为什么 Perl 6 序列 'A' ... 'AA' 只有一个元素? [英] Why does the Perl 6 sequence 'A' ... 'AA' have only one element?

问题描述

今天我注意到序列 'A' ... 'AA' 只包含一个元素:

<代码>>'A' ... 'AA'(一种)

我认为它会包含 27:字母加上最后的 AA.

如果我明确提供一个生成器，它会:

<代码>>'A', *.succ ... 'AA'(A B C D E F G H I J K L M N O P Q R S T U V W X Y Z AA)

文档说默认生成器是 *.succ 或 *.pred 取决于端点的比较方式.但是:

<代码>>'A' cmp 'AA'较少的

所以看起来我应该默认使用 *.succ 生成器.我绝对没有得到 *.pred 生成器:

<代码>>'A', *.pred ... 'AA'递减超出范围在 <unknown file> 的任何代码中1号线

这是怎么回事?

解决方案

查看使用的代码:rakudo/operators

您的代码与

非常相似

"A", *.succ ...^ * gt "AA"

("B" gt "AA" 是 True)

和 Curt Tilmes 的代码类似

"A", *.succ ...^ {$_ gt "ZZ" or .chars >"ZZ".chars}"A", *.succ ...^ {$_ gt "YY" 或 .chars >"YY".chars}

("Z" gt "YY" 和 "AAA".chars > "ZZ".chars 是 True )

Today I noticed that the sequence 'A' ... 'AA' contains only one element:

> 'A' ... 'AA'
(A)

I thought it would contain 27: the alphabet plus the final AA.

If I explicitly provide a generator, it does:

> 'A', *.succ ... 'AA'
(A B C D E F G H I J K L M N O P Q R S T U V W X Y Z AA)

The docs say that the default generator is either *.succ or *.pred depending on how the end points compare. But:

> 'A' cmp 'AA'
Less

So it seems I should be getting the *.succ generator by default. I'm definitely not getting the *.pred generator:

> 'A', *.pred ... 'AA'
Decrement out of range
  in whatevercode  at <unknown file> line 1

What's going on here?

解决方案

see which code it is used: rakudo/operators

your code is very similar to

"A", *.succ ...^ * gt "AA"

("B" gt "AA" is True)

and code by Curt Tilmes is similar to

"A", *.succ ...^ {$_ gt "ZZ" or .chars > "ZZ".chars}
"A", *.succ ...^ {$_ gt "YY" or .chars > "YY".chars}

("Z" gt "YY" and "AAA".chars > "ZZ".chars are True )

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