https://github.com/mono83/maybe

Generic Maybe monad implementation in Go
https://github.com/mono83/maybe

generics golang maybe monads

Last synced: 5 months ago
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Generic Maybe monad implementation in Go

• Host: GitHub
• URL: https://github.com/mono83/maybe
• Owner: mono83
• License: mit
• Created: 2022-08-23T14:45:20.000Z (almost 4 years ago)
• Default Branch: main
• Last Pushed: 2022-09-22T18:36:28.000Z (over 3 years ago)
• Last Synced: 2025-02-20T09:03:06.883Z (over 1 year ago)
• Topics: generics, golang, maybe, monads
• Language: Go
• Homepage:
• Size: 13.7 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
Maybe

=====

[![License: MIT](https://img.shields.io/badge/License-MIT-blue.svg)](https://opensource.org/licenses/MIT)

[![GitHub go.mod Go version of a Go module](https://img.shields.io/github/go-mod/go-version/mono83/maybe.svg)](https://github.com/mono83/maybe)

[![GoDoc reference example](https://img.shields.io/badge/godoc-reference-blue.svg)](https://pkg.go.dev/github.com/mono83/maybe)

[![Go Report Card](https://goreportcard.com/badge/github.com/mono83/maybe)](https://goreportcard.com/report/github.com/mono83/maybe)

[![CircleCI](https://dl.circleci.com/status-badge/img/gh/mono83/maybe/tree/main.svg?style=svg)](https://dl.circleci.com/status-badge/redirect/gh/mono83/maybe/tree/main)

Simple zero dependency struct-based generic monad implementation in Go.

## Installation

```bash

go get -u github.com/mono83/maybe

```

## Usage

### Instantiation

There are two main ways to create `maybe.Maybe` monadic container - it is either call to `maybe.Nothing()` or 

`maybe.Just(value)`. First will create empty monad, while second one will produce not empty monad with given value. 

Pay attention, that `maybe.Just` does not verify content of passed value, so constructions like 

`maybe.Just[error](nil)` can create not empty monads with nil value within. To avoid this behaviour use 

`maybe.Nilable`, that will perform `nil` check of given value.

In addition to raw instantiation, this library provide mapping constructor `maybe.Map`, able to convert 

`Maybe` from one type to another using mapping function

```go

n := maybe.Nothing[string]()    // String type, but empty

i := maybe.Just(1)              // Int type

s := maybe.Map(i, strconv.Itoa) // String type

```

### JSON

JSON bindings can be accessed using `github.com/mono83/maybe/json` package:

```go

import "github.com/mono83/maybe/json"

type Request struct {

	ID       int

	ParentID json.Maybe[int]

}

```

### Benchmarks

```

$ go test -bench=. -benchmem

goos: linux

goarch: amd64

pkg: github.com/mono83/maybe

cpu: Intel(R) Core(TM) i5-10400F CPU @ 2.90GHz

BenchmarkNothing-12             1000000000               0.2704 ns/op          0 B/op          0 allocs/op

BenchmarkJust-12                904382658                1.313 ns/op           0 B/op          0 allocs/op

BenchmarkPtr-12                 1000000000               1.051 ns/op           0 B/op          0 allocs/op

BenchmarkPtrNil-12              755984685                1.578 ns/op           0 B/op          0 allocs/op

BenchmarkNilableInt-12          72761029                16.37 ns/op            8 B/op          0 allocs/op

BenchmarkNilableNil-12          275986280                4.157 ns/op           0 B/op          0 allocs/op

PASS

ok      github.com/mono83/maybe 6.931s

```