Eli Barzilay wrote on 12/02/2014 09:31 PM:
On Tue, Nov 25, 2014 at 1:29 PM, Leif Andersen <l...@leifandersen.net> wrote:
Just to clarify a bit, we were more thinking of extending the default
repl to have line editing features, rather then making xrepl the
default,
If you're talking about implementing line editing yourself, then my
personal reaction to that would be "wonderful", but doing it properly is
something that is difficult and easy to underestimate....
I agree fully with Eli.
Also, separate from practical benefit of having basic `readline`-like
line editing in pure Racket, you could go gratuitously coolness factor
on this. For example, I don't think I've seen a non-full-screen
character-terminal REPL do syntax coloring, matching paren highlighting,
and full up/down cursor navigation within a single REPL input. That's
labor-of-love coolness, and all who behold it will respect your name.
("http://www.neilvandyke.org/racket-charterm/"; would help with some
primitives and device portability, but you'd still have to layer a lot
of work atop that. Offhand, the most nonobvious tricky part I can think
of is not getting program confused about where text and your cursor are
on the screen. Different terminals will have different behavior when
cursor is in the last column, or cursor is in the last row and column,
or you're inserting/deleting characters or lines (which some terminals
will support differently, and others not at all). You also have to
decide how you want to handle the user experience of some kind of Ctrl-L
redraw, since terminal screens get corrupted often by text written by
other processes, Ctrl-L also helps mitigate terminal quirks you don't
yet handle, and terminal-savvy people will expect a Ctrl-L. It's
possible to make a self-healing character terminal display, on those
terminals that permit reading screen addresses and that have sufficient
idle bandwidth, but I haven't heard of anyone doing that yet, and
everyone just has a Ctrl-L.)
Neil V.
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