General refactor for legibility

Priming to update all source to lhs and document extensively

src/Parser.hs

@@ -17,18 +17,20 @@ type AltParser = Parsec Void String
 parseTricu :: String -> [TricuAST]
 parseTricu input
   | null tokens = []
-  | otherwise = map parseSingle tokens
+  | otherwise   = map parseSingle tokens
   where
-    tokens = case lexTricu input of
-      [] -> []
-      tokens -> lines input
+    tokens
+      | null (lexTricu input) = []
+      | otherwise             = lines input
 
 parseSingle :: String -> TricuAST
-parseSingle input = case lexTricu input of
-  [] -> SEmpty
-  tokens -> case runParser parseExpression "" tokens of
-    Left err -> error $ handleParseError err
-    Right ast -> ast
+parseSingle input
+  | null tokens          = SEmpty
+  | Left  err  <- parsed = error $ handleParseError err
+  | Right ast  <- parsed = ast
+  where
+    tokens = lexTricu input
+    parsed = runParser parseExpression "" tokens
 
 parseExpression :: Parser TricuAST
 parseExpression = choice
@@ -115,10 +117,10 @@ parseTreeTerm = do
   rest <- many parseTreeLeafOrParenthesized
   pure $ foldl combine base rest
   where
-    combine acc next = case acc of
-      TLeaf -> TStem next
-      TStem t -> TFork t next
-      TFork _ _ -> TFork acc next
+    combine acc next
+      | TLeaf     <- acc = TStem next
+      | TStem t   <- acc = TFork t next
+      | TFork _ _ <- acc = TFork acc next
 
 parseTreeLeafOrParenthesized :: Parser TricuAST
 parseTreeLeafOrParenthesized = choice
@@ -181,9 +183,9 @@ parseSingleItem :: Parser TricuAST
 parseSingleItem = do
   token <- satisfy isListItem
   case token of
-    LIdentifier name -> return (SVar name)
-    LKeywordT -> return TLeaf
-    _ -> fail "Unexpected token in list item"
+    _ | LIdentifier name <- token -> return (SVar name)
+      | LKeywordT <- token        -> return TLeaf
+      | otherwise                 -> fail "Unexpected token in list item"
 
 isListItem :: LToken -> Bool
 isListItem (LIdentifier _) = True
@@ -254,9 +256,11 @@ parseTernaryFork = do
   pure $ TFork term1 term2
 
 parseTernary :: String -> Either String TricuAST
-parseTernary input = case runParser (parseTernaryTerm <* eof) "" input of
-  Left err -> Left (errorBundlePretty err)
-  Right ast -> Right ast
+parseTernary input
+  | Left err <- result  = Left (errorBundlePretty err)
+  | Right ast <- result = Right ast
+  where
+    result = runParser (parseTernaryTerm <* eof) "" input
 
 -- Error Handling
 handleParseError :: ParseErrorBundle [LToken] Void -> String