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Introduction to Muddle

Background

Muddle, later renamed MDL, was a programming language created by the Dynamic Modeling group (also known as the Programming Technology Division) at MIT. The most famous application written in this language is the Zork interactive fiction game. The influental CLU programming language was bootstrapped from Muddle.

Muddle is a dialect of Lisp, but with the distinct difference that forms are bracketed by < and > instead of parentheses. ( and ) still denote lists and are occasionally present in the language syntax. The language is case sensitive, and all standard names must be entered in upper case. To submit an expression to the interpreter, type the Escape key which echoes as $.

Interpreted Example

A common way to develop applications in Muddle, is to build a program in the interpreter and write out a SAVE image file. This file can later be recalled using RESTORE.

To make a "hello world" application, create a file called HELLO MUD with this content:

<DEFINE HELLO ()
  <PRINC "Hello, muddled world!">
  <TERPRI>
  <QUIT>>

<DEFINE SAVE-IT ()
  <COND (<=? <SAVE "HELLO SAVE"> "SAVED"> <QUIT>)>
  <HELLO>>

HELLO is the main program which prints a message and terminates. SAVE-IT is used to create a SAVE file and arranges to call HELLO when it's restored.

Now start :mud55 and type <FLOAD "HELLO MUD"> and Escape. Next, type <SAVE-IT>Escape. It should look like this:

:mud55
MUDDLE 55 IN OPERATION.
LISTENING-AT-LEVEL 1 PROCESS 1
<FLOAD "HELLO MUD">$
"DONE"
<SAVE-IT>$
:KILL

A HELLO SAVE file has been created with the HELLO procedure in it. To run it, start :mud55 again and type <RESTORE "HELLO SAVE">:

*:mud55
MUDDLE 55 IN OPERATION.
LISTENING-AT-LEVEL 1 PROCESS 1
<RESTORE "HELLO SAVE">$
Hello, muddled world!

:KILL

The sample program can be found in the HELLO directory.

Compiled Example

Any serious Muddle program would be compiled. To do this, invoke the PCOMP program which is Muddle with the compiler built in. Then call the procedure FILE-COMPILE to compile the source file. The compiler will work in the background.

:pcomp
MUDDLE COMPILER NOW READY.
<FILE-COMPILE "HELLO MUD">$

Toodle-oo.
:PROCED
*
Job PCOMP wants the TTY

When the compiler is done, it leaves the compiled file HELLO NBIN in your directory. Start Muddle again, and this time load the compiled file. Then make the SAVE file:

:mud55
MUDDLE 55 IN OPERATION.
LISTENING-AT-LEVEL 1 PROCESS 1
<FLOAD "HELLO NBIN">$
"DONE"
<SAVE-IT>$
:KILL

The new SAVE file can be restored like before, but it can also be used to make a standalone executable. This is done by having the MIDAS assembler process the file SUBSYS MAKER. The assembler will request information to locate your SAVE file. The file name is HELLO SAVE, which is the "Subsystem name" and "Second Name" below. The directory is the last question about the "Sname".

:MIDAS TS HELLO_MUDSYS;SUBSYS MAKER
Muddle Subsystem Bootstrap
Type in Subsystem (Save File) name: HELLO
Type Y if you wish to have Save File directly restored: Y
Type Second Name of Save File: SAVE
Type Sname of Save File: HELLO
:KILL

This will produce an exectutable file called TS HELLO.

More Information

For more information, see these documents: