1 files changed, 155 insertions, 0 deletions
diff --git a/modules/language/python/module/itertools.scm b/modules/language/python/module/itertools.scm
new file mode 100644
index 0000000..d333ee9
--- /dev/null
+++ b/modules/language/python/module/itertools.scm
@@ -0,0 +1,155 @@
+(define-module (language python module itertools)
+  #:use-module (language python for)
+  #:use-module (language python yield)
+  #:use-module (language python def)
+  #:use-module (language python module copy)
+  #:use-module (language python module python)
+  #:use-module (language python module copy)
+  #:export (count cycle repeat accumulate chain compress dropwhile
+		  filterfalse groupby isslice starmap takewhile
+		  tee zip_longest))
+
+(define count
+  (make-generator (start #:optional (step 1))
+    (lambda* (yield start #:optional (step 1))
+      (let lp ((i start))
+	(yield i)
+	(lp (+ i step))))))
+
+(define cycle
+  (make-generator
+   (lambda (yield p)
+     (let lp ()
+       (for ((x : p)) () (yield x))
+       (lp)))))
+
+(define repeat
+  (make-generator
+   (lambda* (yield e #:optional (n -1))
+     (let lp ((i 0))
+       (if (not (= i n))
+	   (begin
+	     (yield e)
+	     (lp (+ i 1))))))))
+
+(define accumulate
+  (make-generator
+   (lambda* (yield p #:optional (f +))
+     (for ((x : p)) ((s 0) (first? #t))
+	  (if first?
+	      (begin
+		(yield x)
+		(values x #f))
+	      (let ((s (f x s)))
+		(yield s)
+		(values s #f)))))))
+
+(define-python-class chain ()
+  (define __call__
+    (make-generator
+     (lambda (yield . l)
+       (let lp ((l l))
+	 (if (pair? l)
+	     (begin
+	       (for ((x : (car l))) ()
+		    (yield x))
+	       (lp (cdr l))))))))
+  (define from_iterable
+    (make-generator
+     (lambda (yield i)
+       (for ((ii : i)) ()
+	    (for ((x : ii)) ()
+		 (yield x)))))))
+
+(define compress
+  (make-generator
+   (lambda (yield data selectors)
+     (for ((d : data) (s : selectors)) ()
+	  (if s (yield d))))))
+
+(define dropwhile
+  (make-generator
+   (lambda (yield pred seq)
+     (for ((x : seq)) ((start? #f))
+	  (if start?
+	      (begin
+		(yield x)
+		#t)
+	      (if (pred x)
+		  #f
+		  (begin
+		    (yield x)
+		    #t)))))))
+
+(define filterfalse
+  (make-generator
+   (lambda (yield pred seq)
+     (for ((x : seq))
+	  (if (not (f x)) (yield x))))))
+
+(define none (list 'none))
+(define groupby
+  (make-generator
+   (lambda* (yield seq #:optional (key (lambda (x) x)))
+     (for ((x : seq)) ((k none)) ((l '()))
+	  (if (eq? k none)
+	      (values (key x) (list x))
+	      (let ((kk (key x)))
+		(if (equal? k kk)
+		    (values k (cons x l))
+		    (begin
+		      (yield k (reverse l))
+		      (values kk (list x))))))
+	  #:final
+	  (if (not (eq? k none))
+	      (yield l (reverse l)))))))
+     
+     
+(define isslice
+  (make-generator
+   (lambda* (yield seq #:optional (start 0) (stop -1) (step 1))
+     (for ((x : seq) (i : (count 0)))
+	  (if (= i stop) (break))
+	  (if (and (>= i start)
+		   (= (modulo (- i start) step) 0))
+	      (yield x))))))
+
+(define starmap
+  (make-generator
+   (lambda (yield f seq)
+     (for ((x : seq)) () (yield (f x))))))
+
+(define takewhile
+  (make-generator
+   (lambda (yield pred seq)
+     (for ((x : seq)) ()
+	  (if (not (pred x)) (break))
+	  (yield x)))))
+  
+(define tee
+  (make-generator
+   (lambda (yield it n)
+     (let lp ((i 0))
+       (if (< i n)
+	   (cons (deepcopy it)
+		 (lp (+ i 1)))
+	   '())))))
+
+(define zip_longest
+  (make-generator
+   (lam (yield (* l) (= fillvalue None))
+	(define mkit
+	  (make-generator
+	   (lambda (yield it)
+	     (for ((x : it)) ()
+		  (yield (cons 1 x))
+	     (let lp ()
+	       (yield (cons 0 0))
+	       (lp)))))
+	  (for ((x : (apply zip (map mkit l))))
+	       (if (= (apply + (map car x)) 0)
+		   (break)
+		   (yield (map (lambda (x) (if (= (car x) 0) fillvalue (cdr x)))
+			       x))))))))
+	
+