nilo

nilo

Go Optionals library for handling nil values and some errors (partially inspired in Java Optionals)

Caveats

• This library requires Go 1.23+

Intallation

go get -u github.com/javiorfo/nilo@latest

Example

Examples here

package main

import (
  "errors"
  "fmt"
  "slices"

  "github.com/javiorfo/nilo"
)

func main() {
  var numbers []int

  evenNumbersOpt := nilo.Of(numbers).Filter(func(n []int) bool {
    return slices.Contains(n, 1)
  })

  if evenNumbersOpt.IsPresent() {
    fmt.Println("One is present")
  } 

  nilo.FromTuple(getUser(true)).AndThen(getUser2).IfPresent(print)

  _, err := test(false).OrError(errors.New("some err"))
  fmt.Println(err.Error())

  fmt.Println(test(true).MapToString(func(v string) string { return v + ", World" }).OrElse("another string"))
}

func test(b bool) nilo.Optional[string] {
  if b {
    return nilo.Of("Hello")
  }
  return nilo.Empty[string]()
}

func print[T any](v *T) {
  fmt.Printf("Value: %#v\n", *v)
}

func getUser(b bool) (*int, error) {
  if b {
    i := 1
    return &i, nil
  }
  return nil, errors.New("error")
}

func getUser2(p *int) (*int, error) {
  if *p == 0 {
    return 0, errors.New("error")
  }
  r := *p + 2
  return &r, nil
}

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