On 4/10/06, Guido van Rossum <[EMAIL PROTECTED]> wrote:
> The only syntax that is acceptable to me ... would look like
> def fn(a: Seq, b: Index, c: Text = "default"): ...
> where Seq, Index and Text can be expressions (the main problem with
> the syntax you propose is that the type can't be much more than an
> identifier before it gets ambiguous or unreadable).
I agree that putting the identifier after the type (and wrapping to
one parameter per line) allows for a longer expression.
On the other hand, it also allows for a *much* longer expression,
which becomes unreadable anyhow. Whether this would be enough of a
problem in practice to justify requiring identifiers ... I'm not sure.
Maybe the actual usage of conditional expressions will help answer
that.
> A completely separate issue is what kind of objects Seq, Index and
> Text would be; but that's a discussion we have separate from the
> syntactic discussion.
What do you mean? The only question that leaps out at me is whether
they should be predicates or constructors. In other words, should
def f(a:Seq): ...
mean something closer to
def f(a):
assert Seq(a)
...
or
def f(a):
a=Seq(a)
...
If adaptation is light enough to be useful, then I can't see any
reason to prefer the first.
def f(a:0<a<10): ...
isn't *that* much cleaner than whichever of
def f(a:clip_to_int_range(0,10)): ...
def f(a:int_in_range(0,10)): ...
def f(a:clip_to_number_range(0,10)): ...
def f(a:number_in_range(0,10)): ...
was actually intended.
-jJ
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