学习 f# 使用 fparsec 解析一些分隔数据。我正在使用 sepBy 来获取结果列表并过滤掉空结果。我不想要空的项目，但我确实想知道这些项目的位置。有没有更好的方法来获取索引而不是 List.mapi，然后过滤掉空的？分隔数据内部将有其他分隔数据（代表子项）。
type result = {value:string; index:int}
type parent = {results:result list; index:int}
let delims = "|^"
let pipeandcarrotdata = "|A^B^C||B|C"
let zipi res = List.mapi (fun i item -> res i item)
let zipPipes = zipi (fun i t -> {results = t; index = i})
let zipCarrots = zipi (fun i t -> {value = t; index = i})
let cleanlist predicate = List.filter (fun i -> predicate i)
let cleanPipes = cleanlist (fun t -> t.results.IsEmpty <> true)
let cleanCarrots = cleanlist (fun t -> t.value <> "")
let collect items = List.mapi (fun i item -> {value = item; index = i}) items
let cleanEmpties items = List.filter (fun item -> item.value <> "") items
let pCarrots = sepBy (manyChars (noneOf delims)) (pstring "^") |>> (zipCarrots >> cleanCarrots)
let pPipes = sepBy pCarrots (pstring "|") |>> (zipPipes >> cleanPipes)
test pPipes pipeandcarrotdata
结果：
[{results = [{value = "A";index = 0;}; {value = "B";index = 1;}; {value = "C";index = 2;}]; index = 1;};
{results = [{value = "B"; index = 0;}]; index = 3;};
{results = [{value = "C"; index = 0;}];index = 4;}]
稍后我将需要支持更复杂的层次结构，并且我想避免再编写 5-6 个函数，如“cleanPipes”和“cleanCarrots”，然后再编写另外 5-6 个函数，如“zipPipes”和“zipCarrots”。