Rant after trying Rust a bit

[Nicholas Wilson via Digitalmars-d]

On Sunday, 26 July 2015 at 01:55:12 UTC, Enamex wrote:
> On Saturday, 25 July 2015 at 09:14:04 UTC, Jonathan M Davis 
> wrote:
>> . . .
>> auto foo(alias pred, R)(R r)
>>     if(testPred!pred && isInputRange!R && !isForwardRange!R)
>> {}
>>
>> auto foo(alias pred, R)(R r)
>>     if(testPred!pred && isForwardRange!R)
>> {}
>>
>> and be turning it into something like
>>
>> template foo(alias pred)
>>     if(testPred!pred)
>> {
>>     auto foo(R)(R r)
>>         if(isInputRange!R && !isForwardRange!R)
>>     {}
>>
>>     auto foo(R)(R r)
>>         if(isForwardRange!R)
>>     {}
>> }
>> . . .
>> - Jonathan M Davis
>
> The example(s) is confusing me. `foo!(first)(second);` isn't 
> really an alternative to `foo(first, second);`_?_. Am I 
> misreading something?

No. Yes. `first` is a compile time parameter and can be anything. 
In this case it defines a type (in examples T is used for generic 
type, and R for a range). but it can be anything, a type literal 
i.e. foo!(size_t a)(Bar b); , it can be another symbol ( a 
function, class or even another template (with is own set of 
args)! it can be varaidic as well i.e. foo!(T...)(some_args)

Second is the set of runtime parameters, which can be of types 
defined in the compile time args.