digitalmars.D.learn - Closures not yet supported in CTFE's
- JS (7/7) Jul 27 2013 When I try to pass a lambda to a template, I get the subject
- H. S. Teoh (9/19) Jul 27 2013 Y'know, it would really help if you (1) show the full code that's
When I try to pass a lambda to a template, I get the subject
error.
(string x) => { return x~"1"; }
But when I jsut do
(string x) => x~"1"
it works....
Come on!!!
Jul 27 2013
On Sat, Jul 27, 2013 at 06:47:04PM +0200, JS wrote:When I try to pass a lambda to a template, I get the subject error. (string x) => { return x~"1"; }Drop the "=>", that syntax doesn't do what you think it does.But when I jsut do (string x) => x~"1" it works.... Come on!!!Y'know, it would really help if you (1) show the full code that's failing, and (2) calm down before posting to the forum. I understand that compiler bugs/limitations can be very aggravating, but you're much more likely to get a helpful reply that way. T -- He who does not appreciate the beauty of language is not worthy to bemoan its flaws.
Jul 27 2013
On Saturday, 27 July 2013 at 17:18:29 UTC, H. S. Teoh wrote:On Sat, Jul 27, 2013 at 06:47:04PM +0200, JS wrote:The code wouldn't help because that is not where the error is at. I don't know why there is a special syntax for a direct return. (string x) => { return x; } is trying to return a function that returns x using closure because of x is outside the inside function. (string x) { return x; } is what I was trying to do. I knew that (string x) => ...; was simple notation for return ... but didn't think I was returning a function in any way.When I try to pass a lambda to a template, I get the subject error. (string x) => { return x~"1"; }Drop the "=>", that syntax doesn't do what you think it does.But when I jsut do (string x) => x~"1" it works.... Come on!!!Y'know, it would really help if you (1) show the full code that's failing, and (2) calm down before posting to the forum. I understand that compiler bugs/limitations can be very aggravating, but you're much more likely to get a helpful reply that way.
Jul 27 2013
On Saturday, 27 July 2013 at 23:54:28 UTC, JS wrote:
The code wouldn't help because that is not where the error is
at. It is because I thought => was used for lambda's as it is
return.
(string x) => { return x; } is trying to return a function that
returns x using closure because of x is outside the inside
function.
(string x) { return x; } is what I was trying to do. I knew
that (string x) => ...; was simple notation for return ... but
didn't think I was returning a function in any way.
It was a source of confusion for me at first as well, as I
the case, unfortunately, as { ... } is a delegate literal in D,
so you have to use the full `(a) { ... }` syntax. It's annoying,
but somewhat more bearable if you've worked with Javascript or
LUA before, since they have pretty much the same syntax for
function literals.
Jul 27 2013
"anonymous" <anonymous example.com>
On Sunday, 28 July 2013 at 01:17:00 UTC, Meta wrote:
[...]
It was a source of confusion for me at first as well, as I
the case, unfortunately, as { ... } is a delegate literal in D,
so you have to use the full `(a) { ... }` syntax.
(a) { ... }
a => { ... }
Jul 27 2013
On Saturday, 27 July 2013 at 23:54:28 UTC, JS wrote:On Saturday, 27 July 2013 at 17:18:29 UTC, H. S. Teoh wrote:[...][...]Y'know, it would really help if you (1) show the full code that's failing,The code wouldn't help because that is not where the error is at.It's not so much about providing the full source of your project, but more about a reduced test case, a little snippet that compiles (or should compile in your opinion). It lowers the barrier for helpers quite a bit.(foo) => {bar} bar. In D: (foo) {bar} Lambdas.I don't know why there is a special syntax for a direct return.Not sure, I'm understanding this right. You mean, why do we need the arrow syntax when we can do the same thing with the braces syntax? (Expression Lambdas vs Statement Lambdas)? It's just that D has a(string x) => { return x; } is trying to return a function that returns x using closure because of x is outside the inside function. (string x) { return x; } is what I was trying to do. I knew that (string x) => ...; was simple notation for return ... but didn't think I was returning a function in any way.I feel like you may have missed this: In D (string x) => x is equivalent to (string x) { return x; } [1] http://msdn.microsoft.com/en-US/library/vstudio/bb397687.aspx
Jul 27 2013