From d46183860c1f3f10095e95023adcb79b1896ab0e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hugo=20H=C3=B6rnquist?= <hugo@lysator.liu.se>
Date: Fri, 22 Mar 2019 20:11:11 +0100
Subject: Move C and Scheme code into subdirs.

---
 module/srfi/srfi-41/util.scm | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)
 create mode 100644 module/srfi/srfi-41/util.scm

(limited to 'module/srfi/srfi-41')

diff --git a/module/srfi/srfi-41/util.scm b/module/srfi/srfi-41/util.scm
new file mode 100644
index 00000000..5bef95cb
--- /dev/null
+++ b/module/srfi/srfi-41/util.scm
@@ -0,0 +1,29 @@
+(define-module (srfi srfi-41 util)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-41)
+  #:use-module (util) ; let*, find-min
+  #:export (stream-car+cdr interleave-streams))
+
+(define (stream-car+cdr stream)
+  (values (stream-car stream)
+          (stream-cdr stream)))
+
+;; Merges a number of totally ordered streams into a single
+;; totally ordered stream.
+;; ((≺, stream)) → (≺, stream)
+(define (interleave-streams < streams)
+  ;; Drop all empty streams
+  (let ((streams (remove stream-null? streams)))
+    ;; If all streams where empty, end the output stream
+    (if (null? streams)
+        stream-null
+        (let* ((min other (find-min < stream-car streams))
+               (m ms (stream-car+cdr min)))
+          (stream-cons m (interleave-streams < (cons ms other)))))))
+
+;;; Varför är allting så långsamt‽‽‽‽‽‽‽‽
+
+(define-public (filter-sorted-stream proc stream)
+  (stream-take-while
+   proc (stream-drop-while
+         (negate proc) stream)))
-- 
cgit v1.2.3