Installing a wrapper guile script in <out>/bin

[elaexuotee]

Hello Guix,

Writing package definition, I have need of a non-trivial wrapper script that
decides how to execute the installed binary. How do I accomplish this?

With my vague understanding, I am envisioning writing a gexp directly in the
install phase and would like to somehow reify this into a guile script and
install that file under <out>/bin. Is this correct, at the high level?

More specifically, the package I have builds separate libraries for CPUs with
AVX, AVX2, and no AVX support. Since build-type isn't sufficiently specific to
distinguish such CPU features, I have, so far, opted to just build all three
libs and stuff them under <out>/lib/<foo>.

My idea is to have the linker script check CPU features at runtime (by parsing
/proc/cpuinfo or something) and executing the binary with the parameters to
load the correct binary.

Perhaps there is a better overall approach?

Appreciate your thoughts!