2 files changed, 30 insertions, 12 deletions
diff --git a/samples/variables.sample b/samples/variables.sample
new file mode 100644
index 0000000..43d798c
--- /dev/null
+++ b/samples/variables.sample
@@ -0,0 +1,2 @@
+10 $foo !
+1 $foo @ + .
diff --git a/src/main.hs b/src/main.hs
index 90de59e..fc5d60c 100644
--- a/src/main.hs
+++ b/src/main.hs
@@ -1,6 +1,9 @@
 module Main where
 
 import Data.Char
+import Data.List (isPrefixOf)
+import Data.Map (Map, (!))
+import qualified Data.Map as M
 import System.Environment (getArgs)
 import Utils
 
@@ -10,30 +13,43 @@ getFilename (f : fs) = f
 data LWord
   = LSymbol String
   | LInteger Integer
+  | LVariable String
   deriving (Show)
 
 reprWord (LSymbol a) = a
 reprWord (LInteger a) = show a
+reprWord (LVariable a) = a
 
 parseWord rawStr
   | all isDigit rawStr = LInteger (read rawStr)
+  | "$" `isPrefixOf` rawStr = LVariable $ tail rawStr
   | otherwise = LSymbol rawStr
 
 parseSource source = source $> words .> map parseWord
 
-interpretSource :: [LWord] -> [LWord] -> IO ()
-interpretSource _ [] = putStrLn "done"
-interpretSource stack (word : rest) = do
-  newStack <- interpretWord stack word
-  interpretSource newStack rest
+interpretSource _ _ [] = putStrLn "done"
+interpretSource stack dict (word : rest) = do
+  (newStack, newDict) <- interpretWord stack dict word
+  interpretSource newStack newDict rest
 
-interpretWord :: [LWord] -> LWord -> IO [LWord]
-interpretWord stack word@(LInteger value) = pure $ word : stack
-interpretWord (a : stack) word@(LSymbol ".") = do
+-- no ops
+interpretWord stack dict word@(LInteger value) = pure (word : stack, dict)
+interpretWord stack dict word@(LVariable value) = pure (word : stack, dict)
+-- variables & printing
+interpretWord ((LVariable a) : b : stack) dict word@(LSymbol "!") =
+  let newDict = M.insert a b dict
+   in pure (stack, newDict)
+interpretWord ((LVariable a) : stack) dict word@(LSymbol "@") =
+  let lookupWord = dict ! a
+      newDict = M.delete a dict
+   in pure (lookupWord : stack, newDict)
+interpretWord (a : stack) dict word@(LSymbol ".") = do
   putStrLn $ reprWord a
-  pure stack
-interpretWord ((LInteger a) : (LInteger b) : stack) word@(LSymbol "+") = pure $ LInteger (a + b) : stack
-interpretWord _ other = error $ "[error] runtime error at " ++ show other
+  pure (stack, dict)
+-- math
+interpretWord ((LInteger a) : (LInteger b) : stack) dict word@(LSymbol "+") = pure $ (LInteger (a + b) : stack, dict)
+-- error
+interpretWord stack _ other = error $ "[error] runtime error at " ++ show other ++ "\nstack at time of error:\n" ++ show stack
 
 main :: IO ()
 main = do
@@ -45,4 +61,4 @@ main = do
   let parsed = parseSource source
   putStrLn $ "[info] parsed words:\n" ++ show parsed
   putStrLn "[info] interpreter output:"
-  interpretSource [] parsed
+  interpretSource [] M.empty parsed