Interpreter

An interpreter is a program which reads a story file and presents the game contained inside that file to the player. The interpreter itself is not part of the game, although it may provide shortcuts to make the playing more convenient. Many interpreters allow the player to enter commands (i.e., LOOK or GO NORTH) by pressing a single key combination (a "hotkey"). In addition, some interpreters allow the player to tweak display options to his liking (i.e., fonts and colors).

The interpreter's function in interactive fiction is akin to that of a movie projector in motion pictures. It translates the "raw material" of the work into a more palatable format for humans.

Technically, interpreters are usually virtual machines. They don't care about the higher-level language used to create the compiled code that is run on them. The Z-machine, for example, is usually programmed with Inform, but Infocom, who created it, used a compiler and language called ZIL. Glulx is similar to the Z-Machine, but designed to remove some limitations of that design, and also is typically programmed with Inform.

Interpreters by Platform

One of the advantages to the Virtual Machine concept is cross-platform compatibility. A story-file only needs to be written once and can be run on any computer on which an interpreter exists for similar story files. This makes the interpreter the only piece of software that needs to be written for a specific platform.

There are interpreters for nearly every modern (and many not so modern) computing platforms.

Some interpreters are usable for most formats of interactive fiction.

• For Mac OS X there is Spatterlight
• For Windows and Unix there is Gargoyle

There is a matrix of interpreters for finding a useful interpreter for a particular platform.

Types of Interpreters

• Z-machine
  This is the one that Infocom invented in the late 1970s.
• Glulx
  This is something of a redesign of the Z-Machine with many new features.
• TADS
  This is a system designed by Mike Roberts in the late 1980s. TADS2 is well established and TADS3 is a redesign that is currently in beta.
• Hugo
  This is a system designed by Kent Tessman, somewhat inspired by Inform and TADS but designed to be easier to work with.