ALGOL 68 was complex, and posed difficulties for both

implementors and users. It featured structural equivalence;

automatic type conversion ("coercion") including

dereferencing; flexible arrays; generalised loops

(for-from-by-to-while-do-od), if-then-elif-fi, an integer case

statement with an 'out' clause; skip and goto statements;

blocks; procedures; user-defined operators; procedureparameters; concurrent execution (cobegin/coend);

semaphores; generators "heap" and "loc" for dynamicallocation. It had no abstract data types or separatecompilation.