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[Caml-list] handling forward references in a compiler
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Date: | 2004-05-25 (11:00) |
From: | skaller <skaller@u...> |
Subject: | Re: [Caml-list] handling forward references in a compiler |
On Tue, 2004-05-25 at 19:52, dido@imperium.ph wrote: > I'm writing a compiler for a language that allows undeclared forward > references in OCaml, and I'm just wondering how one is supposed to > handle these sorts of things without resorting to imperative features or > multiple passes. What's wrong with multiple passes? Felix uses many passes. It doesn't backpatch though. I make a hash table keyed by a fresh integer with data of each definition, and a set of hash tables representing scopes, keyed by the identifier with data the integer. In the next pass, I bind uses by looking up the name in the scopes to find the integer. The effect is that scopes are all mutually recursive, and lookup is always random access within a scope: forward reference declarations are never needed because the whole scope is always searched. For example: fun f():int { return g(); } fun g():int { return f(); } works just fine. You can also write: val x = y; val y = 1; which also binds just fine .. although it doesn't do anything sensible at run time. -- John Skaller, mailto:skaller@users.sf.net voice: 061-2-9660-0850, snail: PO BOX 401 Glebe NSW 2037 Australia Checkout the Felix programming language http://felix.sf.net ------------------- To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ Beginner's list: http://groups.yahoo.com/group/ocaml_beginners