匹配失败问题OCaml

我的OCaml代码出现匹配失败，我不知道可能是什么问题。我试图只处理一个案例，并从中找出问题出在哪里，但我收到的错误是：

Exception: Match_failure ("hw2.ml", 49, 0).

代码：

let rec compileStack(il : instr list) (st : float list) =
 match (il,st) with
 [],[_] -> List.hd st
 |((Push f)::t),[_] -> compileStack t (f::st)
 |(Swap)::t, h2::h1::st   -> compileStack t (h2::h1::st)
 |(Calculate op)::t, h1::h2::st ->
  match op with
    Plus -> compileStack t (h2+.h1::st)
  | Minus -> compileStack t (h2-.h1::st)
  | Times -> compileStack t (h2*.h1::st)
  | Divide -> compileStack t (h2/.h1::st)  ;;                               

let execute (li : instr list) : float =
  let stack = [] in
  compileStack li stack;;   

---

如果您有任何建议，我们将不胜感激，我们已经为此坚持了2个小时了

编译时，请注意编译器的输出。如果它说

Warning ...: this pattern-matching is not exhaustive.

那通常意味着你跳过了一些案子。顺便说一下，编译器提供了一个遗漏案例的示例

考虑到你的问题，我会把不同的工作分成不同的功能——这会让你更容易处理这些情况；另外，不要忘记堆栈下溢，当堆栈中没有足够的数据执行交换或二进制算术运算时，就会发生这种情况。请参见下面的示例

(* just type aliases for convenience *)
type stack = float list
type binop = float -> float -> float

(* helper function to prevent nested pattern matching below *)
let denote_operation (op : oper) : binop =
  match op with
    | Plus   -> ( +. )
    | Minus  -> ( -. )
    | Times  -> ( *. )
    | Divide -> ( /. )

(* This function executes only 1 instruction and 
   returns 'stack option', which may signal stack underflow *)
let execute_instruction (i : instr) (st : stack) : stack option =
  match i with
    | Push f -> Some (f :: st)
    | Swap ->
       (match st with
          | y :: x :: st' -> Some (x :: y :: st')
          | _ -> None)
    | Calculate op ->
       (match st with
          | y :: x :: st' -> Some ((denote_operation op x y) :: st')
          | _ -> None)

(* this function deals with a bunch of instructions *)
let rec execute_program (il : instr list) (st : stack) : stack option =
  match il with
    | [] -> Some st
    | i :: il' ->
       match (execute_instruction i st) with
         | None -> None
         | Some st' -> execute_program il' st'

---

编译时，请注意编译器的输出。如果它说

Warning ...: this pattern-matching is not exhaustive.

那通常意味着你跳过了一些案子。顺便说一下，编译器提供了一个遗漏案例的示例

考虑到你的问题，我会把不同的工作分成不同的功能——这会让你更容易处理这些情况；另外，不要忘记堆栈下溢，当堆栈中没有足够的数据执行交换或二进制算术运算时，就会发生这种情况。请参见下面的示例

(* just type aliases for convenience *)
type stack = float list
type binop = float -> float -> float

(* helper function to prevent nested pattern matching below *)
let denote_operation (op : oper) : binop =
  match op with
    | Plus   -> ( +. )
    | Minus  -> ( -. )
    | Times  -> ( *. )
    | Divide -> ( /. )

(* This function executes only 1 instruction and 
   returns 'stack option', which may signal stack underflow *)
let execute_instruction (i : instr) (st : stack) : stack option =
  match i with
    | Push f -> Some (f :: st)
    | Swap ->
       (match st with
          | y :: x :: st' -> Some (x :: y :: st')
          | _ -> None)
    | Calculate op ->
       (match st with
          | y :: x :: st' -> Some ((denote_operation op x y) :: st')
          | _ -> None)

(* this function deals with a bunch of instructions *)
let rec execute_program (il : instr list) (st : stack) : stack option =
  match il with
    | [] -> Some st
    | i :: il' ->
       match (execute_instruction i st) with
         | None -> None
         | Some st' -> execute_program il' st'

---

失败测试的输入数据是什么？顺便说一句，（il，st）上的模式匹配并不是详尽无遗的：您错过了很多案例。这似乎是你的问题。失败测试的输入数据是什么？顺便说一句，（il，st）上的模式匹配并不是详尽无遗的：您错过了很多案例。这似乎是你的问题。