f# - 元组列表上的模式匹配

Question

如果我想添加元组列表的所有元素，我会收到以下错误

let rec addTupLst (xs: 'a * 'a list) =
    match xs with
    | (a, b) :: rst -> a + b + (addTupLst rst)
    | _ -> 0

addTupLst [(1, 2)]

我收到警告

error FS0001: This expression was expected to have type
'a * 'a list
but here has type
'b list

是否不可能以这种方式在元组列表上进行模式匹配，还是存在另一个错误？

Answer 1

你只是忘记了一对括号

let rec addTupLst (xs: ('a * 'a) list) =
     match xs with
     | (a, b) :: rst -> a + b + (addTupLst rst)
     | _ -> 0

addTupLst [(1, 2)]