如何使用SML中的记录创建数据类型的实例？

Question

例如，如果你有

datatype 'a DT =
   thingy of {field1: int, field2: int}
| Empty DT;

你怎么能够创造＆＃34; thingy＆＃34;在功能中填写其字段？假设您拥有每个字段所需的值。

Answer 1

- datatype 'a DT = thingy of {x: int, y: int} | Empty; datatype 'a DT = Empty | thingy of {x:int, y:int} - thingy {x = 5, y = 4}; val it = thingy {x=5,y=4} : 'a DT - fun f x y = thingy {x = x, y = y}; val f = fn : int -> int -> 'a DT