To read an expression from a file or string?

Cyril · Post by **Cyril** » Thu Feb 07, 2008 1:54 am

I feel myself dumb (as usual), but is it a way to read an newlisp expression from file or string (buffer), not evaluating it? Something like read in both Common Lisp and Scheme?

Jeff · Post by **Jeff** » Thu Feb 07, 2008 2:24 am

read-file

Cyril · Post by **Cyril** » Thu Feb 07, 2008 3:34 am

Jeff wrote:read-file

read-file reads file as a string, not as an expression. I mean, if you file contains a line "(a b c)", or you have a string with the same content, how do you read or convert it to the list (a b c) ?

HPW · Post by **HPW** » Thu Feb 07, 2008 6:29 am

Code: Select all

> (eval-string "'(a b c)")
(a b c)

But so you have the same as a 'load'.

Jeff · Post by **Jeff** » Thu Feb 07, 2008 12:44 pm

Ah, you want to read the string in as a quoted expression. No, not that I know of. Anything that would interpret the block would evaluate it.

Dmi · Post by **Dmi** » Thu Feb 07, 2008 1:25 pm

Hi, Cyrill!

Look into http://en.feautec.pp.ru around newlisp console (nlc) project. There is some sort of a parser. Feel free to ask questions.

P.S. But, I think it would be cool to have a newlisp hardcoded engine (I suspect - a link to some existing internal function will be sufficient ;-)

Lutz · Post by **Lutz** » Thu Feb 07, 2008 2:23 pm

Internally such a function already exists. It reads one top-level term or s-expression from a file or string and returns. It would be easy to expose this function in the newLISP API.

The question is: what do you want to do with it? Perhaps there is a different way to achieve the same?

Lutz

Dmi · Post by **Dmi** » Thu Feb 07, 2008 2:35 pm

Hi, Lutz!

My needs was: code analyze/edit, reformat/reindent, sanitize (wrapping the string with (quote ) before eval-string is not a way in common).

What about Cyrill?

Jeff · Post by **Jeff** » Thu Feb 07, 2008 3:11 pm

I would definitely like access to that, too, Lutz. There are dozens of uses. Writing newnewLISP, for example :)

m35 · Post by **m35** » Thu Feb 07, 2008 5:57 pm

I wanted to do the same thing for the 'newLINT' idea--load a .lsp file as a list instead of executing it. Long after I gave up on making it, it occurred to me that perhaps doing

Code: Select all

(eval-string (append "(quote " (read-file "file.lsp") ")"))

might do the trick. I never actually tested it though.

Cyril · Post by **Cyril** » Thu Feb 07, 2008 10:37 pm

Dmi wrote:My needs was: code analyze/edit, reformat/reindent, sanitize (wrapping the string with (quote ) before eval-string is not a way in common).

What about Cyrill?

In fact the same: any processing of the newLISP programs in newLISP itself. My idea was to implement some experimental preprocessor: that one was probably not worth doing, but there are others.