About srfi-58

[nalaginrut]

hi guys!
I checked out the slib and realized most of the part of slib we do have
it in our core/modules. 
Unfortunately, "prime" is not in the feature list of slib when I run
slib:feature. But I need it, then I try to port it to Guile directly.

And I encountered something "A:fixN32b" can't be found. I think this
"prime" needs srfi-58. But I remember Guile has it's own array
notations, srfi-58 will introduce another one.

So let me raise a topic about the proper implementation of srfi-58. If
we have something useful in this thread, we may do it.
In my opinion, we have to add a global variable to check if the user
used srfi-58, and scm_read_array could call a brand new
scm_i_srfi_58_read_array if it's true. 
But I don't think introduce a global variable is a good way. Maybe add
new read-opts is better? And if we do it in the C level, it's not so
interesting to implement the array parser. 

Anyone provide better solution? Any other consideration about srfi-58 is
welcome. ;-)