This is the third volume in a four-volume collection devoted to reusable software components (abstract data types) implemented in Modula-2. Volume 1 discusses stacks, strings, and sets, volume 2 describes single and doubly linked lists, queues, and deques, and volume 3 presents trees and graphs.

The two preliminary chapters consist of Specification, which describes the specification format used, and Module Guide, which identifies the role of each module and its secrets. The author concisely describes each procedure abstraction using a format developed by Liskov and Guttag [1], which consists of the following elements: Requires, which lists constraints that insure the defined behavior, Where, which describes arguments of procedural parameters, Modifies, which lists all modified input arguments, Effects, which describes the procedure purpose and the effects visible as normal behavior, and Signals, which identifies exception conditions and behavior under those conditions.

Module Import Graphs, which show the hierarchical structure of the modules through the imports relation, support the Module Guide. This is a graphical depiction of the static dependency between the modules.

The documented modules were developed using Bob Campbell’s MPW Modula-2 compiler for the Macintosh. However, the source code will also be available on diskette for the SemperSoft and MetCom Modula-2 compilers for the Mac and for the TopSpeed, Logitech, and Stony Brook compilers for the IBM PC and compatibles.

These volumes do for Modula-2 what Booch did for Ada. With the availability of source code libraries for frequently used components of computer science, there is no longer any reason or excuse for reinventing the software wheel.