[bug#39317] [PATCH v2] gnu: Add go 1.13.7.

[Leo Famulari]

On Thu, Jan 30, 2020 at 04:19:48PM +0100, Jakub Kądziołka wrote:
> * gnu/packages/golang.scm (go-source): Factor out the source fields of
>   all the go versions into a new helper function.
>   (go-1.4, go-1.12)[source]: Use go-source.
>   (go-1.13): New variable.

> +(define (go-source version hash)
> +  (origin
> +    (method url-fetch)
> +    (uri (string-append "https://storage.googleapis.com/golang/go";
> +                        version ".src.tar.gz"))
> +    (sha256 (base32 hash))))

There is always a trade-off between readability and time spent writing
code with this kind of helper function. Since there are only 3 Go
compiler packages, I'm not convinced it's necessary here.

We should switch to building the 1.4 bootstrap Go from Git — they make
changes in Git but don't always release a tarball. Then there would only
be two "current" Go packages.