Medley provides a rich software development environment, including a debugger, a list structure editor, a file package, a compiler, text-editing facilities, and other useful tools. With any interactive computer language, the user interacts with the system through an "executive," which interprets and executes commands. Medley includes three such executives: Common Lisp, Xerox Common Lisp, and Interlisp. Medley is a programming system, containing not only a programming language but also many predefined programs and specialized programming tools.
Medley's interactive window-based debugger automatically appears when an error occurs. You can enter the debugger through a program execution error, a user-entered keyboard interrupt, or a programmer-specified break. When execution is halted for one of these reasons, the user can reset the system and unwind the stack, or enter the debugger. The break window is an executive window; you can perform any activity here that you can in other executive windows, including looking at the program's current state, changing data structures, evaluating expressions changing a function, and calling the editor. These break facilities, familiar to Interlisp users, are now in the common Lisp executive as well.
The programmer's assistant. This tracks the user's actions during a session, allowing them to be replayed, undone, or altered. The most common interaction with the programmer's assistant occurs at the top level read-evaluate-print loop or in a break, where the user types in expressions for evaluation and sees the value printed out.
The file package and compiler. The file browser provides a convenient user interface for manipulating files stored on a workstation or file server. The makefile option in the file package lets you compile an entire file. You can compile individual functions using the compile command for functions in memory, the Tcompl command for definitions stored in files, or the Recompile command for a combination of in-memory and file definitions. Medley also supports block compiling.
Structure and text editors. Medley offers a choice of structure (list) editors. Dedit and Sedit. When loaded, the Dedit library utility becomes the default structure editor. Sedit does not have the type-in buffer of Dedit; it automatically places Lisp structures that the user fills in by selecting a character or a structure. Sedit recognizes Lisp functions such as single quotes, back quotes, and commas. It automatically adds spaces to maintain legal structures. Medleys Tedit supports multiple fonts, embedded graphics, and document formatting. Figures created with the drawing program, Sketch, can also take screen snapshots.
Notecards tool collects, organizes, and presents hypermedia information. Many cards can be displayed at once, and each can contain text, sketches, or scanned graphics. Cards are connected by typed links and stored in "file boxes." The Spy tool lets you identify program bottlenecks
Venue's Lisp Object-Oriented Programming System
Objects give you a lot of power, but they're not the whole answer. Sometimes, other ways of looking at a problem will work better. At times, plain procedural programming is best. Other times, you'll want to trigger actions in response to changes in variables' values. Yet other times, you'll want to use rules to capture domain specific knowledge. LOOPS gives you all of these in one coherent package. LOOPS also gives you development tools that really help you while you work. You'll want to keep track of the classes and objects you've created. LOOPS' browsers let you do that. You'll want to watch your rules in operation to find out where they're going awry. LOOPS' rule auditing facility lets you do that.
Big systems often have many objects that start out the same, and slowly diverge as the system runs. Normally, you'd have to start off with completely separate objects, at a tremendous cost in memory. LOOPS lets you start with only a single real object. All the others are tiny "virtual copies" of that one. Each copy grows only as you change the values of its instance variables. the effect is the same as having many independent objects, without the memory cost.
The classes and objects you create are the same blocks LOOPS is built our of. So the classes you create can be combined with LOOPS itself to extend its power. You wind up with a system that speaks your language and has tools to fit your needs-and your specialized tools have become part of LOOPS, so its power is brought to bear to solve your problem.
"Medley is and has been a system before its time. Through the debuggers, the graphics and window systems, and the organized structure of the underlying Lisp systems, Medley provides a marvelous tool that creates enthusiasm and motivation for programmers, applications builders, application users, teachers, and students alike."-Patrick Goddi and Anne M. Keuneke
Jill Marci Sybalsky
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