This is with regards to the interactive prompt.
Like sure if I want to enter a multiline expression for evaluation I could press enter. The I enter the forms first line. Then I enter subsequent ones. If I want to skip a line for clarity or some other reason I can't. Sure there is the simple workaround of inserting the ; comment symbol on that line and that's it. However that whole dynamic still feels cumbersome.
NewLISP absolutely kicks ass and is a pleasure to work with compared to Common LISP and Scheme. I think the interactive prompt should also reflect the ease of use and quality of the rest of the language. Like Common LISP is bloated and has a horrible syntax but when run in interactive mode it's a pleasure to work with. Whatever expression I enter be it an atom or list if it takes several lines so be it. Common LISP does that without complaining:
[georgiy@PANTHER ~]$ clisp -q
[1]> (+
1
1
)
2
[2]> "Hello
Lispers"
"Hello
Lispers"
[3]>
[georgiy@PANTHER ~]$
NewLISP on the other hand while workable with the clunky multiline awkwardness just isn't as pleasant as it could be to deal with:
[georgiy@PANTHER ~]$ newlisp
newLISP v.10.4.3 64-bit on Linux IPv4/6 UTF-8, execute 'newlisp -h' for more info.
> "Hello
ERR: string token too long : "Hello"
>
"Hello
Lispers"
"HellonLispers"
> (
ERR: missing parenthesis : "...( "
>
(
+
1
1
)
2
> [georgiy@PANTHER ~]$
I'm wondering can the interactive NewLISP REPL be made to be as convenient to use as a Common LISP REPL if not by default then maybe via a command line switch? Is there a reason for the current behaviour that I don't see currently?
Here's a REPL that I cobbled together. It probably has bugs, but it works pretty well for me.
(println "Quit with (exit).")
(define (input__complete? str)
(if (or (find "^s*$" str 0)
(find "^s*;[^n]*$" str 0))
true
(let (error-message ""
scanned 0)
(if
(catch
(begin
(read-expr str)
(setq scanned $0))
'error-message)
(input__complete? (slice str scanned))
(when (find {^ERR: symbol expected}
error-message 0)
(replace "(?s:^ERR: |[rn].*$)" error-message "" 0)
(throw-error error-message)
)
false))))
(let ((repl__line "")
(repl__accum '())
(repl__expression ""))
(do-while true
(unless
(catch
(begin
(when (empty? repl__accum)
(unless (= 'MAIN (context)) (print (context)))
(print ": "))
(setq repl__line (read-line))
(push repl__line repl__accum)
(setq repl__expression
(join (reverse (copy repl__accum)) "n"))
(if (input__complete? repl__expression)
(begin
(setq repl__accum '())
(setq repl__expression
(read-expr (string "(begin " repl__expression ")")))
(println (eval repl__expression)))))
'error-message)
(setq repl__accum '())
(println error-message))))
Thanks! Seems to work well.
But it broke readline capabilities.
Things i take for granted , Ctrl-A, Ctrl-E, Ctrl-P stopped working.
There should be a way to retain those features.
Readline can work with that REPL if you do the following.
1. Put William's REPL code in a file. Call it, say,
2. Invoke the REPL from the command line like this:
Readline commands (command line editing) should now work at the
Rickyboy,
Thanks for the hack.
On LINUX and BSD when compiled with GNU libreadline support a matching paren will blink on the simple or multiple newLISP command line (on same line). For this the following line:
should be put into Bash .inputrc in your $HOME directory and using a future newLISP version:
http://www.newlisp.org/downloads/development/inprogress/
Ps: will not work on OSX, only on systems with newer GNU readline libs.
Ps: if you use rlwrap, this will also enable paren matching in rlwrap, regardless of the newLISP version.
I find it hard to use in the current requirement (Multiline expressions can be entered by entering an empty line first. http://www.newlisp.org/downloads/newlisp_manual.html#multiline).
I suggest a new method:
Almost all modern Lisps (Racket, Clojure, etc.) use this method.
Racket:
> (displayln
3)
3
>
Also in Paren (My Lisp implementation): https://bitbucket.org/ktg/paren
Paren:
> (prn
3)
3
: nil
>
You can see how it works. https://bitbucket.org/ktg/paren/src/50406c0226d1bd728620a90b0c7a2d1bedb73be8/libparen.cpp?at=master#cl-906
// read-eval-print loop
void paren::repl() {
string code;
while (true) {
if (code.length() == 0) prompt(); else prompt2();
string line;
if (!getline(cin, line)) { // EOF
eval_print(code);
return;
}
code += 'n' + line;
tokenizer t(code);
t.tokenize();
if (t.unclosed <= 0) { // no unmatched parenthesis nor quotation
eval_print(code);
code = "";
}
}
}
William, the repl code broke with version 10.5.0.
: (exit)
ERR: value expected in function slice : scanned
called from user defined function input__complete?
called from user defined function input__complete?
From http://www.newlisp.org/downloads/newLISP-10.5.0-Release.html: "read-expr now uses $count instead of $0 for the number of characters processed."
Hence, William code fix(?) = change
(? == That's probably the fix, but I haven't tested it.)
You are spot on rickyboy!