Sting.map和String.mapi在OCaml中的区别。指南说前者“应用函数”,而后者“调用函数”?那是什么意思?我还尝试了这个:
String.map (fun x -> Char.uppercase_ascii x) "lala";;
而且它是有效的。但如果我试着
String.mapi (fun x -> Char.uppercase_ascii x) "lala";;
我得到了
Error: This expression has type int but an expression was expected of type char