From e650a80856edc1d1df1f163c3f84082455717fa0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hugo=20H=C3=B6rnquist?= <hugo@lysator.liu.se>
Date: Mon, 18 Mar 2019 18:43:51 +0100
Subject: Compleately redid file structure.

---
 monad/either.scm | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 monad/either.scm

(limited to 'monad/either.scm')

diff --git a/monad/either.scm b/monad/either.scm
new file mode 100644
index 0000000..c597a60
--- /dev/null
+++ b/monad/either.scm
@@ -0,0 +1,30 @@
+;;; TODO UNFINISHED
+
+(define-module (data either)
+  #:use-module (oop goops)
+  #:use-module (ice-9 match))
+
+(define-class <either> ()
+  (slot #:init-keyword #:slot)
+  (dir #:init-keyword #:dir #:init-value 'left))
+
+(define (left val)
+  "Error values"
+  (make <either> #:slot val #:dir 'left))
+
+(define (right val)
+  "Good values"
+  (make <either> #:slot val #:dir 'right))
+
+(define-method (write (this <either>) port)
+  (format port "[~a ~s]"
+          (slot-ref this 'dir)
+          (slot-ref this 'slot)))
+
+(define-method (>>= (this <either>)
+                    (proc <procedure>))
+  (case (slot-ref this 'dir)
+    ((left) this)
+    ((right) (match this (($ <either> slot) (proc slot))))))
+
+(define return-either right)
-- 
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