What's the technical definition for "routine"?

Question

I'm studying lisp language (to do lisp routines) and in a general context i know what's a routine, but in a technical context i can talk about it, because i'm starting to learn routines now. So, what's the real definition of routine? (i've already "googled" this but didn't find anything)

Answer 1

The term routine derives from subroutine, which is a more common term in languages like BASIC where one actually creates SUBroutines. (BASIC actually had a difference between a SUBroutine and a FUNCTION, but nevertheless...)

From the Wikipedia entry:

In computer science, a subroutine (also called procedure, function, routine, method, or subprogram) is a portion of code within a larger program that performs a specific task and is relatively independent of the remaining code.

As the name "subprogram" suggests, a subroutine behaves in much the same way as a computer program that is used as one step in a larger program or another subprogram. A subroutine is often coded so that it can be started ("called") several times and/or from several places during a single execution of the program, including from other subroutines, and then branch back (return) to the next instruction after the "call" once the subroutine's task is done.

Different languages/environments/eras have different ecosystems and thus different terms to describe the same general concept. I generally only use the term function (or method in an "OOP" environment) these days.

Happy coding.

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For fun I have Community Wiki'ed. The list below is hopefully to cover which term(s) is (are) "correct" (widely accepted) to use in a given language to mean routine. Informally routine is used in context of all the languages below so it should be omitted unless it is the defacto term used. Feel free to add, correct, and annotate as appropriate.

• C - function
• Java - method. While function is also often used, the term function does not appear in the Java Language Specification.
• C# - method and function. In the specification, functions refer to function-objects and anonymous functions. They are not the same as methods, which are members of types (classes or structures). Also consider delegates.
• JavaScript - function or method. Methods are functions accessed via a property of an object.
• Haskell - function. This is the accepted terminology.
• Scala - function or method. Method if def member of type, functions are first-class values.
• BASIC - function or subroutine. Subroutines do not return values. Supports call-by-reference.
• FORTRAN - function or subroutine. Subroutines do not return values. Supports call-by-reference.
• LISP - function. DEFUN -> DEfineFUNction, all forms are valid expressions. Also consider macros, which are not themselves functions but are arguably routines.
• VHDL - subprograms: functions and procedures. Procedures have no return value.
• SmallTalk - method
• Python - method
• Ruby - method (often interchanged with function? lambdas/Procs may be considered different?)
• Perl - function and subroutine. There is only one form to declare a function/SUBroutine so there is no distinction w.r.t. return values. Using method (for object-bound functions) seems less prevalent than in other languages.
• Pascal - procedures and functions
• Ada - procedures and functions

Answer 2

You can't find a technical definition because there isn't a technical definition specific to lisp. A 'routine', outside of vaudeville, is just another name for a function. While it's been many years since I programmed in Lisp full-time, no one ever used that term in any formal way, or even used it commonly. We talked about 'functions', 'macros', and 'forms.' If someone said, 'oh, there's a routine to calculate how many apples in a pie' it was perfectly informal.