Re: "to" vs "method"

On Apr 3, 2010, at 5:06, Thomas Leonard wrote:

> I just discovered that there are two ways of defining a method in E:
>
> def foo1 {
> 	to run() { return 3 }
> }
>
> def foo2 {
> 	method run() { 3 }
> }

Yes. 'method' is intended as the 'internal' Kernel-E definition which  
doesn't magically bind any nouns. (For example, the expansion of fn {}  
does not use 'to'-equivalent.)

> Interestingly, calling foo2() is between 3 and 10 times faster than
> calling foo1(), depending on how deeply nested the call is:
> ...
> I guess this is because "to" uses __return, which is implemented by
> throwing an exception in Java (so speed depends on the size of the
> stack).

Yes. Of course, an optimizing implementation should be able to  
eliminate this cost, either by recognizing that no nonlocal exit is  
necessary (the just-returning-a-value case) or by compiling simple  
cases into a cheap jump.

E-on-CL does both (well, the latter provided the underlying CL  
cooperates).

-- 
Kevin Reid                                  <http://switchb.org/kpreid/>