A proposal for blocks and exits in APL
Jim P. Fiegenschue · ACM SIGAPL APL Quote Quad · 1987
A simple method of expressing structured programming constructs is proposed which avoids the need for the large number of keywords found in most structured languages. With this simple method, a countably infinite series of constructs may be formed. It is demonstrated that all conventional structured programming constructs may be expressed using only the constructs corresponding to -1, 0, 1, and 2.