Lambda recursive ...

[Remi Forax]

On 10/20/2012 06:29 PM, Maurice Naftalin wrote:
> The FAQ page with this factorial example
> (http://lambdafaq.org/can-lambda-expressions-be-used-to-define-recursive-functions/)
> actually did make that point. It makes it more emphatically now.

You can also define the recursive function and use the method referene 
syntax:
class A {
   static int fibo(int n) {
     return (n < 2)? 1: fibo(n -1) + fibo(n - 2);
   }
   ...
   Mapper<Integer, Integer> mapper = A#fibo;
}

Rémi
>
> Maurice
>
> On 19/10/2012 14:18, Aleksey Shipilev wrote:
>> On 10/19/2012 05:09 PM, Boaz Nahum wrote:
>>     
>>> interface FactInt { int invoke(int i); }
>>>
>>>    FactInt factorial = i ->
>>>                   { return i == 0 ? 1 : i * factorial.invoke(i - 1); };
>>>
>>> But the compile (b61) says:
>>> error: variable factorial might not have been initialized
>>>
>>> How can I write recursive expression like this ?
>>>       
>> Lambda can not capture the uninitialized local variable; the trick is to
>> use fields, in which case lambda will capture "this" or the reference to
>> static field [1].
>>
>> -Aleksey.
>>
>> [1]
>> https://github.com/shipilev/jdk8-lambda-samples/blob/master/src/test/java/net/openjdk/lambda/FibonacciTest.java
>>
>>
>>     
>