3 files changed, 23 insertions, 2 deletions
diff --git a/src/Eval.hs b/src/Eval.hs
index 276524c..331ab8d 100644
--- a/src/Eval.hs
+++ b/src/Eval.hs
@@ -17,6 +17,7 @@ import           Helper
 import           Parser
 import           Paths_bruijn
 import           Reducer
+import           System.Clock
 import           System.Console.Haskeline
 import           System.Directory
 import           System.Environment
@@ -284,6 +285,19 @@ evalInstruction (ContextualInstruction instr inp) s@(EnvState env conf _) rec =
       yeet s' (c : cs') = do
         s'' <- s'
         yeet (evalCommand inp s'' c) cs'
+    Time e -> do
+      start <- getTime Monotonic
+      _     <- evalInstruction (ContextualInstruction (Evaluate e) inp) s rec
+      end   <- getTime Monotonic
+      let roundSecs x =
+            (fromIntegral (round $ x * 1e6 :: Integer)) / 1e6 :: Double
+      putStr
+        $ show
+        $ roundSecs
+        $ (fromIntegral $ toNanoSecs $ diffTimeSpec start end :: Double)
+        / 1e9
+      putStrLn " seconds"
+      rec s
     _ -> rec s
 evalInstruction instr s rec =
   evalInstruction (ContextualInstruction instr "<unknown>") s rec
diff --git a/src/Helper.hs b/src/Helper.hs
index 98cdaea..97de641 100644
--- a/src/Helper.hs
+++ b/src/Helper.hs
@@ -138,7 +138,7 @@ instance Show Expression where
   show (Prefix p e) = show p <> " " <> show e
 data Command = Input String | Import String String | Test Expression Expression
   deriving (Show)
-data Instruction = Define Identifier Expression [Instruction] | Evaluate Expression | Comment | Commands [Command] | ContextualInstruction Instruction String
+data Instruction = Define Identifier Expression [Instruction] | Evaluate Expression | Time Expression | Comment | Commands [Command] | ContextualInstruction Instruction String
   deriving (Show)
 
 data EvalConf = EvalConf
diff --git a/src/Parser.hs b/src/Parser.hs
index 676bf37..92c33df 100644
--- a/src/Parser.hs
+++ b/src/Parser.hs
@@ -265,12 +265,18 @@ parseComment = do
   _ <- some $ noneOf "\r\n"
   return ()
 
+parseTime :: Parser Instruction
+parseTime = do
+  _ <- string ":time" <* sc <?> "time instruction"
+  e <- parseExpression
+  pure $ Time e
+
 parseImport :: Parser Command
 parseImport = do
   _    <- string ":import" <* sc <?> "import instruction"
   path <- importPath
   ns   <- (try $ sc *> (namespace <|> string ".")) <|> (eof >> return "")
-  pure (Import (path ++ ".bruijn") ns)
+  pure $ Import (path ++ ".bruijn") ns
 
 parseInput :: Parser Command
 parseInput = do
@@ -318,4 +324,5 @@ parseReplLine =
     <|> ((Commands . (: [])) <$> (try parseTest))
     <|> ((Commands . (: [])) <$> (try parseInput))
     <|> ((Commands . (: [])) <$> (try parseImport))
+    <|> try parseTime
     <|> try parseEvaluate