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Re: Common Lisp solved this problem 20 years ago

This page is part of the web mail archives of SRFI 77 from before July 7th, 2015. The new archives for SRFI 77 contain all messages, not just those from before July 7th, 2015.

Alan Watson wrote:
Per Bothner wrote:

Common Lisp allows a compiler to *assume* / is defined to the standard
/ operation, unless there is a visible re-definition.
Kawa makes more-or-less the same assumpions.
I think that is a reasonable default mode for a compiler.

Unless the compiler has the ability to see into the future, this assumption can be rather dangerous in an interactive system.

Not very, I believe: Redefining a standard function is not a wise thing
to do, and not very common.

Moreso: redefining a standard function (or even a non-standard builtin
function) in a *different* separately-compiled compilation unit (module)
is even more foolish and rare.

(I compile most of Kawa's Scheme code with --warn-undefined-variable
which is very nice for catching errors, and which encourages proper
module imports.  It doesn't preclude a typo or otehr error which
accidentally matches a predefined function, I concede.)

Can you tell me where in the HyperSpec this behaviour is sanctioned? I had a quick look before posting my last message, but couldn't find it.

I can't find it either.  I may have been thinking of: Semantic Constraints
  A call within a file to a named function that is defined in the same
  file refers to that function, unless that function has been declared

But I'm sure Common Lisp allows inlining standard function like (+ ...).
Otherwise how could you possibly generate good code?

If I recall correctly, one of the advances of Dylan over Common Lisp was that that Dylan modules export names and *values* not whereas Common Lisp packages export names. This helps the compiler reason about the value of imported procedures. Bigloo is able to do this too, I think.

Kawa is similar, I think: A module exports a set of bindings.
require-ing the module imports the bindings into the current
(lexical) scope.
	--Per Bothner
per@xxxxxxxxxxx   http://per.bothner.com/