Overview: This package provides a new keyword for iterate, per, and four styles of iteration:

(iter (per x in y)) similar to doseq, binds x to each element of the result of calling seq on y.

(iter (per x on y)) similar to loop .. on, binds x to subsequent tails of the result of calling seq on y.

(iter (per x across y)) similar to loop .. across, calls indexable on y, and loops by index below count-elements binding x to subsequent values of element-at

(iter (per x of y)) similar to do-iterator, calls iterator on y, and binds x to subsequent values it produces. ensures that iterator-finish! is called. since iterator provides a default implementation for seq, indexable, and associative, any of those may also be used in a per ... of clause.

Usage: This package is intended to be used with iterate. Since Iterate tests clauses on symbol-equality, this package will have no effect unless you explicitly :use it, e.g.

  (defpackage #:foo
    (:use #:cl

Exported symbols

this package exports two symbols.


iterate driver


iterate keyword

Jason Aeschliman <>
revised BSD