Re: s48_extract_string?

   Date: Tue, 3 Mar 2009 07:17:15 -0500
   From: Donald Allen <[email protected]>

   So in "Command Programs", commands, normally typed at the
   REPL in ",command args" syntax are now in s-exp syntax
   and s-expressions need to be wrapped in run in order to
   be evaluated properly?

"Command Programs" are just Scheme programs that have access
to procedures that correspond to the commands.  The 'run' is
needed to evaluate expressions in the current user
environment.  If you just want to evaluate them in the exec
package you don't need the 'run'.

  > ,exec (let ((a '(2 3))) (apply + a))
  5
  > 

When your program

  (open 'external-calls)
  (open 'load-dynamic-externals)
  (load-dynamic-externals ...)

gets evaluated in the 'exec' package, 'open' is a procedure
that, like the ,open command, opens a package in the current
user package.  'load-dynamic-externals' is free in the
'exec' package, which is where the program is running.  It's
bound in the user package, and
  (run '(load-dynamic-externals ...))
is one way to evaluate the expression in that package.

   When there's REPL code that already distinguishes quite
   nicely between commands and s-expressions?  Why wasn't
   the latter used to read from a file, so that "command
   programs" would have the same syntax as accepted by the
   REPL, instead of introducing this grossly underdocumented
   new command language?

It isn't a new language at all, which is why there is no
documentation for it.  The language is Scheme, with some
additional functions added.  I believe that Scheme is
adequately documented.  It may be that the additional
functions in the exec package could use additional
documentation, but that doesn't seem to be the problem
you are running into.
                                 -Richard Kelsey