Tags: GoLang Example Code

Go Language and Functional Programming

There is a cool new language on the block, coming from The Google courtesy of (among others) Rob Pike and Ken Thompson. The language is called Go (and the debugger is called Ogle, so put ‘em together for a secret message) and it attempts to be both a low-level, type-safe, compiled language, like C, while being garbage-collected, concise, with high-level structures and idioms like Python and Javascript. There are a lot of things to like in it, and I am exploring what it can and cannot do.

My first question was whether you could use it for functional programming, i.e., are functions first-class objects that can be passed to other functions, returned from functions, stored in variables, etc. This wasn’t in the FAQ or the Language Design FAQ, but there were some hints of it in the description of channels, so I went ahead and wrote my own tests to see if it would work.

package main

import fmt "fmt"

type Stringy func() string

func foo() string{
        return "Stringy function"
}

func takesAFunction(foo Stringy){
    fmt.Printf("takesAFunction: %v\n", foo())
}

func returnsAFunction()Stringy{
    return func()string{
        fmt.Printf("Inner stringy function\n");
        return "bar" // have to return a string to be stringy
    }
}

func main(){
    takesAFunction(foo);
    var f Stringy = returnsAFunction();
    f();
    var baz Stringy = func()string{
        return "anonymous stringy\n"
    };
    fmt.Printf(baz());
}

This compiled and ran, giving the right output, so it looks to me like functional programming is indeed possible in Go, and on the Effective Go page we learn, “In Go, function literals are closures: the implementation makes sure the variables referred to by the function survive as long as they are active.” So that’s kind of cool.

Go also has rich, high-level concurrency support similar to Erlang, several features that prevent random memory from being read or written, and both strings and maps (dictionaries, hash tables) are built-in datatypes. It has a small, but powerful standard library.

One puzzle down, several to go. I still want to explore how I can talk to Cocoa from Go (for GUIs), how to wrap libraries such as libxml2 and cairo for Go, and basically how to map more Python/Javascript library goodness into Go’s world.

I have smaller questions too: can I add methods to existing types? How do I load the contents of a URL? It’s looking good so far! Tune in next time for more exploration.