From fd5003036e1df12305586020d328d08ca36fe3a7 Mon Sep 17 00:00:00 2001
From: Mart Lubbers <mart@martlubbers.net>
Date: Thu, 14 Apr 2016 13:28:18 +0200
Subject: [PATCH] rwst

---
 rwst.dcl | 12 ++++++++++++
 rwst.icl | 27 +++++++++++++++++++++++++++
 2 files changed, 39 insertions(+)
 create mode 100644 rwst.dcl
 create mode 100644 rwst.icl

diff --git a/rwst.dcl b/rwst.dcl
new file mode 100644
index 0000000..9afc81c
--- /dev/null
+++ b/rwst.dcl
@@ -0,0 +1,12 @@
+definition module rwst
+
+from Data.Functor import class Functor
+from Data.Monoid import class Monoid, class Semigroup
+from Control.Applicative import class Applicative
+from Control.Monad import class Monad
+
+:: RWST r w s m a
+
+instance Functor (RWST r w s m) | Monad m & Monoid w
+instance Applicative (RWST r w s m) | Monad m & Monoid w
+instance Monad (RWST r w s m) | Monad m & Monoid w
diff --git a/rwst.icl b/rwst.icl
new file mode 100644
index 0000000..e5c1d7c
--- /dev/null
+++ b/rwst.icl
@@ -0,0 +1,27 @@
+implementation module rwst
+
+from Data.Func import $
+import Data.Functor
+import Data.Monoid
+import Control.Monad
+import Control.Applicative
+
+
+Start = "Test"
+
+:: RWST r w s m a = RWST (r s -> m (a, s, w))
+
+runRWST :: (RWST r w s m a) r s -> m (a, s, w)
+runRWST (RWST f) r s = f r s
+
+instance Functor (RWST r w s m) | Monad m & Monoid w where
+	fmap f m = liftM f m
+
+instance Applicative (RWST r w s m) | Monad m & Monoid w where
+    pure a = RWST \_ s->pure (a, s, mempty)
+	(<*>) mf mx = ap mf mx
+
+instance Monad (RWST r w s m) | Monad m & Monoid w where
+	bind m k = RWST \r s->runRWST m r s 
+		>>= \(a, s`, w)->runRWST (k a) r s`
+		>>= \(b, s``,w`)->pure (b, s``, mappend w w`)
-- 
2.20.1