functional way doing array stuff/ lambda functions

[cym13 via Digitalmars-d-learn]

On Sunday, 13 December 2015 at 03:08:33 UTC, Namal wrote:
> On Saturday, 12 December 2015 at 23:50:55 UTC, Xinok wrote:
>> [...]
>
>
> 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]

As cryptic as it is this means that the range you passed to 
reduce is empty. Reduce needs it not to be because as I said it 
needs a seed and as you didn't pass one explicitely as argument 
it tries to take the first element of the range (and fails 
obviously). You can either pass it a seed explicitely or add a 
non-empty check before the return.