Implemented from blog

1 files changed, 18 insertions, 21 deletions

diff --git a/src/Lib.hs b/src/Lib.hs
index 5d58008..698c0ae 100644
--- a/src/Lib.hs
+++ b/src/Lib.hs
@@ -1,13 +1,15 @@
 {-# LANGUAGE LambdaCase #-}
 
 module Lib
-  ( fromJotter
+  ( fromJottary
+  , s
+  , k
+  , i
   ) where
 
+import           Control.Monad                  ( replicateM )
+import           Debug.Trace                    ( trace )
 import           Term
-import           Utils
-
-data State = L | R
 
 s :: Term
 s = Abs (Abs (Abs (App (App (Idx 2) (Idx 0)) (App (Idx 1) (Idx 0)))))
@@ -18,22 +20,17 @@ k = Abs (Abs (Idx 1))
 i :: Term
 i = Abs (Idx 0)
 
-clean :: String -> String
-clean (x : xs) | x == '0' || x == '1' = x : clean xs
-               | otherwise            = clean xs
-clean [] = []
+count :: String -> Int
+count (x : xs) | x == '1'  = 1 + count xs
+               | otherwise = count xs
+count [] = 0
 
--- reverse wouldn't be needed if [0F] instead of [F0]
-fromCleanJotter :: String -> Term
-fromCleanJotter t | even $ length t = go L $ reverse t
-                  | otherwise       = go R $ reverse t
+fromDecimalJottary :: Int -> Term
+fromDecimalJottary p = foldr1 App (reverse (gen !! p) ++ [i])
  where
-  go L ('0' : xs) = App s (go R xs)
-  go R ('0' : xs) = App (go L xs) s
-  go L ('1' : xs) = App k (go R xs)
-  go R ('1' : xs) = App (go L xs) k
-  go _ []         = i
-  go _ _          = invalid
-
-fromJotter :: String -> Term
-fromJotter = fromCleanJotter . clean
+  lio = Abs (App (App (Idx 0) s) k)
+  rio = Abs (App s (App k (Idx 0)))
+  gen = [0 ..] >>= (`replicateM` [lio, rio])
+
+fromJottary :: String -> Term
+fromJottary t = trace (show $ count t) (fromDecimalJottary $ count t)