From d86d88b96cd7aba976ab58b909fd4eae48323bb0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hugo=20H=C3=B6rnquist?= <hugo@hornquist.se>
Date: Sat, 10 Nov 2018 23:57:53 +0100
Subject: Add >>, fix do to use it.

---
 control/monad/procedures.scm | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

(limited to 'control/monad')

diff --git a/control/monad/procedures.scm b/control/monad/procedures.scm
index 701f871..2c25d57 100644
--- a/control/monad/procedures.scm
+++ b/control/monad/procedures.scm
@@ -1,17 +1,22 @@
 (define-module (control monad procedures)
   #:use-module (oop goops)
   #:use-module (srfi srfi-1)            ; concatenate!
-  #:export (>>=))
+  #:export (>> >>=))
 
 (define-generic >>=)
 
-(define-method (>>= (this <null>)
-                    proc)
-  '())
+(define-method (>>= (this <null>) proc) '())
 (define-method (>>= (this <pair>)
                     (proc <procedure>))
   (concatenate! (map proc this)))
 
+(define-generic >>)
+(define-method (>> (a <null>) (b <null>)) '())
+(define-method (>> (a <pair>) (b <null>)) '())
+(define-method (>> (a <null>) (b <pair>)) '())
+(define-method (>> (a <pair>) (b <pair>))
+  (concatenate! (map (constant b) a)))
+
 ;; bind :: Monad m => m a -> (a -> m b) -> m b
 ;; return :: Monad m => a -> m a
 ;; map :: Functor f => (a -> b) -> f a -> f b
-- 
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