this paper is a discussion of the expressive power of various languages, but efficiency is always a concern, especially with constructs that must examine large collections. It should therefore be pointed out that the expression of a loop in terms of mapping functions, function closures and recursive function-calling does not mean inefficiency. It is well-known how to compile "tail-recursive" functions into highly efficient iteration [Steele78], and high quality Lisp systems have been "open-coding" mapping functions for at least 20 years.

This paper discusses work which is a continuation of [Baker90]. Our birth control scheme for objects of LP type bears a strong resemblance to Barnes'es scheme for controlling access to a resource [Barnes89,9.3]. Barnes does not export a nesting generic unit to handle deallocation, however.

Many modern programming languages offer a facility for "inlining" designated procedure and function calls, but this process is not well defined in most language standards documents. We offer a model for inlining which has the property that the resulting code does not depend upon the presentation of the order of function definitions, and which also provides a finite and consistent interpretation for the inlining of mutually recursive functions. Finally, when used on "tail-recursive" functions, our model of inlining provides for the equivalent of "loop unrolling". Introduction Many programming languages---e.g., Fortran, Ada, C++, Common Lisp---offer a facility for "macro-expanding" procedure and function calls, so that the operations of the procedure or function are performed "in line" with the other operations of the calling procedure rather than being performed "out of line" within a "closed" subroutine [Allen80] [Harrison77]. The goal of such an integration is to improve execution ...