在 J 中定义连词时出现奇怪的长度错误
我正在玩 J 中的副词和连词，遇到了一个奇怪的问题。我定义了一个名为 persistence 的简单副词，可用于查看在计算数字的数字乘积或数字和时生成的数字的级数。
S =: 1 : 'u/@:("."0)@":^:a:"0'
+ S 234 得到 234 9。然后我用它创建了另一个副词来计算数字的持久性。
P =: 1 : '<:@#@(u S)"0'
+ P 234 给我们 1。现在，假设我们想要找到 30 以下的所有数字，且附加持久性为 2，然后查看由 S 为每个数字生成的列表，例如，
+ S I. 2 = + P i.30
这将生成以下列表：
19 10 1
28 10 1
29 11 2
到目前为止，一切顺利。现在，我想把它变成一个连词，它的左侧包含用于持久性的动词，右侧包含用于限制列表的数字。 （上面示例中的 2。）这是我对该连词的定义：
Q =: 2 : 'u S I. n = u P'
如果我在 J 控制台中输入表达式 + Q 2，我会得到以下结果：
+/@:("."0)@":^:a:"0 I. 2 = <:@#@(+/@:("."0)@":^:a:"0)"0
This is完全正确，如果我使用 i.30 等参数运行完整表达式，它可以正常工作：
+/@:("."0)@":^:a:"0 I. 2 = <:@#@(+/@:("."0)@":^:a:"0)"0 i.30
但是，当我输入表达式 + Q 2 i.30 时进入 J 控制台，我收到“长度错误”。为什么？！ + Q 2 不是完全等同于 +/@:("."0)@":^:a:"0 I. 2 = <:@#@(+ /@:("."0)@":^:a:"0)"0？
我完全被难住了。我错过了什么？我已经在定义中玩过等级了结合和之外我只是不明白。
I'm playing around with adverbs and conjunctions in J, and have run across a strange problem. I've defined a simple adverb called persistence that can be used to view the progression of numbers generated when calculating the digital product or digital sum of a number.
S =: 1 : 'u/@:("."0)@":^:a:"0'
+ S 234 gives us 234 9. I then used this to create another adverb that calculates the persistence of a number.
P =: 1 : '<:@#@(u S)"0'
+ P 234 gives us 1. Now, imagine we want to find all numbers below 30 with additive persistence of 2 and then view the list generated by S for each number, e.g.,
+ S I. 2 = + P i.30
This generates the following list:
19 10 1
28 10 1
29 11 2
So far, so good. Now, I wanted to take this and turn it into a conjunction, the left-hand side of which contains the verb to use for persistence and the right-hand side of which contains the number used to limit the list. (2 in the example above.) Here's my definition of that conjunction:
Q =: 2 : 'u S I. n = u P'
If I enter the expression + Q 2 into the J console, I get back the following:
+/@:("."0)@":^:a:"0 I. 2 = <:@#@(+/@:("."0)@":^:a:"0)"0
This is exactly correct, and if I run the full expression with an argument such as i.30, it works fine:
+/@:("."0)@":^:a:"0 I. 2 = <:@#@(+/@:("."0)@":^:a:"0)"0 i.30
However, when I enter the expression + Q 2 i.30 into the J console, I get back a 'length error'. Why?! Isn't + Q 2 exactly equivalent to +/@:("."0)@":^:a:"0 I. 2 = <:@#@(+/@:("."0)@":^:a:"0)"0?
I'm completely stumped. What am I missing? I've played around with rank both inside the definition of the conjunction and outside of it. I just don't get it.
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+ Q 2与您提供的表达式完全相同，但在表达式中使用它时，就好像它在括号中一样。一般来说，
fgh y!=(fgh) y。在后者中，fg h定义了一个train。例如：您可以通过添加对 y 的引用来修复连词，如下所示：
+ Q 2is exactly equivalent to the expression you provided, but when using it in an expression it is as if it is in parenthesis.In general
f g h y!=(f g h) y. In the latterf g hdefines a train. For example:You can fix your conjunction by adding a reference to y to it like this: