Required ATL transform's keyword-only parameter can't be curryfied

[Gouvernathor]

transform al(child, b, *, c, d=5):
    pass

al(b=5) works, and returns a (sort-of) curryfied version of al (sort-of because al(b=5)(b=3) works)
al(d=6) works and does (sort-of) the same
al(c=5) fails, for no apparent reason.

This is because the related section of atl.py was written when defaultless (=required) keyword-only arguments weren't a thing, and it wasn't updated in 13 years when Andy upgraded the parameters syntax to py3 standards.

This should/will be fixed when upgrading the parameters system to using the inspect module.

Also, atl doesn't take *args or **kwargs (the parser checks against it), and I'm not sure why.

[Gouvernathor]

Unbound required keyword-only parameters are also forgotten when currying the transform : al(b=7) has an equivalent signature of (child, b=7, d=6). Not only has the star been omitted (d is now positional-or-keyword, instead of keyword-only), but c has simply vanished.

[Gouvernathor]

pos-only arguments (placed before a slash in the signature) are parsed and compiled correctly, but are treated as pos-or-keyword by the atl code and turned into that in the curryfied version. For transform t(a, /, b), t(a=1) and t(b=5)(a=1) will work when they're supposed to fail.

[Gouvernathor]

Maybe this deserves a separate issue, because it has to do with child is managed.

transform h(a, child, b=5):
    pass

h(child=Null()).child is None. The Null() has been passed to the child variable in the ATL block's namespace, but it was not set to be the child attribute of the resulting transform (it or a duplicated version, whatever).
One could argue that it makes sense, if the creator added a child parameter, to trust them with it hands-off. I'd note that when calling h(1, Null()) the attribute does get set, so it's still a discrepancy, but ok. What's actually a problem, is that it breaks At.
At(Null(), h) returns that same child-less transform. chil != At(chil, t).child should be an invariant, and here that invariant is broken.