String manipulation with extended Euler

Abstract

WITH MANY of the general programming languages available today inadequate in their string handling capabilities, users who wish to process text have to resort to unnatural extensions to languages such as FORTRAN and ALGOL 60, in which string manipulation is often provided by subroutines or procedures from a library. There are, of course, languages specifically designed to meet the needs of those who wish to pursue non-numeric programming activities languages such as SNOBOL IV [1] and SNAP [2] but these may either fall short on numerical or structural capabilities, or not be implemented on the user's machine. Some languages, designed for interactive use, such as SCAN [3], are usually machine dependent. A few more recent languages, such as ALGOL W [4] and ALGOL68 [5], although they have good string manipulative capabilities built into them, are not always available to some sections of the community (ALGOL W is orientated to IBM 360/370 machines, ALGOL 68 has not yet become readily available on many ranges of computers). The general programming language EULER [6], proposed as a successor to ALGOL 60, had many of the characteristics of that language. It also had many new features that need to be described in more detail. The language 'is a block structured language, where a block contains declarations and statements enclosed within begin and end. The essential difference between blocks in EULER and blocks in ALGOL 60 is that EULER blocks, which can return a usable value, can be a valid constituent of an expression, for the value of the block is the result of the last expression evaluated before leaving the block.