Hi Andras, > I would like to ask some questions on Pil21 features. > It is enough if you points to some examples where I could dig into the > details...
These are indeed very good questions! Thanks that you ask, they need to be clarified. > - What is special in the ‘priv’ namespace handling? > pil64 used it to store (private) symbols. I noticed that the way pil64 implemented the 'private' function was not good. It created a normal namespace 'priv' on-the-fly, interned the given symbols into that namespace, and then put 'priv' as the *second* namespace in the search order: : (private) foo # Intern 'foo' in 'priv' : (symbols) # Search order -> (pico priv) So now 'foo' is indeed private. The problem is that *if' another symbol named "foo" exists in 'pico', it overshadoes the 'foo' in 'priv', and this is not what is expected for a private symbol. Pil21 implements a special handling for 'priv'. Now 'priv' is part of the interpreter core, and behaves a little different from normal namespaces. : (private) foo # Intern 'foo' in 'priv' : (symbols) # Search order -> (pico) : (all 'priv) -> (priv~foo) 'priv' is not put into the search order at all, but internally it is always searched first. That way it will not be overridden by symbols with the same names in 'pico', but still *new* symbols will be interned in 'pico'. > - What is the purpose of the ‘~’ marker in the namespaces? This is only used for error checking: To check in 'symbols' that the arguments are really namespaces, and that 'nsp' in 'nsp~foo' is OK. > - What does it mean, that map functions accept atomic arguments? > It is not required to pass lists as arguments? > Atomic arguments are handled as 1-item lists or infinite lists with the > same item? Yes, the latter. In pil32 and pil64 you could call : (mapcar * (1 2 3 4 5 6) (2 .)) -> (2 4 6 8 10 12) i.e. supply an infinite list of 2's. Now in pil21 you can simply call : (mapcar * (1 2 3 4 5 6) 2) This is especially useful if '2' is not a constant, e.g. (mapcar * Lst Factor) In pil64 you would need to build the circular list explicitly: (mapcar * Lst (circ Factor)) ☺/ A!ex -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
