Computer versions of APL (A Programming Language) evolved from the algorithmic notation of K. E. Iverson. APL was implemented as an interactive language by Iverson, Falkof and others at IBM as APL 360. APL is similar to algebraic notation, but interprets expressions right to left. APL uses special symbols. The Text Keyboard used for APL in MYSYS and MYNET. Some comparison of APL with other traditional computer languages is given in APL is not A Programming Language. Also in Iverson _ APL + J
Four APL*PLUS interpreters were available for small computers at UNB. APL/PC, originally for 8088 and similar machines, APLII with the same features as APL2 by IBM requires a 80386 or higher. APLIII similar to APLII but for Windows. APL+Windows. These have now been discontinued, but various versions are available commercially. A number of APL workspaces are included in NUNET. See the Tools page.
APL uses common algebraic, Greek letters, & other symbols to represent useful primitive functions and operators..
Consult texts such as 'APL IS EASY', 'APL an interactive approach' by GILMAN and ROSE, for the basics of APL programming. See the APL*PLUS documentation for a complete listing of functions, features and system supplied workspaces.
When not in a defined function (fn) you are in APLie. When 'Enter' is keyed in APLie the line marked by the cursor on the computer display is interpreted. This is referred to as Entering. If the line follows APL syntax rules, it is executed and the result displayed, otherwise an error message describes why the interpretation failed. APL runs in a session manager and the default is APLie.
Functions behave like verbs, variables and constants like nouns, etc. They can be combined as in math. E.g. 3+4 is a sequence of the constant 3, primitive + and constant 4. Enter 3+4 on one line, the result 7 will show on the next.
This works with a+b, where a and b are algebraic variable names. Values must be assigned to a and b for APL to interpret the a+b expression, otherwise a 'value error' will result. a3 and b4 assigns values. Interpreting a+b will then produce the same result as 3+4. This is a dyadic or two variable use of the primitive +. The algebraic y=a+b means the same as ya+b in APL. Any expression written in correct APL syntax and where the required information is complete will be executed when entered. Expressions can be up to 255 characters long. APL does not have precedence rules like algebra and relies on the right to left sequence and parentheses for the order of execution.
End to date: 070828, ams