give access to iterators

[videlec]

There are several useful iterators defined in PARI/GP (forperm, forprime, forqvec, ...). They are used as functions (like the standard for loops).

? forperm(3, p, print(p))
Vecsmall([1, 2, 3])
Vecsmall([1, 3, 2])
Vecsmall([2, 1, 3])
Vecsmall([2, 3, 1])
Vecsmall([3, 1, 2])
Vecsmall([3, 2, 1])

cypari2 should provide access to these as proper iterators such as

>>> for p in pari.forperm(3):
...     print(p)

Note: iterators can be recognized by the prototype character I.

[jdemeyer]

Note that GP has various different syntaxes for loops, for example:

forperm(a,p,seq)                  # Prototype: vGVI
forell(E,a,b,seq,{flag=0})        # Prototype: vVLLID0,L,
forpart(X=k,seq,{a=k},{n=k})      # Prototype: vV=GIDGDG

Implementation-wise, this difference shouldn't matter though. But it might be harder for the user to determine how to translate GP code to cypari2.

[jdemeyer]

We might want to shorten forperm to perms but there might be some name collision.

I would keep the GP name, otherwise it will just be harder to find for the user.

[jdemeyer]

I might work on this.