Let me make a distinction between values known a fortiori, like those of the keywords or reserved words of a statement-level language and classes of values defined by initial letter, length in characters, or the like.
It is correct that IBM REXX treats single-letter identifiers differently from longer ones. MC has said so in two other fora. Organizing a symbol table/dictionary by identifier length is an old idea. For example, the Lowry-Medlock FORTRAN H compiler, to which I have referred here before, kept one-, two-, three-, four-, five- and six-character identifiers is separate subdictionaries. (The feasibility of this scheme rerflects a FORTRAN constraint thasty in turn reflects the architecture of the IBM 704 and its sequelæ. An identifier of at most six six-bit characters could always be kept in a 36-bit register.) There is strong evidence, derived from studies of large samples of source programs, that single-character identifiers are both fewer and referenced much more frequently than longer identifiers, at least in languages in the FORTRAN-ALGOL tradition. This probably reflects the contaminating influence of mathematical notation. (I have more than once been dismayed to see that COBOL programmers, who are largely free of this malign influence and who do not use subscripts/indices a lot, often give them long identifiers like 'in-batch-subgroup-index-position' when they do use them.) John Gilmore, Ashland, MA 01721 - USA ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
