About sexp by sexp multi line editing

[xieyuheng]

I saw ketos' repl handles sexp across multi lines in the following way ::

ketos=> (+ 1 2
ketos(> 3
ketos(> (+ 4 5
ketos(> )
ketos(> )
15
ketos=>

Is it possible to use linefeed to support sexp by sexp multi line editing ? (like the repl of chez-scheme)

(see also https://github.com/kkawakam/rustyline/issues/153)

[murarth]

I want to make sure I'm understanding correctly. What I think you're proposing is this:

• When the user presses Enter, the current input buffer is checked for completeness.
  • If the input represents a complete expression, it is accepted as normal.
  • If the input is incomplete (e.g. unterminated string or unmatched parenthesis), a newline is inserted into the buffer and the user may continue editing.

Is this accurate?

[xieyuheng]

yes! for lisp sexp and string literal only.

[xieyuheng]

Maybe readline-like crate (like linefeed) is appropriate for this feature, and we need a crate like read-sexp for this ?

[xieyuheng]

If this feature is ready, it will simplify the read-sexp part of a repl.

[xieyuheng]

I have a little repl now :: https://github.com/xieyuheng/jojo/blob/master/src/repl.rs enjoy using linefeed :)

It would be great if linefeed can support the read-sexp feature, but we can live without it :P

feel free to close this issue anytime.

[murarth]

It would be outside the scope of linefeed to support this, but ketos could support this by overriding the command that executes when the user presses Enter.

I'll see what I can do.

[xieyuheng]

GREAT!

I wish I could learn from you about how to achieve this !

[murarth]

I've just pushed a commit that implements this feature.

Let me know if it works as expected or if you find any bugs.

[xieyuheng]

Thanks for doing this. It helped alot. I am closing this for now ~