Single definition of (iota)

* module/ice-9/boot-9.scm (iota): Fix to be SRFI-1 compatible.
* module/srfi/srfi-1.scm: Re-export iota.

NEWS

@@ -4,6 +4,17 @@ See the end for copying conditions.
 
 Please send Guile bug reports to bug-guile@gnu.org.
 
+
+Changes since alpha 2.9.6:
+
+* Notable changes
+
+** (iota) in core and SRFI-1 (iota) are the same
+
+Previously, (iota) in core would not accept start and step arguments and
+would return an empty list for negative count. Now there is only one
+(iota) function with the semantics of SRFI-1 (negative count is an
+error).
 
 
 Changes in alpha 2.9.6 (since alpha 2.9.5):

module/ice-9/boot-9.scm

@@ -883,10 +883,15 @@ VALUE."
 ;;; {IOTA functions: generating lists of numbers}
 ;;;
 
-(define (iota n)
-  (let loop ((count (1- n)) (result '()))
-    (if (< count 0) result
-        (loop (1- count) (cons count result)))))
+;;;  Compatible with srfi-1 so it can just be reused there.
+
+(define* (iota count #:optional (start 0) (step 1))
+  (unless (and (integer? count) (>= count 0))
+    (throw 'wrong-type-arg count))
+  (let loop ((n (- count 1)) (result '()))
+    (if (negative? n)
+      result
+      (loop (- n 1) (cons (+ start (* n step)) result)))))
 
 
 

module/srfi/srfi-1.scm

@@ -48,7 +48,7 @@
  list-tabulate
  list-copy
  circular-list
- ;; iota				; Extended.
+ ;; iota				<= in the core
 
 ;;; Predicates
  proper-list?
@@ -216,8 +216,9 @@
 	      caaaar caaadr caadar caaddr cadaar cadadr caddar cadddr
 	      cdaaar cdaadr cdadar cdaddr cddaar cddadr cdddar cddddr
 	      list-ref last-pair length append append! reverse reverse!
-	      filter filter! memq memv assq assv set-car! set-cdr!)
-  :replace (iota map for-each map-in-order list-copy list-index member
+	      filter filter! memq memv assq assv set-car! set-cdr!
+              iota)
+  :replace (map for-each map-in-order list-copy list-index member
 	    delete delete! assoc)
   )
 
@@ -266,13 +267,6 @@ INIT-PROC is applied to the indices is not specified."
   (set-cdr! (last-pair elts) elts)
   elts)
 
-(define* (iota count #:optional (start 0) (step 1))
-  (check-arg non-negative-integer? count iota)
-  (let lp ((n 0) (acc '()))
-    (if (= n count)
-	(reverse! acc)
-	(lp (+ n 1) (cons (+ start (* n step)) acc)))))
-
 ;;; Predicates
 
 (define (proper-list? x)