X-Git-Url: https://gerrit.simantics.org/r/gitweb?a=blobdiff_plain;f=bundles%2Forg.simantics.scl.runtime%2Fscl%2FPrelude.scl;h=dc25349c8c04da7beab8d8b0d7d8df1187213381;hb=a472ceaa29534d553e2af893e268b6a13bffa441;hp=c175f95a30d01bd7a15c0c6e9d8d4fd1dc36ef1d;hpb=fcb5a762af707ecef245fb3b83a36e8b24bc4b47;p=simantics%2Fplatform.git

diff --git a/bundles/org.simantics.scl.runtime/scl/Prelude.scl b/bundles/org.simantics.scl.runtime/scl/Prelude.scl
index c175f95a3..dc25349c8 100644
--- a/bundles/org.simantics.scl.runtime/scl/Prelude.scl
+++ b/bundles/org.simantics.scl.runtime/scl/Prelude.scl
@@ -75,7 +75,7 @@ infixl 6  (+), (-)
 infixl 5  (\\), (<<), (<+)
 infix  4  (!=), (<), (<=), (>=), (>)
 infixr 3  (&&), (&<&)
-infixr 2  (||), orElse, morelse
+infixr 2  (||), orElse, orElseM, morelse
 infixr 1  (>>=), (>>), (:=), (>=>)
 infixr 1  ($)
 infixl 1  catch
@@ -1096,6 +1096,7 @@ class (FunctorE f) => FunctorM f where
 /// MonadE ///
 
 class (FunctorE m, Monad m) => MonadE m where
+    "An effectful version of the bind operator `(>>=)`"
     bindE :: m a -> (a -> <e> m b) -> <e> m b
 
 instance MonadE Maybe where
@@ -1109,6 +1110,11 @@ instance MonadE (Either a) where
 instance MonadE [] where
     bindE l f = concatMap f l
 
+@inline
+"An effectful version of the Kleisli composition operator `(>=>)`"
+compE :: MonadE m => (a -> <e> m b) -> (b -> <f> m c) -> a -> <e,f> m c
+compE f g x = (f x) `bindE` g
+
 /// MZeroE ///
 
 class (MonadE m, MonadZero m) => MonadZeroE m where
@@ -1521,11 +1527,11 @@ snd :: (a,b) -> b
 snd (x,y) = y
 
 @inline
-mapFst :: (a -> b) -> (a,c) -> (b,c)
+mapFst :: (a -> <e> b) -> (a,c) -> <e> (b,c)
 mapFst f (x,y) = (f x, y)
 
 @inline
-mapSnd :: (a -> b) -> (c,a) -> (c,b)
+mapSnd :: (a -> <e> b) -> (c,a) -> <e> (c,b)
 mapSnd f (x,y) = (x, f y)
 
 instance (Ord a, Ord b) => Ord (a, b) where
@@ -2258,7 +2264,7 @@ importJava "java.lang.Throwable" where
     showThrowable :: Throwable -> String
     @private
     @JavaName getMessage 
-    getMessageThrowable :: Throwable -> String
+    getMessageThrowable :: Throwable -> Maybe String
     @private
     @JavaName getCause 
     getCauseThrowable :: Throwable -> Maybe Throwable
@@ -2277,7 +2283,12 @@ class Throwable e where
     toThrowable :: e -> Throwable
 
 messageOfException :: Throwable e => e -> String
-messageOfException = getMessageThrowable . toThrowable
+messageOfException e = match getMessageThrowable $ toThrowable e with
+                       Just m -> m
+                       Nothing -> ""
+                       
+possibleMessageOfException :: Throwable e => e -> Maybe String
+possibleMessageOfException e = getMessageThrowable $ toThrowable e
 
 causeOfException :: Throwable e => e -> Maybe Throwable
 causeOfException = getCauseThrowable . toThrowable