General refactor for legibility

Priming to update all source to lhs and document extensively

src/REPL.hs

@@ -20,37 +20,36 @@ repl env = runInputT defaultSettings (loop env)
     loop :: Env -> InputT IO ()
     loop env = do
       minput <- getInputLine "tricu < "
-      case minput of
-        Nothing -> outputStrLn "Exiting tricu"
-        Just s -> case strip s of 
-          "!exit" -> outputStrLn "Exiting tricu"
-          "!load" -> do
-            path <- getInputLine "File path to load < "
-            case path of
-              Nothing -> do
-                outputStrLn "No input received; stopping import."
-                loop env
-              Just path -> do
-                loadedEnv <- liftIO $ evaluateFileWithContext env (strip path)
-                loop $ Map.delete "__result" (Map.union loadedEnv env)
-          "" -> do
-            outputStrLn ""
-            loop env
-          input -> do
-            case (take 2 input) of 
-              "--" -> loop env
-              _ -> do
-                newEnv <- liftIO $ (processInput env input `catch` errorHandler env)
-                loop newEnv
-  
+      if
+        | Nothing <- minput                     -> outputStrLn "Exiting tricu"
+        | Just s  <- minput, strip s == "!exit" -> outputStrLn "Exiting tricu"
+        | Just s  <- minput, strip s == ""      -> do
+          outputStrLn ""
+          loop env
+        | Just s  <- minput, strip s == "!load" -> do
+          path <- getInputLine "File path to load < "
+          if
+            | Nothing <- path -> do
+              outputStrLn "No input received; stopping import."
+              loop env
+            | Just p  <- path -> do
+              loadedEnv <- liftIO $ evaluateFileWithContext env (strip p) `catch` \e -> errorHandler env e
+              loop $ Map.delete "__result" (Map.union loadedEnv env)
+        | Just s <- minput -> do
+          if
+            | take 2 s == "--" -> loop env
+            | otherwise -> do
+              newEnv <- liftIO $ processInput env s `catch` errorHandler env
+              loop newEnv
+
     processInput :: Env -> String -> IO Env
     processInput env input = do
-      let asts = parseTricu input
+      let asts   = parseTricu input
           newEnv = evalTricu env asts
-      case Map.lookup "__result" newEnv of
-        Just r -> do
+      if
+        | Just r <- Map.lookup "__result" newEnv -> do
           putStrLn $ "tricu > " ++ decodeResult r
-        Nothing -> return ()
+        | otherwise -> return ()
       return newEnv
     
     errorHandler :: Env -> SomeException -> IO (Env)
@@ -62,10 +61,8 @@ repl env = runInputT defaultSettings (loop env)
     strip = dropWhileEnd isSpace . dropWhile isSpace
 
 decodeResult :: T -> String
-decodeResult tc = case toNumber tc of
-  Right num -> show num
-  Left _ -> case toString tc of
-    Right str -> "\"" ++ str ++ "\""
-    Left _ -> case toList tc of
-      Right list -> "[" ++ intercalate ", " (map decodeResult list) ++ "]"
-      Left _ -> formatResult TreeCalculus tc
+decodeResult tc
+  | Right num  <- toNumber tc = show num
+  | Right str  <- toString tc = "\"" ++ str ++ "\""
+  | Right list <- toList tc   = "[" ++ intercalate ", " (map decodeResult list) ++ "]"
+  | otherwise                 = formatResult TreeCalculus tc