子矩阵 Ocaml

Question

let moja_matrika1 = [[1; 2]; [3; 4]];;
let moja_matrika2 = [[4; 7; 8]; [3; 2; 1]];;

let rec does_it_contain (lis1, lis2) =
if (List.hd lis1 = []) then false
else if (List.hd lis1 = lis2) then true
else does_it_contain ((List.tl lis1), lis2);;

let rec does_it (matrix, lis1) =
if (matrix = []) then false
else if does_it_contain (List.hd matrix, List.hd lis1) = true then true
else does_it (List.tl matrix, lis1);;

does_it (moja_matrika1, moja_matrika2);;

我试图检查一个矩阵是否是另一个矩阵的子矩阵。但我必须使用类型列表列表。我无法使用任何定义的列表函数。显然我正在使用 List hd, tl 但我会替换它。

当我尝试调用我不理解的函数时出现错误。

   does_it (moja_matrika1, moja_matrika2);;
Error: This expression has type int list list
       but an expression was expected of type 'a list list list
       Type int is not compatible with type 'a list # 

请帮忙！

Answer 1

does_it_contain 和 does_it 的签名分别是 :

  'a list list * 'a list -> bool 
  'a list list list * 'a list list -> bool  

他们都不能接受 2 个矩阵作为参数（

'a list

和

'a list list list

不是你期望的矩阵）

此外，您可以像 C 或 java 一样编写函数代码：在 Ocaml 中，参数不通过括号传递。括号用于元组 - 在这种情况下没有用。

Answer 2

我明白了。

let rec does_it_contain (lis1, lis2) =
    if rep lis1 = [] then false
    else if rep lis2 = [] then false
  else if (  glava lis1 = glava lis2) then true
 else does_it_contain ( lis1, rep lis2);;

let rec does_it (matrica, matrica1) =
    if rep matrica = [] then false
    else if rep matrica1 = [] then false
    else if does_it_contain ( glava matrica, glava matrica1) = true then true
    else  does_it ( rep matrica,  rep matrica1);;


does_it(moja_matrika1, moja_matrika2);;

rep 是 List.tl 的替代品，glava 是 List.hd 的替代品。