我有一个特殊的函数,它接受一个列表,列表的每个成员必须满足多个要求 . 如何在perl6函数中设置它?
sub specialFunc(List $x) {};
(1) $x is a list # easy, List $x, but what about the following:
(2) each member of $x is numeric
(3) each member of $x is positive
(4) each member of $x is greater than 7
(5) each member of $x is odd number
(6) each member of $x is either the square or the cube of an even number plus 1;
谢谢您的帮助 !!
lisprog
1 回答
Perl 6类型系统不够灵活,无法以声明方式表达此类约束,但您可以在参数中添加
where
子句,以根据自定义表达式检查传入的参数 .为清楚起见,我将用于测试每个数字的表达式分解为
subset
:您可以更进一步,并将整个
where
子句分解为subset
:PS:我认为你的要求(5)可能是多余的,因为要求(6)似乎只满足奇数,但我对数论并不大,所以我不确定 .