Go Cheat Sheet

References

In a nutshell

Basics

// hello.go
package main

import "fmt"

func main() {
    fmt.Println("Hello Go")
}
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go run hello.go
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Declarations

var foo int // declaration without initialization
var foo int = 42 // declaration with initialization
var foo, bar int = 42, 1302 // declare and init multiple vars at once
var foo = 42 // type omitted, will be inferred
foo := 42 // shorthand, only in func bodies, omit var keyword, type is always implicit
const constant = "This is a constant"
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Functions

// a simple function
func functionName() {}

// function with parameters (again, types go after identifiers)
func functionName(param1 string, param2 int) {}

// multiple parameters of the same type
func functionName(param1, param2 int) {}

// return type declaration
func functionName() int {
    return 42
}

// Can return multiple values at once
func returnMulti() (int, string) {
    return 42, "foobar"
}
var x, str = returnMulti()

// Return multiple named results simply by return
func returnMulti2() (n int, s string) {
    n = 42
    s = "foobar"
    // n and s will be returned
    return
}
var x, str = returnMulti2()
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Funcs as values and closures

func main() {
    // assign a function to a name
    add := func(a, b int) int {
        return a + b
    }
    // use the name to call the function
    fmt.Println(add(3, 4))
}

// Closures, lexically scoped: Functions can access values that were
// in scope when defining the function
func scope() func() int {
    outer_var := 2
    foo := func() int { return outer_var}
    return foo
}


// Closures
func outer() (func() int, int) {
    outer_var := 2
    inner := func() int {
        outer_var += 99 // outer_var from outer scope is mutated.
        return outer_var
    }
    inner()
    return inner, outer_var // return inner func and mutated outer_var 101
}
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