 1))
+(shift xs 1)
+(shift/values xs 1)
+(shifts xs '(-1 0 1))
 (shift/values xs '(-1 0 1))
 ]
 

sugar/test/main.rkt

@@ -166,11 +166,15 @@
  
  (define xs (range 5))
  (check-equal? (map (λ(a b c) (list a b c)) (shift xs -1) (shift xs 0) (shift xs 1)) '((1 0 #f) (2 1 0) (3 2 1) (4 3 2) (#f 4 3)))
- (check-equal? (shift xs '(-1 0 1) 'boing)  `((1 2 3 4 boing) ,xs (boing 0 1 2 3)))
- (check-equal? (shift xs 5 0) (make-list 5 0))
+ (check-equal? (map (λ(a b c) (list a b c)) (shift xs -1 'ignored #t) (shift xs 0 'ignored #t) (shift xs 1 'ignored #t)) '((1 0 4) (2 1 0) (3 2 1) (4 3 2) (0 4 3)))
+ (check-equal? (shifts xs '(-1 0 1) 'boing)  `((1 2 3 4 boing) ,xs (boing 0 1 2 3)))
+(check-equal? (shifts xs '(-1 0 1) 'boing #t)  `((1 2 3 4 0) ,xs (4 0 1 2 3)))
+(check-equal? (shift xs 5 0) (make-list 5 0))
  (check-exn exn:fail? (λ() (shift xs -10))))
 
 
+
+
 (eval-as-untyped
  (check-equal? (filter-split '("foo" " " "bar" "\n" "\n" "ino") (λ(x) (< (string-length x) 3))) '(("foo")("bar")("ino")))
  
@@ -215,6 +219,7 @@
  
  (define xs (range 5))
  (define ys (range 5))
+ (check-equal? (values->list (shift/values ys -1 'boing)) '(1 2 3 4 boing)) 
  (check-equal? (values->list (shift/values ys '(-1 0 1) 'boing)) `((1 2 3 4 boing) ,xs (boing 0 1 2 3))) 
  
  (require xml)

typed/sugar/list.rkt

@@ -166,25 +166,39 @@
 
 
 (define/typed+provide shift
-  (All (A) (case-> ((Listof (Option A)) (U Integer (Listof Integer)) -> (U (Listof (Option A)) (Listof (Listof (Option A)))))
-                   ((Listof (Option A)) (U Integer (Listof Integer)) (Option A) -> (U (Listof (Option A)) (Listof (Listof (Option A)))))
-                   ((Listof (Option A)) (U Integer (Listof Integer)) (Option A) Boolean -> (U (Listof (Option A)) (Listof (Listof (Option A)))))))  
+  (All (A) (case-> ((Listof (Option A)) Integer -> (Listof (Option A)))
+                   ((Listof (Option A)) Integer (Option A) -> (Listof (Option A)))
+                   ((Listof (Option A)) Integer (Option A) Boolean -> (Listof (Option A)))))  
   (case-lambda
-    [(xs shift-amount-or-amounts)
-     (shift xs shift-amount-or-amounts #f #f)]
-    [(xs shift-amount-or-amounts fill-item)
-     (shift xs shift-amount-or-amounts fill-item #f)]
-    [(xs shift-amount-or-amounts fill-item cycle)
-     (define/typed (do-shift xs fill-item how-far)
-       (All (A2) ((Listof (Option A2)) (Option A2) Integer -> (Listof (Option A2))))
+    [(xs how-far)
+     (shift xs how-far #f #f)]
+    [(xs how-far fill-item)
+     (shift xs how-far fill-item #f)]
+    [(xs how-far fill-item cycle)
      (define abs-how-far (abs how-far))
      (cond 
        [(> abs-how-far (length xs)) (error 'shift "index is too large for list\nindex: ~a\nlist: ~v" how-far xs)]
        [(= how-far 0) xs]
        [(positive? how-far)
-          ((inst append (Option A2)) ((inst make-list (Option A2)) abs-how-far fill-item) (drop-right xs abs-how-far))]
-         ;; otherwise how-far is negative
-         [else  (append (drop xs abs-how-far) (make-list abs-how-far fill-item))]))
-     (if (list? shift-amount-or-amounts)
-         ((inst map (Listof (Option A)) Integer) (λ:([amount : Integer]) (do-shift xs fill-item amount)) shift-amount-or-amounts)
-         (do-shift xs fill-item shift-amount-or-amounts))]))
+        (define filler (if cycle
+                           (take-right xs abs-how-far)
+                           (make-list abs-how-far fill-item)))            
+        (append filler (drop-right xs abs-how-far))]
+       [else ; how-far is negative
+        (define filler (if cycle
+                           (take xs abs-how-far)
+                           (make-list abs-how-far fill-item)))
+        (append (drop xs abs-how-far) filler)])]))
+
+(define/typed+provide shifts
+  (All (A) (case-> ((Listof (Option A)) (Listof Integer) -> (Listof (Listof (Option A))))
+                   ((Listof (Option A)) (Listof Integer) (Option A) -> (Listof (Listof (Option A))))
+                   ((Listof (Option A)) (Listof Integer) (Option A) Boolean -> (Listof (Listof (Option A))))))
+  (case-lambda
+    [(xs how-fars)
+     (shifts xs how-fars #f #f)]
+    [(xs how-fars fill-item)
+     (shifts xs how-fars fill-item #f)]
+    [(xs how-fars fill-item cycle)
+     (map (λ:([how-far : Integer]) (shift xs how-far fill-item cycle)) how-fars)]))
+