From e9757cdfe5996d87738cabad84bff0343f56e4e3 Mon Sep 17 00:00:00 2001
From: jsimomaa <jani.simomaa@gmail.com>
Date: Thu, 4 Jan 2018 09:56:34 +0200
Subject: [PATCH] Add more Throwable & Exception handling functionality to
 Prelude

refs #7705

Change-Id: Ie335d3e8f7dacb0da66d0bb1491862fb054c61cb
---
 .../org.simantics.scl.runtime/scl/Prelude.scl | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/bundles/org.simantics.scl.runtime/scl/Prelude.scl b/bundles/org.simantics.scl.runtime/scl/Prelude.scl
index a926ae40e..eb8026de9 100644
--- a/bundles/org.simantics.scl.runtime/scl/Prelude.scl
+++ b/bundles/org.simantics.scl.runtime/scl/Prelude.scl
@@ -2214,6 +2214,12 @@ importJava "java.lang.Throwable" where
     @private
     @JavaName toString
     showThrowable :: Throwable -> String
+    @private
+    @JavaName getMessage 
+    getMessageThrowable :: Throwable -> String
+    @private
+    @JavaName getCause 
+    getCauseThrowable :: Throwable -> Maybe Throwable
 importJava "java.lang.Exception" where
     data Exception
     @private
@@ -2225,6 +2231,20 @@ instance Show Throwable where
 instance Show Exception where
     show = showException
 
+class Throwable e where
+    toThrowable :: e -> Throwable
+
+messageOfException :: Throwable e => e -> String
+messageOfException = getMessageThrowable . toThrowable
+
+causeOfException :: Throwable e => e -> Maybe Throwable
+causeOfException = getCauseThrowable . toThrowable
+
+instance Throwable Throwable where
+    toThrowable = id
+instance Throwable Exception where
+    toThrowable = Java.unsafeCoerce
+
 "Prints the given value in the console."
 @inline
 print :: Show a => a -> <Proc> ()
-- 
2.47.1