The Medley Interlisp Project

@interlisp.org

67 Followers 4 Following

Official account of the open source project to preserve, revive, and modernize Medley Interlisp. This extensible graphical operating and programming environment has roots in Xerox's Palo Alto Research Center (PARC). https://interlisp.org

Screenshot of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and some windows with a white background and a title bar with white text on a black background. The main window is an editor open on the code of a Lisp function.

Screenshot of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and some windows with a white background and a title bar with white text on a black background. The main window is a rich text editor open on a document containing mathematical equations with summation and integral symbols, matrices, and more.

Screenshot of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and some windows with a white background and a title bar with white text on a black background. The main window is a frame delimiting an analog clock application with transparent background.

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a grey background pattern and one window with a white background and a title bar with white text on a black background. The window shows an editor with a text entry field prompting for the name of a file to open.

Screenshot of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and some windows with a white background and a title bar with white text on a black background. The main window, which takes up nearly all of the screen, shows a portion of the graph of a tree-like data structure laid out horizontally.

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a grey background pattern and one window with a title bar with white text on a black background. The title of the window is "Prompt Window" and the inside area, which has a black background with white text, shows the message "Opens a filebrowser window; prompts for pattern". A menu with the highlighted item "FileBrowser" is open at the center of the desktop.

Screenshot of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and some windows with a white background and a title bar with white text on a black background. Some of the windows show scatter plots of random noise functions, other windows the Lisp source of the code that generates the random noise.

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a grey background pattern and one window with a title bar with white text on a black background. The title of the window is "Prompt Window" and the inside area, which has a black background with white text, shows two status messages printed by the system.

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a grey background pattern and one window with a title bar with white text on a black background. The inside area of the window, which has a black background with white text, shows a file directory listing.

Screenshot of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and some windows with a white background and a title bar with white text on a black background. The three main windows show a WYSIWYG text editor open on a document containing a sequence of bitmaps of graphical patterns and desktop backgrounds, along with textual descriptions.

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a grey background pattern and one window with a white background and a title bar with white text on a black background. The window lists the available commands of the Interlisp REPL.

Screenshot of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and some windows with a white background and a title bar with white text on a black background. The main windows show some landscape-like geometric shapes drawn by a turtle graphics program, the Interlisp code of the program, a REPL with expressions to develop the code, and some Lisp documentation.

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a grey background pattern and one window with a white background and a title bar with white text on a black background. The window is a Lisp REPL where the following expression is evaluated and output printed:

4_ PL CAR
DOPCODE : (1 CAR 0 --)
:SETF-METHOD-EXPANDER : CL::CAR-setf-expander
COMPILER::TRANSFORM : CL::transform-CAR
COMPILER::SIDE-EFFECTS-DATA : (:NONE . :NONE)
DOPVAL : (1 CAR)
BYTEMACRO : COMP.CARCDR
CROPS : (A)

Screenshot of the black and white desktop of a 1980s graphical workstation environment. The desktop has a grey background pattern and some windows with a white background and a title bar with white text on a black background. The main windows show some geometric shapes drawn by a turtle graphics program, the Common Lisp code of the program, and the REPL with the expressions to run the program.

Screenshot of the black and white desktop of a 1980s graphical workstation environment. The desktop has a grey background pattern and some windows with a white background and a title bar with white text on a black background. The main window shows the online documentation of the Lisp function APPEND.

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a grey background pattern and one window with a white background and a title bar with white text on a black background. The window shows a graph laid down horizontally of an object-oriented class hierarchy rooted at a class called Tofu.

Screenshot of the black and white desktop of a 1980s graphical workstation environment. The desktop has a grey background pattern and some windows with a white background and a title bar with white text on a black background. The main window is a VT100 terminal emulator running the Lynx web browser on Linux open on the site https://interlisp.org At the left of the terminal is a window showing a virtual VT100 keypad.

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a grey background pattern and two windows with a white background and a title bar with white text on a black background. The bottom window is a Lisp REPL where the following expressions are evaluated, output printed, and values returned:

2/4_ (SETQ LIST.STRUCTURE (LIST 1 2 3 4 5))
(1 2 3 4 5)
2/5_ (ED 'LIST.STRUCTURE)
Editing VARS definition of LIST.STRUCTURE.
LIST.STRUCTURE
2/6_ LIST.STRUCTURE
(1 2 3 (A B C) 4 5)

The top window is an editor that shows a Lisp list structure modified by the above call to the ED function.

