基本用法

type person = {Name: string; Age: int}   // Defines person record

let user1 = {Name = "John Doe"; Age = 27} // creates a new person
let user2 = {user1 with Age = 28}         // creates a copy, with different Age
let user3 = {user1 with Name = "Jane Doe"; Age = 29} //creates a copy with different Age and Name

let printUser user =
    printfn "Name: %s, Age: %i" user.Name user.Age

printUser user1 // Name: John Doe, Age: 27
printUser user2 // Name: John Doe, Age: 28
printUser user3 // Name: Jane Doe, Age: 29