first()

Syntax

first(list, expr)

Finds and returns the first item in the list that satisfies expr. It sets _ for current element value, and _i for index of that element. break can be called inside the iteration code, using its argument value instead of the current item. continue has no sense and cannot be called inside first call.

// first prime after 1000
first(range(1000, 10000), n = _; !first(range(2, sqrt(n) + 1), !(n % _))); // 1009

Notice in the example above, that we needed to rename the outer _ to be able to use in in the inner first call