Working Practices - Dick Bowman

Currently using Dyalog APL to develop several single-user desktop applications. Used other versions of APL in the past in development groups of varying sizes. Dabbled with variants like J and K. Has also used other programming languages, but...

General Principles:

• APL has its origins as a way to improve communication between people, never forget this.
• Stick to the "functions take their input from arguments and produce results" wherever possible. As a sub-rule, put "controlling parameters" in the left argument and "data" in the right.
• Keep defined functions (and operators) brief.
• Insulate your code from the outside world by localising any system variables that it depends on.
• If you need to include comments to make your code clear, you aren't making your code clear.
• So long as performance is adequate, maintainability is the most important aspect of coding style.

Dyalog Specifics:

• Use control structures to aid clarity. Especially to avoid arrrow-style branching.
• Use in-line dynamic functions to make code simpler.
• Use language constructs which simplify APL, such as the indexing function and dot-syntax. Don't hang onto archaisms like bracket-indexing just because they are familiar.

Current Fads:

• Making increasing use of namespace scripts to hold utility code which is shared across applications.
• Making increasing use of class scripts to handle data.

Detestations:

• Code that is "squished up" to look denser, in particular diamond statement separators.
• Code with comments mingled in and interfering with the real code.
• Error-trapping used to implement application logic.

Disclaimer - this page written on 23 January 2009, preferences and practices may have changed.