On Thursday, 14 May 2015 at 10:18:13 UTC, Maxim Fomin wrote:
On Thursday, 14 May 2015 at 09:53:20 UTC, Per Nordlöw wrote:
At
https://github.com/nordlow/justd/blob/master/algorithm_ex.d#L43
I've implemented a function either() with behaviour similar to
the `or` function/operator in dynamic languages such as Python
and Lisp.
I'm almost satisified with it except that the lazy evaluation
at
https://github.com/nordlow/justd/blob/master/algorithm_ex.d#L45
cannot be made nothrow.
If I qualify the function as nothrow DMD complains as
algorithm_ex.d(45,16): Error: 'a' is not nothrow
algorithm_ex.d(46,29): Error: '_param_1' is not nothrow
I don't see a reason why any of these two cases should throw.
Lazy argument is essentially delegate/function. Currently there
is no
way to mark it as nothrow.
The same problem occurs if I make the implementation use only
one function and check the recursion termination case with
`static if (bs.length == 1)` instead.
Is there a workaround for this?
One way to address is to use delegate explicitly.
int foo(lazy int a) //nothrow
{
return a;
}
int bar(int delegate() nothrow dg) nothrow
{
return dg();
}
void main() nothrow
{
int a;
bar(()=>a);
}
That does not feel right at all. D's filosophy is to infer these
things.Are you saying that I should create to overloads for the
leaf case of either(), namely one that takes a nothrow delegate
as argument and another overload that handles the throw case.
Further you example functions are not templates. either() must be
a template. Could you please show how to modify either() to use
your delegate-version instead.
