A lisp oriented question - interning symbols for use in Maxima

Am Sonntag, den 18.10.2009, 19:12 +0200 schrieb ?iga Lenar?i?:
> Hi!
> 
> I'm writing a Maxima interface to CFFI (for using C libraries from  
> Maxima).
> 
> I have the following problem - I want to convert a lisp string into a  
> symbol representing a Maxima function which would be invoked by the  
> same 'string' from Maxima console.
> 
> Right now I use
> 
> (intern (concatenate 'string "$" string))
> 
> to get the symbol which should represent the maxima function.
> 
> I get the correct results for cases such as "HelloWorld" -> | 
> $HelloWorld| (then the function can be called from maxima with  
> 'HelloWorld()').
> 
> However if I try non-mixed case strings I get an inverted result. So  
> a string like "mul2" gives me a symbol |$MUL2|, which from Maxima is  
> seen as 'MUL2' and not 'mul2' as I would want it to be.
> 
> What should I do to get the correct lisp symbol, so calling from  
> Maxima will look like the string I use?
> 
> Are there already any functions in Maxima I should use or how should  
> I roll my own?
> 
> 
> On a side note, is there any interest for a foreign library interface  
> in Maxima? Of course it works only in CFFI supported lisps, so no GCL  
> support, sorry. I quickly compared the calling overhead by importing  
> the C function 'rand()' from 'libc' and compared it to Maxima's  
> function 'random' - calling C function from Maxima was faster, so I  
> guess the overhead is quite small (on SBCL at least).

The functions which handle Maxima's convention of inverting strings are:

  maybe-invert-string-case 
  intern-invert-case
  print-invert-case

maybe-invert-string-case accepts a string and returns a string, which is
inverted, if all characters are upper case or lower case.

Examples:

 (maybe-invert-string-case "example") --> "EXAMPLE"
 (maybe-invert-string-case "EXAMPLE") --> "example"
 (maybe-invert-string-case "Example") --> "Example"

intern-invert-case accepts strings too, but interns the converted string
in the package :maxima. This function is equivalent to 
  (intern (maybe-invert-string-case str))

Examples:

  (intern-invert-case "text") --> TEXT :INTERNAL
  (intern-invert-case "TEXT") --> |text| NIL
  (intern-invert-case "Text") --> |Text| NIL

print-invert-case accepts symbols as input and returns an inverted
string. The routines accepts strings and any other printable values too,
but returns strings unchanged.

Examples:

  (print-invert-case 'text)  --> "text"
  (print-invert-case '|text| --> "TEXT"

  (print-invert-case "TEXT"  --> "TEXT"
  (print-invert-case 10.0)   --> "10.0"

Dieter Kaiser