Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!rutgers!rochester!pt.cs.cmu.edu!a.gp.cs.cmu.edu!koopman From: koopman@a.gp.cs.cmu.edu (Philip Koopman) Newsgroups: comp.lang.forth Subject: Strongly typed Forth?? Message-ID: <3067@pt.cs.cmu.edu> Date: 21 Sep 88 15:05:16 GMT Sender: netnews@pt.cs.cmu.edu Organization: Carnegie-Mellon University, CS/RI Lines: 26 A year or two ago, Hans Niewenhuser (I *know* I spelled it incorrectly!!) gave an argument at the Rochester Forth Conference that Forth has the potential to be a strongly typed language. The argument for this is based on the use of CREATE ... DOES> ... (or whatever your dialect calls it). In most implementations, the DOES> re-points the code field to the DOES> ... clause code. So, if you make each kind of variable with its own DOES> field, then each kind of variable has a different CFA value. The CFA value then contains the type information. A clever compiler (especially an infix expression processor extension) can exploit this typing information to do automatic type conversions. For example: : VARIABLE CREATE 0 , DOES> ; : DVARIABLE CREATE 0.0 D, DOES> ; VARIABLE VA VARIABLE VB In this example, VA and VB will have different CFA values. Phil Koopman koopman@maxwell.ece.cmu.edu Arpanet 5551 Beacon St. Pittsburgh, PA 15217 PhD student at CMU and sometime consultant to Harris Semiconductor.