Adding 'it' and 'itN' for execution count N variables

IHaskell · Nov 11, 2013 · ab5b30e · ab5b30e
1 parent e02e5c2
commit ab5b30e
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Showing 3 changed files with 78 additions and 14 deletions.
diff --git a/Haskell-Notebook.ipynb b/Haskell-Notebook.ipynb
@@ -224,20 +224,71 @@
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "doubleIt \"hello\""
+      "1+1"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "metadata": {},
+       "output_type": "pyout",
+       "prompt_number": 1,
+       "text": [
+        "2\n"
+       ]
+      },
+      {
+       "metadata": {},
+       "output_type": "display_data"
+      }
+     ],
+     "prompt_number": 1
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "it * 2"
      ],
      "language": "python",
      "metadata": {},
      "outputs": [
       {
        "html": [
-        "<span style='color: red; font-style: italic;'>Couldn't match expected type `Int'<br/>            with actual type `String'<br/></span>"
+        "<span style='color: red; font-style: italic;'>No instance for (GHC.Num.Num ()) arising from a use of `GHC.Num.*'<br/>Possible fix: add an instance declaration for (GHC.Num.Num ())<br/></span>"
        ],
        "metadata": {},
        "output_type": "display_data"
       }
      ],
-     "prompt_number": 7
+     "prompt_number": 2
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "Out[1] * 2"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "html": [
+        "<span style='color: red; font-style: italic;'>Not in scope: data constructor `Out'<br/></span>"
+       ],
+       "metadata": {},
+       "output_type": "display_data"
+      }
+     ],
+     "prompt_number": 3
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
     }
    ],
    "metadata": {}

diff --git a/IHaskell/Eval/Evaluate.hs b/IHaskell/Eval/Evaluate.hs
@@ -46,19 +46,24 @@ makeWrapperStmts = (fileName, initStmts, postStmts)
     randStr = "1345964344725219474" :: String
     fileVariable = "file_var_" ++ randStr
     oldVariable = fileVariable ++ "_old"
+    itVariable = "it_var_" ++ randStr
     fileName = ".ihaskell_capture"
 
-    postStmts :: [String]
-    postStmts = [
-            "hFlush stdout",
-      printf "hDuplicateTo %s stdout" oldVariable,
-      printf "hClose %s" fileVariable]
-
     initStmts :: [String]
     initStmts = [
+      printf "let %s = it" itVariable,
       printf "%s <- openFile \"%s\" WriteMode" fileVariable fileName,
       printf "%s <- hDuplicate stdout" oldVariable,
-      printf "hDuplicateTo %s stdout" fileVariable]
+      printf "hDuplicateTo %s stdout" fileVariable,
+      printf "let it = %s" itVariable]
+
+    postStmts :: [String]
+    postStmts = [
+      printf "let %s = it" itVariable,
+      "hFlush stdout",
+      printf "hDuplicateTo %s stdout" oldVariable,
+      printf "hClose %s" fileVariable,
+      printf "let it = %s" itVariable]
 
 write :: GhcMonad m => String -> m ()
 write x = when debug $ liftIO $ hPutStrLn stderr x
@@ -101,15 +106,21 @@ interpret action = runGhc (Just libdir) $ do
   imports <- mapM parseImportDecl globalImports
   setContext $ map IIDecl imports
 
+  -- Give a value for `it`. This is required due to the way we handle `it`
+  -- in the wrapper statements - if it doesn't exist, the first statement
+  -- will fail.
+  runStmt "()" RunToCompletion
+
   -- Run the rest of the interpreter
   action
 
 -- | Evaluate some IPython input code.
-evaluate :: String                    -- ^ Haskell code or other interpreter commands.
+evaluate :: Int                       -- ^ The execution counter of this evaluation.
+         -> String                    -- ^ Haskell code or other interpreter commands.
          -> Interpreter [DisplayData] -- ^ All of the output.
-evaluate code
+evaluate execCount code
   | strip code == "" = return [] 
-  | otherwise = joinDisplays <$> runUntilFailure (parseCommands $ strip code)
+  | otherwise = joinDisplays <$> runUntilFailure (parseCommands (strip code) ++ [storeItCommand execCount])
   where
     runUntilFailure :: [Command] -> Interpreter [DisplayData]
     runUntilFailure [] = return []
@@ -121,6 +132,8 @@ evaluate code
           return $ result ++ restRes
         Failure -> return result
 
+    storeItCommand execCount = Statement $ printf "let it%d = it" execCount
+
 joinDisplays :: [DisplayData] -> [DisplayData]
 joinDisplays displays = 
   let isPlain (Display mime _) = (mime == PlainText)

diff --git a/Main.hs b/Main.hs
@@ -143,7 +143,7 @@ replyTo interface ExecuteRequest{ getCode = code } replyHeader state = do
   send $ PublishStatus busyHeader Busy
 
   -- Get display data outputs of evaluating the code.
-  outputs <- evaluate $ Chars.unpack code
+  outputs <- evaluate execCount $ Chars.unpack code
 
   -- Find all the plain text outputs.
   -- Send plain text output via an output message, because we are just