Recent advances in programming language design
DAVID W. BARRON · ITNOW · 1975
Readers who do not follow the columns of Datamation will have missed some significant contributions to language design. The first of these appeared in the December 1973 issue, which had structured programming as its theme. Under the title ‘A Linguistic Contribution to GOTO-less programming’, R. L. Clark of the Rand Corporation introduced a novel concept: the COME FROM statement. In its simplest form, COME FROM causes the statement identified by to be executed before the statement immediately following the COME FROM in the text. Such out-of-line execution is, of course, precisely analogous to the ‘execute’ instruction that features in some machine codes. The unconditional COME FROM is no more than an amusing oddity: the power of the construction is seen in its extensions, the conditional, computed and assigned COME FROM statements. Thus IF COME FROM causes out-of-line execution of the statement identified by whenever the condition is true. As an example, Clark shows that the programs in Figures 1( a ) and ( b ) are equivalent.