1 files changed, 17 insertions, 0 deletions
diff --git a/algebraic-structures.private.stream.applicative.scm b/algebraic-structures.private.stream.applicative.scm
new file mode 100644
index 0000000..0389ad9
--- /dev/null
+++ b/algebraic-structures.private.stream.applicative.scm
@@ -0,0 +1,17 @@
+(module (algebraic-structures private stream applicative) ()
+  (import scheme
+          (srfi 41)
+          (only (chicken base) cute)
+          (chicken module))
+  (export pure map2)
+  (reexport (algebraic-structures stream functor))
+
+  (define (pure x) (stream x))
+
+  (define-stream (product op s1 s2)
+    (if (stream-null? s1)
+        stream-null
+        (stream-append (stream-map (cute op (stream-car s1) <>) s2)
+                       (product op (stream-cdr s1) s2))))
+
+  (define map2 product))