Higher-order functions?

[Xan]

On Wednesday, 11 April 2012 at 09:17:12 UTC, Jacob Carlborg wrote:
> On 2012-04-11 10:45, Xan wrote:
>> Good answer.
>>
>> For the other hand, what is the simplest method for 
>> implementing this
>> (in pseucode) in D:
>>
>> Sure:
>>
>> FUNC someprocedure(int a, int b, func<int, int: int> f) int
>> RETURN f(a, b)
>> }
>>
>> And call it with:
>>
>> IO.writeLine("add: " .. someprocedure(2, 3, { a, b => a + b }))
>> IO.writeLine("multiply: " .. someprocedure(2, 3, { a, b => a * 
>> b }))
>>
>> (Read the => as "gives")
>>
>> Is it possible to have this?
>>
>
> If I understand the above code correctly:
>
> import std.stdio;
>
> int someprocedure (int a, int b, int delegate (int, int) f)
> {
>     return f(a, b);
> }
>


Yes, you undertood correcty.

Your code gives me an error:

$ gdmd-4.6 funcions.d
funcions.d:10: expression expected, not '>'
funcions.d:10: found 'a' when expecting ','
funcions.d:11: expression expected, not '>'
funcions.d:11: found 'a' when expecting ','

> void main ()
> {
>     writeln("add: ", someprocedure(2, 3, (a, b) => a + b));
>     writeln("multiply: ", someprocedure(2, 3, (a, b) => a * b));
> }