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a grey background pattern and one window with a white background and a title bar with white text on a black background. The window is a Lisp REPL where the following expressions are evaluated, output printed, and values returned:

2/5_ (SETQ STACK '())
NIL
2/6_ (PUSH STACK 1)
(1)
2/7_ (PUSH STACK 2)
(2 1)
2/8_ (PUSH STACK 3)
(3 2 1)
2/9_ (PUSH STACK 4)
(4 3 2 1)
2/10_ (PUSH STACK 5)
(5 4 3 2 1)
2/11_ (POP STACK)
5
2/12_ (POP STACK)
4
2/13_ STACK
(3 2 1)

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and one window with a white background and a title bar with white text on a black background. The window is a Lisp REPL where the following expressions are evaluated, output printed, and values returned:

2/4_ (PUTPROP 'WHEN 'MACRO '(ARGS (LIST 'COND (CONS (CAR ARGS) (CDR ARGS)))))
(ARGS (LIST (QUOTE COND) (CONS (CAR ARGS) (CDR ARGS))))
2/5_ (GETPROP 'WHEN 'MACRO)
(ARGS (LIST (QUOTE COND) (CONS (CAR ARGS) (CDR ARGS))))
2/6_ (SETQ FOO 3)
3
2/7_ (EXPANDMACRO '(WHEN (GREATERP FOO 2)
(PRINT "Greater.")
T))
(COND
((GREATERP FOO 2)
(PRINT "Greater.")
T))
NIL
2/8_ (WHEN (GREATERP FOO 2)
(PRINT "Greater.")
T)
"Greater."
T

Screenshot of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and several windows with a white background and a title bar with white text on a black background. One of the two main windows shows the disassembly of the compiled Interlisp function APPEND with the opcodes of the Medley Interlisp virtual machine. The other window is an editor that shows the Interlisp code of the APPEND function.

Screenshot of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and some windows with a white background and a title bar with white text on a black background. The screen shows a scaled down version of the entire remote screen of an Interlisp-D workstation, and a small section at full size which can be moved around.

Screenshot of a Linux terminal window that displays a portion of an Interlisp source file. The code is formatted with syntax highlighting and text colored in white, red, green, and yellow.

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and one window with a white background and a title bar with white text on a black background. The window is a file browser with a main pane listing some files, status and input panes, and a command menu. The file list has a vertical scroll bar at the left edge.

Screenshot of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and several windows with a white background and a title bar with white text on a black background. The windows display Lisp source code, icons, scientific and business charts, a spreadsheet program, a virtual keyboard, and other graphical elements.

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and one window with a white background and a title bar with white text on a black background. The window is a graph editor with an open command menu providing the options Move Node, Add Node, Delete Node, Add Link, Delete Link, Change label, label smaller, label larger, Directed, Sides, Border, Shade, STOP. The window also shows a graph consisting of 2 nodes connected by a link.

Screenshot of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and several windows with a white background and a title bar with white text on a black background. The windows display graph structures with nodes and links and other tools of a hypertext system.

Screenshot of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and several windows with a white background and a title bar with white text on a black background. The windows display a graph structure with nodes and links and other tools of a hypertext system.

A screenshot of a portion of the reference manual of the Interlisp programming language. The portion contains the following paragraph of text (emphasis is in the original):

There have been similar efforts in other LISP systems, most notably the MLISP language at Stanford. CLISP differs from these in that it does not attempt to _replace_ the LISP syntax so much as to _augment_ it. In fact, one of the principal criteria in the design of CLISP was that users be able to freely intermix LISP and CLISP without having to identify which is which. Users can write programs, or type in expressions for evaluation, in LISP, CLISP, or a mixture of both. In this way, users do not have to learn a whole new language and syntax in order to be able to use selected facilities of CLISP when and where they find them useful.

