From 9f8e83010903509d338722c4a2adef295e8ea67e Mon Sep 17 00:00:00 2001
From: Gregor Kleen <gkleen@yggdrasil.li>
Date: Mon, 22 Feb 2016 14:46:02 +0000
Subject: Query for formula indefinetly

---
 rpn.hs | 28 +++++++++++++++-------------
 1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/rpn.hs b/rpn.hs
index dbb0f1f..68c0831 100755
--- a/rpn.hs
+++ b/rpn.hs
@@ -1,4 +1,6 @@
-import Control.Monad (join, sequence)
+#!/usr/bin/env runghc
+
+import Control.Monad (join, sequence, forever)
 import System.Environment (getArgs)
 import Data.Maybe (listToMaybe, isJust)
 import Data.Char (isSpace)
@@ -39,25 +41,25 @@ fromSymbol _ = (0, 0)
 
 
 pPrint :: Show a => Symbol a -> String
-pPrint (Number x d) = (show x) ++ " ± " ++ (show d)
+pPrint (Number x d) = (show x) ++ " ± " ++ (show d) ++ " (relative error: " ++ (show $ d / x) ++ ")"
 pPrint s = show s
 
 main :: IO ()
 main = do
   hSetBuffering stdin LineBuffering
   hSetBuffering stdout NoBuffering
-  (mode:args) <- getArgs
-  let symbols = join . join $ map (map words) . map lines $ args
+  forever $ do
+    putStr "Formula: "
+    line <- getLine
+    let --symbols = join . join $ map (map words) . map lines $ args
+      symbols = words line
       unknownSymbols = nub $ filter (not . isKnownSymbol) symbols
-  symbolMap <- sequence $ map (sequencePair . (\x -> (x, clarifySymbol x))) unknownSymbols
-  let symbolMap' = M.fromList symbolMap
-      symbols' = map (\x -> if x `elem` (M.keys symbolMap') then symbolMap' M.! x else [x]) symbols
-      symbols'' = map interpreteSymbol $ join symbols'
-  let result = evalExpVec symbols''
-  case mode of
-    "n" -> putStrLn . show . fst $ fromSymbol result
-    "e" -> putStrLn . show . snd $ fromSymbol result
-    _ -> putStrLn $ pPrint result
+    symbolMap <- sequence $ map (sequencePair . (\x -> (x, clarifySymbol x))) unknownSymbols
+    let symbolMap' = M.fromList symbolMap
+        symbols' = map (\x -> if x `elem` (M.keys symbolMap') then symbolMap' M.! x else [x]) symbols
+        symbols'' = map interpreteSymbol $ join symbols'
+    let result = evalExpVec symbols''
+    putStrLn . pPrint $ evalExpVec symbols''
 
 clarifySymbol :: String -> IO [String]
 clarifySymbol s = do
-- 
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