On Friday, August 12, 2016 at 6:36:31 PM UTC+1, Waldek Hebisch wrote:
>
> Martin R wrote:
> >
> > given the continued interest in some features of fricas from some sage
> > users, I had a look at the fricas interface in sage, and I'm thinking of
> > improving it.
> >
> > The main question is: how can sage receive the output from fricas?
> >
> > currently, sage essentially sends "unparse(result:InputForm)" to fricas,
> > and then parses the output: it strips away the prompt and the step
> number
> > and it looks for the type information, all using regular expressions.
> >
> > a first improvement I was thinking of is to use the ioHook to separate
> the
> > algebra output from the remaining information. however, at least the
> step
> > number appearing just before the algebra output is currently not
> decorated.
> >
> > is there a better way to get the results of computations - and also to
> send
> > instructions to fricas?
>
> There are many ways. Some issues were discussed few years
> ago when Serge D. Mechveliani tried to create interface
> between FriCAS and Haskell.
>
> I suspect that you want to do little improvement as opposed
> to major rewrite, so some ideas that _may_ be easy:
>
> - using S-expressions to communicate with FriCAS. On FriCAS
> side it is quite easy to generate textual form of S-expressions.
> S-expressions were designed to be easy to parse, so handling
> them on Python side should be easy too
> - as Dima wrote Sage interface to Maxima works by putting Maxima
> in the same process as Sage. This should be possible with
> FriCAS too. I just checked that using Maxima build on to
> of sbcl and 'load-fricas.lisp' both FriCAS and Maxima seem
> to work in single process. So it seems that small adjustment
> to build system should be enough
>
> as far as the latter is concerned, most of the needed code is already in
Sage;
namely, src/sage/interfaces/maxima_lib.py is basically an example of
running Maxima in ECL,
which is embedded in Python; for the latter the code is in
src/sage/libs/ecl.pyx
In the latter one sees an example of calling CL functions from Sage:
sage: from sage.libs.ecl import *
sage: ecl_eval("(defun fibo (n)(cond((= n 0) 0)((= n 1) 1)(T (+
(fibo (- n 1)) (fibo (- n 2))))))")
<ECL: FIBO>
sage: ecl_eval("(mapcar 'fibo '(1 2 3 4 5 6 7))")
<ECL: (1 1 2 3 5 8 13)>
That is, one would just need to adapt src/sage/interfaces/maxima_lib.py to
loading/running FriCAS instead.
For this one needs to know some parts of FriCAS, that is, how to load it in
a running CL instance, etc etc...
Dima
> --
> Waldek Hebisch
>
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