I have the following code I've been developing, an alternate while loop:
_while = (cond, act) => cond && act() & _while(cond, act)
In this case act() is intended to alter the end result of cond with each iteration until cond is evaluated to false, to which then the loop is meant to end...
I've tried to test this out by attempting to determine the length of a string through stepping through the string using my code. As a result, my code is the following:
len = 0; _while(!!("qwerty")[len], ()=>++len);
Now, my thoughts were that this code will basically step through and test for the presence of each character within the string, incrementing len until it attempts "qwe"[6] which is undefined, and the !! renders the undefined returned value to false, exiting the loop, with the value of len being equal to 6...
However, I'm not even getting that far... for some reason this loop keeps going, and gives up with an error of InternalError: too much recursion
Can anyone see what I've done wrong with my code? I'd like to preserve what I can of my original code without having to resort to a native for or while loop...
The expression !!("qwerty")[len]) is evaluated before the call to _while is actually made. At that time, len is 0, so the result of the expression will be true.
To fix this, you could require cond to be a function, much like act is. This way, you can evaluate the condition each time through the loop. I guess it would look like this (though I'm not JavaScript savvy):
_while = (cond, act) => cond() && act() & _while(cond, act)
The given example would then become
len = 0; _while(()=>!!("qwerty")[len], ()=>++len);