ocaml获取语法错误[已关闭]

我在“module usingTable:TABLE=”行中遇到语法错误,当我尝试在oCaml中运行此代码时,usingTable一词被突出显示为红色。我想创建如下执行示例所示格式的表。它怎么了?我使用的环境是 https://try.ocamlpro.com/fun-demo/tryocaml_index.html#path%3Dtries 因为我不明白如何在windows中使用cygwin或oCaml Bash。

module type TABLE = 
sig
  type table 
  val emptyTable : table
  val printTable : table -> string
  val create_table : string * string list * (string list) list -> table  
end;;

module usingTable : TABLE =
struct
  let emptyTable = ()
  let table = (string * (string * string list) list) 

  let rec printTable aTable = match aTable with
      ()->""
    | (title, [data]) -> "\n"^title^"\n\n"^printTable(data)
    | [(col,cont)::t] -> col^"   "^printTable([t]) 
end;;

let atable = usingTable.emptyTable;;
let atable = ("Student", [("Id", ["2";"4";"7";"9"]);
                          ("Name", ["Jim";"Linnea";"Steve";"Hannah"]);
                          ("Gender",["Male";"Female";"Male";"Female"]);
                          ("Course",["Geography";"Economics";"Informatics";"Geography"])
                         ]);; 
print_string (usingTable.printTable atable) ;;