use Fluture

[davidchambers]

I wrote and ran a script to verify that these changes do not change the output for a handful of projects.

[Avaq]

Approved, with some optional code style suggestions.

[Avaq]

Hey, I've known for a while that process.stdout.write is non-blocking, but I never knew it takes a callback. :)

[Avaq]

I'd probably unnest some of this by extracting pieces:

Suggested change

	// parseFile :: Options -> String -> Future Error String
	const parseFile = options => filename => (
	map (promap (lines)
	(unlines)
	(B (snd)
	(reduce (flip (line =>
	pair (num => B (Pair (num + 1))
	(append (parseLine (options)
	(filename)
	(num)
	(line))))))
	(Pair (1) ([])))))
	(readFile (filename))
	);
	// overLines :: (Array String -> Array String) -> String -> String
	const overLines = promap (lines) (unlines);
	// parseFile :: Options -> String -> Future Error String
	const parseFile = options => filename => {
	const parse = parseLine = (options) (filename);
	const reducer = line => pair (num => B (Pair (num + 1))
	(append (parse (num) (line))));
	const parseLines = B (snd) (reduce (flip (reducer)) (Pair (1) ([])));
	return T (readFile (filename)) (map (overLines (parseLines)));
	};

[Avaq]

You could use thrush as a poor-man's pipe operator to make the data flow and indentation a bit more natural.

Suggested change

	(chain (output =>
	program.insertInto == null ?
	writeStdOut (output) :
	chain (writeFile (program.insertInto))
	(map (replace (delimiters) ('$1\n\n' + output + '\n$2'))
	(readFile (program.insertInto))))
	(transcribe (options) (program.args)));
	(T (transcribe (options) (program.args))
	(chain (output =>
	program.insertInto == null ?
	writeStdOut (output) :
	chain (writeFile (program.insertInto))
	(map (replace (delimiters) ('$1\n\n' + output + '\n$2'))
	(readFile (program.insertInto))))));

[Avaq]

You know what the type of the thing your Future will reject with is, so you may not need the string cast.

Suggested change

	(e => { console.error (String (e)); process.exit (1); })
	(_ => { process.exit (0); })
	(e => { console.error (e.stack); process.exit (1); })
	(_ => { process.exit (0); })