adding CodingStyle.

CodingStyle

@@ -0,0 +1,45 @@
+* GHC support
+
+GHC 7.4, 7.6 and 7.8 are supported at this moment.  If GHC 7.10 is
+released, the support for GHC 7.4 will be discontinued.
+
+
+* Compiler warnings
+
+All compiler warnings generated by the latest stable GHC with "-Wall"
+MUST be eliminated.
+
+
+* Deceleration style
+
+Try to use "where" instead of "let".
+
+
+* Error handling
+
+As a general rule of thumb anything that can fail (as in the Monad
+method) should get a surrounding catchError with a description of what
+the function was trying to do. If a function is trying to do more than
+one thing it should probably be split up into multiple seperate
+functions anyways.
+
+All uses of the major partial functions (i.e fromJust, fromLeft, head
+etc.) should probably be replaced by pattern matching in the do block
+(since pattern match failures are very easy to handle with
+catchError).
+
+We also have to be careful with anything that uses liftIO since that
+might introduce unexpected exceptions. For example parseCabalFile
+still uses IOError's for error reporting which would circumvent ErrorT
+and make handling that error with MonadError impossible. Stuff like
+that should probably be converted to GhcModT or return IO (Either
+String SomeThing) instead. It should be pretty easy to write a
+function to lift IO (Either e a) into a GhcModT a (where e could be
+String, ´GhcModError` or something like that).
+
+
+* #if
+
+"#if __GLASGOW_HASKELL__" should be used in "Gap.hs" and "Monad.hs"
+only. If it is used in another file, it should be moved into
+"Gap.hs".