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https://github.com/elliotchance/pie

πŸ• Enjoy a slice! A utility library for dealing with slices and maps that focuses on type safety and performance.
https://github.com/elliotchance/pie

generics go golang slices utility

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πŸ• Enjoy a slice! A utility library for dealing with slices and maps that focuses on type safety and performance.

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# πŸ• `github.com/elliotchance/pie`

[![GoDoc](https://godoc.org/github.com/elliotchance/pie?status.svg)](https://godoc.org/github.com/elliotchance/pie)

[![Build Status](https://travis-ci.org/elliotchance/pie.svg?branch=master)](https://travis-ci.org/elliotchance/pie)

[![codecov](https://codecov.io/gh/elliotchance/pie/branch/master/graph/badge.svg)](https://codecov.io/gh/elliotchance/pie)



**Enjoy a slice!** `pie` is a library of utility functions for common operations

on slices and maps.



- [Quick Start](#quick-start)

- [FAQ](#faq)

  * [What are the requirements?](#what-are-the-requirements)

  * [What are the goals of `pie`?](#what-are-the-goals-of-pie)

  * [How do I contribute a function?](#how-do-i-contribute-a-function)

  * [Why is the emoji a slice of pizza instead of a pie?](#why-is-the-emoji-a-slice-of-pizza-instead-of-a-pie)



# Quick Start



If you are using (or require) Go 1.17 or below, you will have to

[use v1](https://github.com/elliotchance/pie/v1).



`pie` can be used in two ways, the first is to use the regular

[parameterized functions](https://go.googlesource.com/proposal/+/master/design/15292/2013-12-type-params.md):



[Run this program](https://go.dev/play/p/qYaBXPRs3Nk)



```go

package main



import (

    "fmt"

    "strings"



    "github.com/elliotchance/pie/v2"

)



func main() {

    names := pie.FilterNot([]string{"Bob", "Sally", "John", "Jane"},

        func(name string) bool {

            return strings.HasPrefix(name, "J")

        })



    fmt.Println(names) // "[Bob Sally]"

}

```



Or, if you need to chain multiple operations you can use one of:



- [`pie.Of`](https://pkg.go.dev/github.com/elliotchance/pie/v2#Of) - works with any element type, but functions are limited.

- [`pie.OfOrdered`](https://pkg.go.dev/github.com/elliotchance/pie/v2#OfOrdered) - only works with numbers and strings, but has more functions.

- [`pie.OfNumeric`](https://pkg.go.dev/github.com/elliotchance/pie/v2#OfNumeric) - only works with numbers, but has all functions.



[Run this program](https://go.dev/play/p/4IhVbw0koxg)



```go

package main



import (

    "fmt"

    "strings"



    "github.com/elliotchance/pie/v2"

)



func main() {

    name := pie.Of([]string{"Bob", "Sally", "John", "Jane"}).

        FilterNot(func(name string) bool {

            return strings.HasPrefix(name, "J")

        }).

        Map(strings.ToUpper).

        Last()



    fmt.Println(name) // "SALLY"

}

```



You can find the

[full documentation here](https://pkg.go.dev/github.com/elliotchance/pie/v2).



# FAQ



## What are the requirements?



`pie` v2 only supports Go 1.18+. If you have an older version you can

[use v1](https://github.com/elliotchance/pie/v1).



## What are the goals of `pie`?



1. **Type safety.** I never want to hit runtime bugs because I could pass in the

wrong type, or perform an invalid type case out the other end.



2. **Performance.** The functions need to be as fast as native Go

implementations otherwise there's no point in this library existing.



3. **Nil-safe.** All of the functions will happily accept nil and treat them as

empty slices. Apart from less possible panics, it makes it easier to chain.



4. **Immutable.** Functions never modify inputs (except in cases where it would

be illogical), unlike some built-ins such as `sort.Strings`.



## How do I contribute a function?



Pull requests are always welcome.



Here is a comprehensive list of steps to follow to add a new function:



1. Create a new file for your function (tip: copy an existing file can be

quicker). Add your implmentation and comment.



2. Create appropriate tests.



3. If your function accepts a slice, it should also be added to the `OfSlice`

API (see `of.go`).



## Why is the emoji a slice of pizza instead of a pie?



I wanted to pick a name for the project that was short and had an associated

emoji. I liked pie, but then I found out that the pie emoji is not fully

supported everywhere. I didn't want to change the name of the project to cake,

but pizza pie still made sense. I'm not sure if I will change it back to a pie

later.