Add --array

Author: chrisdone

README.md

@@ -1,4 +1,4 @@
-# jl [![Build Status](https://travis-ci.org/chrisdone/jl.svg)](https://travis-ci.org/chrisdone/jl) 
+# jl [![Build Status](https://travis-ci.org/chrisdone/jl.svg)](https://travis-ci.org/chrisdone/jl)
 jl ("JSON lambda") is a tiny functional language for querying and
 manipulating JSON.
 
@@ -81,6 +81,36 @@ programming:
 jl 'id'
 ```
 
+A sequence of JSON strings will be read in and processed individually:
+
+E.g.
+
+``` haskell
+$ cat x.json | jl id
+{"a":1}
+{"a":2}
+{"a":3}
+{"a":4}
+```
+
+If you want to read the input in as an array, use `--array`:
+
+``` haskell
+$ cat x.json | jl --array 'map _.a'
+[1,2,3,4]
+```
+
+After processing, sometimes you want to print each element of the
+array out line by line, for that use `--lines`:
+
+``` haskell
+$ cat x.json | jl --array --lines 'map _.a'
+1
+2
+3
+4
+```
+
 Taking the first element of something, using syntax that looks like
 regular array access. The `_` is a short-hand so that you don't need a
 lambda:

app/Main.hs

@@ -32,17 +32,22 @@ main :: IO ()
 main = do
   do hSetBuffering stdout LineBuffering
      hSetBuffering stdin LineBuffering
-     ((inp, file, aslines, browse, markdown, pretty), ()) <-
+     ((inp, file, inarray, aslines, browse, markdown, pretty), ()) <-
        simpleOptions
          "0.0.0"
          "jl - JSON Lambda calculus"
          "Command-line language for querying and outputting JSON."
-         ((,,,,,) <$>
+         ((,,,,,,) <$>
           strArgument
             (metavar "CODE" <>
              help "JL code; supports completion of function names" <>
              completeWith (map (\(Variable v) -> T.unpack v) (M.keys context))) <*>
           optional (strArgument (metavar "FILE")) <*>
+          flag
+            False
+            True
+            (short 'a' <> long "array" <>
+             help "Read each line of input as a single array") <*>
           flag
             False
             True
@@ -101,14 +106,21 @@ main = do
                     case Aeson.decode bytes of
                       Nothing -> hPutStr stderr "invalid input JSON"
                       Just j -> handleJson pretty expr0 aslines j
-                  Nothing -> process pretty expr0 aslines
+                  Nothing -> process pretty expr0 inarray aslines
   where
-    process pretty expr0 aslines =
+    process pretty expr0 inarray aslines =
       CB.sourceHandle stdin $= CB.lines $= conduitParserEither Aeson.value $=
-      CL.mapM_
-        (either
-           (hPutStrLn stderr . errorMessage)
-           (handleJson pretty expr0 aslines . snd)) $$
+      (if inarray
+         then do
+           es <-
+             CL.mapM (either (error . errorMessage) (return . snd)) $=
+             CL.consume
+           liftIO
+             (handleJson pretty expr0 aslines (Aeson.Array (V.fromList es)))
+         else CL.mapM_
+                (either
+                   (hPutStrLn stderr . errorMessage)
+                   (handleJson pretty expr0 aslines . snd))) $$
       CL.sinkNull
 
 -- | Handle a JSON input, printing out one to many JSON values.