So I was thinking about a "killer feature" for a text editor. Wouldn't it be neat if you could expand function calls into their definitions, in-place? For example, suppose we have "minus" defined like so, somewhere in another file:
minus (a, b, c) (x, y, z) = (a - x, b - y, c - z)
Later, we make use of the function in our current context:
let p1 = (1, 2, 3) p2 = (4, 5, 6) in p1 `minus` p2
By telling the editor to "expand" the minus, we get a temporary replacing of the above with:
(1 - 4, 2 - 5, 3 - 6)
Another example:
parse s = map readLine ls
And supposing that readLine is defined somewhere else, moving the cursor to readLine in the line above and "expanding" becomes:
parse s = map (\line -> words $ dropWhile (== ' ') line)
This is all pretty standard for the kinds of things we do in Haskell to work it out by hand, but is there any reason the parser couldn't do this? I think it would be even harder to do automatically in any other language. Maybe it's already been attempted or done? Curious, Duane Johnson