[R6RS] Flonum operators and modules

[Marc Feeley]

It was suggested at the Snowbird meeting that it might be interesting 
to add flonum specific operators such as fl+, fl<, etc to Scheme (where 
all arguments and numeric results are inexact reals).  I assume this is 
still on the table and will be discussed at the Boston meeting.  I'm 
favourable to this idea in principle but I believe these operations 
should be put in a library module named "fl".  Moreover, there should 
be a "fully qualified" notation of the form

     module.ident    (or module:ident, or module#ident it doesn't matter 
to me)

that combines the operations of locally using the named module, 
importing ident from that module, and accessing ident.  This would lead 
to code like

    (define (ffib x)
      (if (fl.< x 2.0)
          1.0
          (fl.+ (ffib (fl.- x 1.0)) (ffib (fl.- x 2.0)))))

Note that the module.ident notation can be easily implemented through a 
global environment, so there is very little to add to existing 
implementations of Scheme.  There would be some changes needed to the 
module system so that an identifier of the form module.ident is treated 
specially.  A definition of an exported variable "bar" in module "foo" 
would translate to a definition of the global variable "foo.bar".  If 
"bar" is not exported then a unique name could be generated, or a 
special name like "foo..bar" would be used.  The advantages are that it 
simplifies integration of the module system in existing implementations 
of Scheme and it simplifies the debugging process because the debugger 
can use fully qualified names to name procedures/variables in a module 
and it allows the user, when in the debugger, to easily access or call 
procedures in a specific module (at least the exported ones, but 
possibly the non exported ones if the "foo..bar" notation is used by 
the module system).  It does mean that a program cannot contain more 
than one (top-level?) module of a given name (Kent: is this 
one-top-level-module-of-a-given-name constraint part of your module 
proposal?).

Marc