How to invert bool false/true in alias compose?

[Marcone]

On Saturday, 7 December 2019 at 04:05:23 UTC, mipri wrote:
> On Saturday, 7 December 2019 at 04:00:53 UTC, Marcone wrote:
>> import std;
>>
>> alias cmd = compose!(to!bool, wait, spawnShell, to!string);
>>
>> void main(){
>> 	writeln(cmd("where notepad.exe"));
>> }
>>
>>
>> Result:
>>
>> C:\Windows\System32\notepad.exe
>> C:\Windows\notepad.exe
>> false
>>
>>
>> The result show "false" because good spawnshell command return 
>> 0 and 0 to bool is false. But I want to invert false to true 
>> to get true or false if command success.
>
> These all work:
>
> alias cmd = compose!(unaryFun!"!a", to!bool, wait, spawnShell, 
> to!string);
>
> alias cmd = compose!("!a", to!bool, wait, spawnShell, 
> to!string);
>
> alias cmd = compose!(b => !b, to!bool, wait, spawnShell, 
> to!string);

Thank you very much mipri! Work very well!