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example_option_test.go
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/
example_option_test.go
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package fluent
import (
"fmt"
)
func Divide(a, b int) Option[int] {
if b == 0 {
return Empty[int]()
} else {
return Present(a / b)
}
}
func Double(a int) int {
return a * 2
}
func String(a int) string {
return fmt.Sprintf("%d", a)
}
func ExampleOption_goodDivision() {
// Mapping operations can be chained if input and output types are the same
var option Option[int] = Divide(6, 3).Map(Double)
// But mapping operations with different input and output types must use
// package level functions due to language limitations.
message := MapOption(option, String)
var result string
if message.IsPresent() {
result = message.Get()
} else {
result = "empty"
}
fmt.Println(result)
// Output: 4
}
func ExampleOption_badDivision() {
var option Option[int] = Divide(100, 0).Map(Double)
message := MapOption(option, String)
var result string
if message.IsPresent() {
result = message.Get()
} else {
result = "empty"
}
fmt.Println(result)
// Output: empty
}