gust 
Golang ergonomic declarative generics module inspired by Rust.
Go Version
go≥1.18
Features
Result
Avoid if err != nil, handle result with chain methods.
- Result Example
func ExampleResult_AndThen() {
var divide = func(i, j float32) gust.Result[float32] {
if j == 0 {
return gust.Err[float32]("j can not be 0")
}
return gust.Ok(i / j)
}
var ret float32 = divide(1, 2).AndThen(func(i float32) gust.Result[float32] {
return gust.Ok(i * 10)
}).Unwrap()
fmt.Println(ret)
// Output:
// 5
}
func ExampleResult_UnwrapOr() {
const def int = 10
// before
i, err := strconv.Atoi("1")
if err != nil {
i = def
}
fmt.Println(i * 2)
// now
fmt.Println(gust.Ret(strconv.Atoi("1")).UnwrapOr(def) * 2)
// Output:
// 2
// 2
}
Option
Avoid (T, bool) and if *U != nil, handle value with Option type.
- Option Example
func ExampleOption() {
type A struct {
X int
}
var a = gust.Some(A{X: 1})
fmt.Println(a.IsSome(), a.IsNone())
var b = gust.None[A]()
fmt.Println(b.IsSome(), b.IsNone())
var x = b.UnwrapOr(A{X: 2})
fmt.Println(x)
var c *A
fmt.Println(gust.Ptr(c).IsNone())
c = new(A)
fmt.Println(gust.Ptr(c).IsNone())
type B struct {
Y string
}
var d = opt.Map(a, func(t A) B {
return B{
Y: strconv.Itoa(t.X),
}
})
fmt.Println(d)
// Output:
// true false
// false true
// {2}
// true
// false
// Some({1})
}