A screenshot of a portion of the reference manual of the Interlisp programming language. The portion contains the following paragraph of text:

Interlisp has been designed to be a good on-line interactive system (from which it derives its name). Some of the features provided include elaborate debugging facilities with tracing and conditional breakpoints (Section 15), and a sophisticated LISP oriented editor within the system (Section 9). Utilization of a uniform error processing through user accessible routines (Section 16) has allowed the implementation of DWIM, a 00-What-!-Mean. facility, which automatically corrects many types of errors without losing the context of computation (Section 17). The CLISP facility (Section 23) extends the LISP syntax by enabling ALGOL-like infix operators such as +. -, *, /, =, _, AND, OR, etc., as well as IF-THEN-ELSE statements and FOR-WHILE-DO statements. CLISP expressions are automatically converted to equivalent lnterlisp forms when they are first encountered. CLISP also includes a sophisticated pattern match compiler, as well as a record package that facilitiates "data-less" programming.

Screenshot of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and some windows with a white background and a title bar with white text on a black background. The main windows show the character table of a font editor and the bitmap of a character of the edited font.

Screenshot of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and some windows with a white background and a title bar with white text on a black background. The main window shows a graph of the hierarchy of the condition system of a Common Lisp implementation.

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and one window with a white background and a title bar with white text on a black background. The window, oriented vertically, is a rich text editor with its area split into three horizontal panes that show different parts of a document.

Screenshot of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and some windows with a white background and a title bar with white text on a black background. The two main, similar windows are divided into panes. One major pane shows a graphical directory tree of a file system. Next to it is a pane with a menu of file management commands.

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and one window with a white background and a title bar with white text on a black background. The window is a Lisp REPL where the following expressions are evaluated, output printed, and values returned:

2/9_ (COMPARELISTS '(A B C D) '(X B E D))
A -> X, C -> E
NIL
2/10_ (COMPARELISTS '(A B C D) '(A D))
(A B C --)
(A D)

NIL
2/11_ (COMPARELISTS '(A B C D E F G H) '(A B C D X))
(A -3- E F --)
(A -3- X)

NIL
2/12_ (COMPARELISTS '(A B C (D E F (G) H) I) '(A B (G) C (D E F H) I))
(A & & (D -2- (G) &) &)
(A & (G) & (D -2- &) &)

NIL

Screenshot of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and some windows with a white background and a title bar with white text on a black background. The main application on the desktop is a documentation browser made from 5 windows attached together by a side. A sixth window of the documentation browser is detached from the others and shows a graphical table of contents tree. A number in red marks each of the 6 windows.

Screenshot of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and some windows with a white background and a title bar with white text on a black background. The main application on the desktop is a documentation browser made from 5 windows attached together by a side. A sixth window of the documentation browser is detached from the others and shows a graphical table of contents tree.

A screenshot of a portion of a computer science research paper that contains the following text:

Interlisp is for experts. The incremental, evolutionary way in which Interlisp developed was not especially conducive to simple interfaces. It was inappropriate to spend a lot of time and effort trying to design the right interface to a new, experimental capability whose utility had not yet been proven. Would the users like automatic error correction? Was the programmer's assistant really a good idea? The inherent complexity of the interactions among some of the more sophisticated tools, such as Masterscope, DWIM, and the programmer's assistant, made it very difficult to provide simple interfaces. In many cases, unification and simplification came only after considerable experience.

Further complexity stemmed from the commitment to accommodate a wide variety of programming styles and to enable the tools to be tailored for many applications. Given the choice of sophistication and generality of tools or simplicity of design, we chose the former, under the assumption that the system was primarily for expert programmers. As a result, mastery of all of the tools and facilities of Interlisp has become quite difficult and initial learning time fairly long. We accept this as part of the price for the system's power and productivity.

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and a window with a white background and a title bar with white text on a black background. The window is a Lisp REPL where the following expression is evaluated:

(RNUMBER "Enter a number" NIL NIL NIL NIL T NIL T)

Above the REPL window is a calculator-type dialog window with the number 1234.56 displayed.

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and a window with a white background and a title bar with white text on a black background. The window is a Lisp REPL where the following expression is evaluated:

(SHOWGRAPH (LAYOUTSEXPR '(S (NP (DET The) (NOUN program (VP (VERB displays) (NP (DET a) (NOUN tree)))))) '(VERTICAL) NIL '(HELVETICA 12 BRR)))

Beneath the REPL window is a graphical window that displays the syntax tree represented by the expression.

