Hi Vincent,
On 2018-09-30, Vincent Delecroix <20100.delecr...@gmail.com> wrote:
> The main problem is that G is a gap group and not a libgap
> group. By gap group I mean that the interface going through
> the pexpect interface. The two systems gap and libgap do not
> seem to share the namespaces (which make sense).
Oops. You are right. After correcting it, my example works just fine.
Sorry for that.
Nonetheless, I have a wishlist concerning libgap:
A) Generator access with dot syntax
I'd like to have that G.1 returns the first generator of the
group (which it does in GAP language, but neither in the gap pexpect
interface nor in libgap).
-------
B) Optional values for libGAP functions
In Gap, it is possible to create functions with
optional arguments. I have a function in Gap whose definition starts
like that:
regularPermutationAction := function(G)
local gens, N, S, L, gg, forceDefiningGenerators;
forceDefiningGenerators := ValueOption("forceDefiningGenerators");
...
In GAP syntax, having a group G, I would call the function as follows:
P := regularPermutationAction(G: forceDefiningGenerators);;
How would I call it when G is defined in libgap?
G.regularPermutationAction(forceDefiningGenerators=True)
doesn't work.
--------
C) Make it possible to refer to an libgap object in a command string
In gap (the pexpect interface), in the example from B), I'd do
P = gap('regularPermutationAction({}:
forceDefiningGenerators)'.format(G.name()))
and in the example from A), I'd do
gap('{}.1'.format(G.name()))
but libgap objects apparently have no name by which they are known in
the libgap interpreter.
-------
D) libgap's and gap's methods should have roughly similar semantics
It is really unfortunate that it hasn't been attempted
to keep libgap as close to the pexpect interface as possible. For
example:
1. sage: libgap('SymmetricGroup(8)')
"SymmetricGroup(8)"
sage: type(_)
<type 'sage.libs.gap.element.GapElement_String'>
sage: gap.eval('SymmetricGroup(8)')
'Sym( [ 1 .. 8 ] )'
sage: type(_)
<type 'str'>
In other words, libgap() behaves roughly like gap.eval()
2. sage: libgap.eval('SymmetricGroup(8)')
Sym( [ 1 .. 8 ] )
sage: gap('SymmetricGroup(8)')
SymmetricGroup( [ 1 .. 8 ] )
In other words, libgap.eval() behaves roughly like gap()
Best regards,
Simon
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