The Loop Facility


destructuring list

A list whose individual elements can be assigned a value from a corresponding list of values.

exclusive limit

A limit that does not include its endpoints.

inclusive limit

A limit that includes its endpoints.


The process of executing an expression or a series of expressions one or more times.


A symbol preceded by a colon (:mode,:value, and so forth).

lexical scope

A scope that allows forms to be accessed only by expressions that lie textually within the same construct in which the forms were established.


An iterative series of expressions.

loop body

The part of the expanded loop form that contains forms that are executed during iteration, such as iteration termination tests and variable stepping.

loop epilogue

The part of the expanded loop form that contains forms that are executed after iteration terminates, such as code to return values from the loop.

Loop Facility

An extensible iteration mechanism that provides you with a variety of ways to iterate and to accumulate values in a loop.

loop keywords

Symbols that are recognized by the Loop Facility and that provide such capabilities as controlling the direction of iteration, accumulating values inside the body of a loop, and evaluating expressions that precede or follow the loop body.

loop prologue

The part of the expanded loop form that contains forms that are executed before iteration begins, such as initial bindings of loop variables.

macro expansion

The process of evaluating a macro.

optional parameter

A symbol that is not required for a function to work properly; in the syntactic description, the symbol&optional precedes the optional parameter.

parallel initialization

A process whereby a set of expressions is evaluated and the results are bound to the respective variables simultaneously.


A symbol whose value is determined by the arguments that you supply when you invoke a function.

rest parameter

A construct that allows a function to have an unspecified number of arguments; it is indicated by the symbol&rest in the syntactic description.


An ordered set of elements.

sequential initialization

A process whereby one variable is assigned a value before the expression that follows it is evaluated.


The process of assigning a variable the next item in a series of items.


Standardized grammatical rules and patterns.

The Loop Facility - 9 SEP 1996

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