functional way doing array stuff/ lambda functions

[Namal via Digitalmars-d-learn]

On Saturday, 12 December 2015 at 23:50:55 UTC, Xinok wrote:
> On Saturday, 12 December 2015 at 23:36:43 UTC, cym13 wrote:
>> ...
>> So, in your example:
>>
>> int product(const ref int[] arr) {
>>     import std.array:     array;
>>     import std.algorithm: reduce;
>>
>>     arr = arr.reduce!((p, i) => p*i).array;
>> }
>
> A good post overall but you got reduce wrong. In D, reduce 
> computes and returns the result immediately, not a lazy range. 
> The following code is correct:
>
> int product(const ref int[] arr) {
>     import std.array:     array;
>     import std.algorithm: reduce;
>
>     return arr.reduce!((p, i) => p*i)();
> }
>
> Example: http://dpaste.dzfl.pl/fc2c2eab2d02


I tried this, it compiles, but crashes when I try to run it:

object.Exception@/usr/include/dmd/phobos/std/algorithm/iteration.d(2481): Enforcement failed
----------------
??:? pure @safe void 
std.exception.bailOut!(Exception).bailOut(immutable(char)[], 
ulong, const(char[])) [0x43a547]
??:? pure @safe bool std.exception.enforce!(Exception, 
bool).enforce(bool, lazy const(char)[], immutable(char)[], ulong) 
[0x43a4c4]
??:? pure @safe int 
std.algorithm.iteration.__T6reduceS305ep1247productFKxAiZ9__lambda2Z.reduce!(const(int)[]).reduce(const(int)[]) [0x43a2ed]
??:? int ep124.product(ref const(int[])) [0x439d49]
??:? _Dmain [0x43a229]
??:? 
_D2rt6dmain211_d_run_mainUiPPaPUAAaZiZ6runAllMFZ9__lambda1MFZv 
[0x448b9a]
??:? void rt.dmain2._d_run_main(int, char**, extern (C) int 
function(char[][])*).tryExec(scope void delegate()) [0x448af0]
??:? void rt.dmain2._d_run_main(int, char**, extern (C) int 
function(char[][])*).runAll() [0x448b56]
??:? void rt.dmain2._d_run_main(int, char**, extern (C) int 
function(char[][])*).tryExec(scope void delegate()) [0x448af0]
??:? _d_run_main [0x448a4d]
??:? main [0x4447ad]
??:? __libc_start_main [0xd9f09ec4]