The first Go program (2013) | Hacker News Reader

The first Go program (2013)

blog.golang.org

72 pointsGurrewe13 comments

I find it amusing that this first program in Go is for parsing an Lisp-style S-Expression, given that this has nothing to do with Go's syntax.

Most programs do something other than parse the syntax of the language they are written in. A programming language really only needs to be self-hosting once, and that may be an early program, but it seems unlikely it is the very first.

Yes, but most programming languages are around for a few years before someone tries to use them to implement another language.

Toy s-expression parsers are on an equal footing with "Hello World" regarding their complexity.

It's not like they tried to implement some full Lisp/Scheme.

One of my backlog-projects is an implementation of Common Lisp in Go, which can be easily used to provide an embedded scripting language for Go programs (and, eventually, an excuse to write 'Go' code which is actually Lisp). It's one of those crazy ideas I'll probably never get to, but it sure would be fun.

I have ~that. Of course it's not Common Lisp though (so, Hubris Lisp?). Notably you have to statically register the Go functions you want to be callable from the Lisp side, because otherwise they might not even be present in the compiled binary (and even if they were, I don't think Go will help you find an arbitrary function by name at runtime). I've used it much more as a normal 'shebang' shell scripting language (even ""webapps"" via CGI) than an embedded one so far... mainly through lack of ideas that call for such a thing.

>and even if they were, I don't think Go will help you find an arbitrary function by name at runtime

You'd be surprised:

https://golang.org/pkg/reflect/#Value.MethodByName

That's about methods and not functions ;) Yes indeed, if you are partying in the context of a specific value, you can use that reflection. My language is not "OO"-aware though. Maybe after I give the embedded mode more real world use then that aspect will be unavoidable.

A, yes. In that case you could expose all the functions you want in advance, in some map that's accessible by (string) name.

    // Static
    
    err = rootEnv.DefineForeignProcedure("sprintf", fmt.Sprintf)

    # Runtime

    (let x 2
         (sprintf "%d cubed is %d"
                  x
                  (pow x 3)))

    => "2 cubed is 8"

Yep, that's what I was talking about.

This seems relatively complex for being the first Go program. I suppose they wanted to test something non-trivial which took advantage of most of the implemented language features. I guess I was expecting something closer to a hello world program.

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