`split` 函数的逆：`join` 使用分隔符的字符串答案

【问题标题】：Inverse of `split` function: `join` a string using a delimeter`split` 函数的逆：`join` 使用分隔符的字符串
【发布时间】：2026-01-16 20:05:01
【问题描述】：

在 Red 和 Rebol(3) 中，您可以使用 split 函数将字符串拆分为项目列表：

>> items: split {1, 2, 3, 4} {,}
== ["1" " 2" " 3" " 4"]

join 将项目列表转换为字符串的对应反函数是什么？它的工作方式应该类似于以下内容：

>> join items {, }
== "1, 2, 3, 4"

【问题讨论】：

Ren-C 称之为 delimit，它的特化为 spaced: specialize 'delimit [delimiter: space] 和 unspaced: specialize 'delimit [delimiter: blank]。为了使它们更有用，分隔符省略了空格和空白（R3-Alpha 和 Red 中的“未设置！”和“无！”），然后巧妙地合并分隔符......所以 delimit ["a" if false ["b"] if false ["c"] "d"] {, } 将是 "a, d"。

标签： series rebol rebol3 red

【解决方案1】：

目前还没有内置函数，你必须自己实现它：

>> join: function [series delimiter][length: either char? delimiter [1][length? delimiter] out: collect/into [foreach value series [keep rejoin [value delimiter]]] copy {} remove/part skip tail out negate length length out]
== func [series delimiter /local length out value][length: either char? delimiter [1] [length? delimiter] out: collect/into [foreach value series [keep rejoin [value delimiter]]] copy "" remove/part skip tail out negate length length out]
>> join [1 2 3] #","
== "1,2,3"
>> join [1 2 3] {, }
== "1, 2, 3"

每个请求，这里是分成更多行的函数：

join: function [
    series 
    delimiter
][
    length: either char? delimiter [1][length? delimiter] 
    out: collect/into [
        foreach value series [keep rejoin [value delimiter]]
    ] copy {} 
    remove/part skip tail out negate length length 
    out
]

【讨论】：

函数放在多行上会更容易阅读和理解。

【解决方案2】：

以下功能有效：

myjoin: function[blk[block!] delim [string!]][
    outstr: ""
    repeat i ((length? blk) - 1)[
        append outstr blk/1
        append outstr delim
        blk: next blk ]
    append outstr blk ]

probe myjoin ["A" "B" "C" "D" "E"] ", "

输出：

"A, B, C, D, E"

【讨论】：

【解决方案3】：

rejoin 有一个旧的修改

rejoin: func [
    "Reduces and joins a block of values - allows /with refinement." 
    block [block!] "Values to reduce and join" 
    /with join-thing "Value to place in between each element" 
][ 
    block: reduce block 
    if with [ 
        while [not tail? block: next block][ 
            insert block join-thing 
            block: next block
       ] 
       block: head block 
    ] 
    append either series? first block [ 
       copy first block
    ] [
       form first block
    ] 
    next block 
]

这样称呼它重新加入/使用 [..] 分隔符

但我很确定，还有其他甚至更旧的解决方案。

【讨论】：