Re: sph.io libraries

[tantalum <sph@posteo.eu>]

> Neat. Just to double-check - the environment variables of my current 
> process are
> preserved or /tmp/mybin would run with environment consisting only of 
> variables which
> I've explicitly put into execute-with-environment?
the new process receives only the specified environment variables. but 
it should be no problem to pass it a
modified environment from the current process using guiles "environ" 
procedure
   (cons "XX2=LOL" (environ))
working example:
   guile -c '(import (sph process)) (execute-with-environment (cons 
"XX2=LOL" (environ)) "env")'

> the only interface to execve for guile
actually in guile the direct interface to execve is called execle 
(https://www.gnu.org/software/guile/manual/html_node/Processes.html#index-execle).
the "process" version does two more things:
- it adds the program name as the first argument, the usual calling 
convention. would have to be taken care of manually otherwise
- it may search $PATH
- it moves the "env" argument to the front to preserve the order of 
filename and rest-arguments

> Could you illustrate that with some code too? I do not plan to have 
> that many records
> so I'm not concerned with the speed that much :)

the getter/setter definitions where included in the last example. 
setting fields by symbolic name would look like this:
   (define triad (make-record-layout (quote (pid env num))))
   (define t (record triad pid "LOL" 5))
   (record-set! t triad (quote pid) 5011)

the getter/setter definitions could be shortened with a new single 
"define-" form which generates the bindings. i might add that and the 
current library makes this quite easy.
for reference, other record implementations already do this, but these 
implementations regard records as something more complicated.
https://www.gnu.org/software/guile/manual/html_node/rnrs-records-syntactic.html#rnrs-records-syntactic
https://www.gnu.org/software/guile/manual/html_node/SRFI_002d9-Records.html#SRFI_002d9-Records

if you do not want to deal with record-layouts, getters and setters,
you could use vectors which are like arrays in other languages (which 
could be records at the same time)
   (define a (vector 3 4 5))
   (vector-ref a 0)

or hashtables, which are like associative arrays or objects in other 
languages
   (import (sph hashtable))
   (define a (hashtable "a" 1 "b" 2))
   (hashtable-ref a "a")

or association lists, alists, which are lists and similar to 
two-dimensional arrays
   (import (sph alist))
   (define a (alist "a" 1 "b" 2))
   (alist-ref a "a")

(https://www.gnu.org/software/guile/manual/html_node/Association-Lists.html#Association-Lists
  
https://www.gnu.org/software/guile/manual/html_node/SRFI_002d1-Association-Lists.html#SRFI_002d1-Association-Lists)

> I can also have arbitrary number of fields in the record?
yes

> your libraries to be packaged and readily available in my distro 
> repositories
what is your distro?
there is a package for arch linux at least 
(https://aur.archlinux.org/packages/sph-lib-git)
and there is "guix", which seems to become the package manager for the 
gnu system, and might be interesting cross-distro. though as of yet i 
have not figured out how to make a package for it.