Ergonomic language features and lib cleanup

+ let bindings
+ where bindings
+ do notation

I explored enough of the alternative language design space and decided
that we should commit fully to Lambda style. That means no more highly
tacit/concatenative point-free/partial programs as default. We'll keep
taking advantage of those capabilities when it makes sense, but the
library will continue to see massive overhauls.

src/REPL.hs

@@ -130,15 +130,15 @@ repl = do
 
     handleOutput :: REPLState -> InputT IO ()
     handleOutput state = do
-      let formats = [Decode, Tree, FSL, AST, Ternary, Ascii]
+      let formats = [Decode, Tree, FSL, AST, Ternary, Ascii, Number, StringLit]
       outputStrLn "Available output formats:"
       mapM_ (\(i, f) -> outputStrLn $ show (i :: Int) ++ ". " ++ show f)
         (zip [1..] formats)
 
       evalResult <- runMaybeT $ do
-        input <- MaybeT $ getInputLine "Select output format (1-6) < "
+        input <- MaybeT $ getInputLine "Select output format (1-8) < "
         case reads input of
-          [(n, "")] | n >= 1 && n <= 6 ->
+          [(n, "")] | n >= 1 && n <= 8 ->
             return $ formats !! (n-1)
           _ -> MaybeT $ return Nothing