鍵入縮寫

型別縮寫允許你在現有型別上建立別名，以便為它們提供更有意義的感官。

// Name is an alias for a string
type Name = string

// PhoneNumber is an alias for a string
type PhoneNumber = string

然後你可以像使用任何其他型別一樣使用別名：

// Create a record type with the alias
type Contact = {
    Name : Name
    Phone : PhoneNumber }

// Create a record instance
// We can assign a string since Name and PhoneNumber are just aliases on string type
let c = {
    Name = "Foo"
    Phone = "00 000 000" }

printfn "%A" c

// Output
// {Name = "Foo";
// Phone = "00 000 000";}

小心，別名不檢查型別的一致性。這意味著可以將兩個目標相同型別的別名分配給彼此：

let c = {
    Name = "Foo"
    Phone = "00 000 000" }
let d = {
    Name = c.Phone
    Phone = c.Name }

printfn "%A" d

// Output
// {Name = "00 000 000";
// Phone = "Foo";}