Sum string lengths

[MoonlightSentinel]

On Wednesday, 13 May 2020 at 13:52:13 UTC, Andrey wrote:
> Hi,
> I want to sum lengths of all strings in array:
>> auto data = ["qwerty", "az", "!!!!"];
>
> Fold and reduce doesn't work:
>> auto result = data.fold!`a + b.length`(0U);
>
> gives error:
>> static assert:  "Incompatible function/seed/element: 
>> binaryFun/uint/string"
>
> How to do it in one line?

The problem is that you provide a uint as seed (which determines 
the type of the accumulated value) but your function returns a 
ulong (or rather size_t).

You can fix this by changing the type of your seed, either use 
ulong or size_t.

auto result = data.fold!`a + b.length`(0UL);

auto result = data.fold!`a + b.length`(size_t(0));