• Michael (17/17) Oct 16 2012 Hello!
• Adam D. Ruppe (9/11) Oct 16 2012 The problem is that UFCS only works on functions in the global
• Jonathan M Davis (5/20) Oct 16 2012 That seems like it goes against the whole "turtles all the way down" pri...
• Michael (6/28) Oct 18 2012 Thank you guys. I can't believe that haven't thought of that.

"Michael" <pongad gmail.com> writes:

Hello!
   I have been using D for a while, but only recently paid 
attention to UFCS. For some reason, I can't convince my code to 
compile properly:

void main() {
	import std.range, std.stdio;
	
	auto sqrs = sequence!((a,n) => n*n)(0);
	auto fibs = recurrence!((a,n) => a[n-1]+a[n-2])(1, 1);
	foreach (v; zip(sqrs, fibs).take(10)) writeln(v);
}

The compiler complains about "undefined identifier 'take'". If I 
rewrite the last line to "take(zip(sqrts, fibs), 10)", the 
problem compiles just fine. Is this a compiler bug, or am I 
missing something obvious? I'm using dmd 2.060 on Windows 7.

Thanks,
Michael

"Adam D. Ruppe" <destructionator gmail.com> writes:

On Tuesday, 16 October 2012 at 16:12:06 UTC, Michael wrote:
 void main() {
 	import std.range, std.stdio;

The problem is that UFCS only works on functions in the global 
scope. The import inside a function makes them local, so it 
doesn't consider them in it.

This is apparently by design; Walter said that just a couple 
weeks ago, though I don't have the link right now and don't 
remember what he said the reason was.

But if you move those imports outside the function the rest of 
your code will work.

"Jonathan M Davis" <jmdavisProg gmx.com> writes:

On Tuesday, October 16, 2012 18:28:14 Adam D. Ruppe wrote:
 On Tuesday, 16 October 2012 at 16:12:06 UTC, Michael wrote:
 void main() {
 
 import std.range, std.stdio;

 
 The problem is that UFCS only works on functions in the global
 scope. The import inside a function makes them local, so it
 doesn't consider them in it.
 
 This is apparently by design; Walter said that just a couple
 weeks ago, though I don't have the link right now and don't
 remember what he said the reason was.
 
 But if you move those imports outside the function the rest of
 your code will work.

That seems like it goes against the whole "turtles all the way down" principle 
that made it so that local imports were added in the first place. I wonder what 
the reasoning was.

- Jonathan M Davis

"Michael" <pongad gmail.com> writes:

Thank you guys. I can't believe that haven't thought of that.
I still feel that this is rather odd though. I would expect to be 
able to use UFCS in the scope that imports those libraries. 
Though I can definitely see how that might lead to obscure bugs.

On Tuesday, 16 October 2012 at 17:07:36 UTC, Jonathan M Davis 
wrote:
 On Tuesday, October 16, 2012 18:28:14 Adam D. Ruppe wrote:
 On Tuesday, 16 October 2012 at 16:12:06 UTC, Michael wrote:
 void main() {
 
 import std.range, std.stdio;

 
 The problem is that UFCS only works on functions in the global
 scope. The import inside a function makes them local, so it
 doesn't consider them in it.
 
 This is apparently by design; Walter said that just a couple
 weeks ago, though I don't have the link right now and don't
 remember what he said the reason was.
 
 But if you move those imports outside the function the rest of
 your code will work.

 That seems like it goes against the whole "turtles all the way 
 down" principle
 that made it so that local imports were added in the first 
 place. I wonder what
 the reasoning was.

 - Jonathan M Davis