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and one window with a white background and a title bar with white text on a black background. The window is a Lisp REPL where the following function call is evaluated:

2/4_ (MENU (create MENU TITLE _ "Delete file?" ITEMS _ '(Yes No) CENTERFLG _ T))

Above the window the function call creates a menu with title "Delete file?" and items named Yes and No.

Screenshot of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and some windows with a white background and a title bar with white text on a black background. The main window is a rich text editor with some text in the buffer. On the title bar of the window are an open popup menu and a submenu with the highlighted item Hardcopy > To a file.

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and one window with a white background and a title bar with white text on a black background. The window is a Lisp REPL where the following expressions are evaluated:

2/9_ (RPT 20 '(PRIN1 "*"))
********************
"*"
2/10_ (RPTQ 20 (PRIN1 "*"))
********************
"*"

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and one window with a white background and a title bar with white text on a black background. The window is a debugger with an open popup menu of commands. The debugger window is divided intwo two panes, a larger one at left for command interaction and a smaller one at right with a stacktrace.

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and one window with a white background and a title bar with white text on a black background. The window is a Lisp REPL that evaluates the following Interlisp expressions and displays their outputs and values:

4_ (SETQ VARIABLE 10)
10
5_ VARIABLE
10
6_ (SETQ VARIABLE 20)
20
7_ UNDO
SETQ undone.
8_ VARIABLE
10
9_ REDO 6
20
10_ VARIABLE
20

Screenshot of a Linux desktop whose area, aside from a horizontal taskbar at the bottom, is mostly taken up by the black and white desktop of a 1980s graphical workstation environment. The workstation desktop has a gray background pattern and some windows with a white background and a title bar with white text on a black background. One of the windows shows the details of a GitHub issue. A web browser window showing the same issue on the GitHub website takes up the lower right quarter of the Linux desktop.

Screen recording of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and one window with a white background and a title bar with white text on a black background. The window is a text editor in which the cursor moves one character or line at a time across the text and lines in the window.

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and one window with a white background and a title bar with white text on a black background. The window is a terminal emulator showing a Linux shell with the output of the Unix ls program.

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and one window with a white background and a title bar with white text on a black background. The window, which takes up most of the screenshot, shows a terminal-like evaluator and command processor that displays some session initialization messages including "Happy Valentine's day, Paolo".

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and one window with a white background and a title bar with white text on a black background. The window is a Lisp REPL that evaluates the following Interlisp expression and displays its output and value:

2/7_ (PRINTOUT T .FONT BOLDFONT "Float:" .FONT DEFAULTFONT , .F10.2..0 1234.567 T)

Float: 0001234.57

NIL

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and one window with a white background and a title bar with white text on a black background. The window, which takes up most of the screenshot, shows a sequence of evaluated Lisp expressions. This is the text of the expressions and their values (the underscore character is the left arrow symbol):
2/5_ A _ 1
1
2/6_ B _ A + 2 * 3
7
2/7_ IF A = 1 THEN 10 ELSE 20
10
2/8_ FOR I FROM 1 TO 10 DO (PRINT I)
1
2
3
4
5
6
7
8
9
10
NIL

Screenshot of a portion of the text of the Interlisp programming language manual which reads: Medley as an Interactive Environment. Medley programs should not be thought of as simple files of source code. All Medley programming takes place within the Medley environment, which is a completely self sufficient environment for developing and using Medley programs. Beyond the obvious programming facilities (e.g., program editors, compilers, debuggers, etc.), the envionrment also contains a variety of tools that "keep track" of what happens. For example, the Medley File Manager notices when programs or data have been changed, so the system will know what needs to be saved at the end of a session. The "residential" style, where you stay inside the environment throughout the development, is essential for these tools to operate. Furthermore, this same environment is available to support the final production version, some parts providing run time support and other parts being ignored until the need arises for further debugging or development.

Screenshot of a portion of the black and white desktop of a 1980s graphical workstation environment. On the desktop with a gray background pattern is one window with a white background and a title bar with white text on a black background. On the title bar is an open popup menu with items named Close, Snap, Paint, Clear, Bury, Redisplay, Hardcopy, Move, Shape, and Shrink. The Close item is selected in reverse.

Screenshot of the black and white desktop of a 1980s graphical workstation environment. The desktop has a gray background pattern and several windows with a white background and a title bar with white text on a black background. The windows display text, bitmaps, graphs, icons, sketches, and other graphical documents and elements.