General accumulator

Link to the source code repository: General accumulator.

Introduction

General accumulator is a general-purpose, extensible value accumulator library. Its main interface is with-accumulator macro which sets an environment for easy accumulation. The library provides several built-in accumulators which should cover the most common use-cases but any kind of accumulators can be added because the accumulator back-end is implemented through generic functions.

(with-accumulator (NAME OBJECT &key KEYWORD-ARGUMENTS ...)
  BODY ...)

Some examples

GENACC> (with-accumulator (collect :list)
          (collect 1) (collect 2) (collect 3)
          (collect))
(1 2 3)

GENACC> (with-accumulator (collect (list 1 2 3))
          (collect 4) (collect 5)
          (collect))
(1 2 3 4 5)

GENACC> (with-accumulator (collect :vector)
          (collect "first") (collect "second")
          (collect))
#("first" "second")

GENACC> (with-accumulator (collect :string)
          (collect #\a)
          (collect "bcd")
          (collect #(#\e #\f))
          (collect '(#\g #\h #\i))
          (collect))
"abcdefghi"

GENACC> (with-accumulator (summing #'+)
          (summing 5) (summing 7) (summing 11)
          (summing))
23

GENACC> (with-accumulator (nc #'nconc)
          (nc (list 1 2 3))
          (nc (list 4 5 6))
          (nc (list 7 8 9))
          (nc))
(1 2 3 4 5 6 7 8 9)

GENACC> (with-accumulator (early-char (lambda (a b)
                                        (if (char< a b) a b)))
          (early-char #\o)
          (early-char #\b)
          (early-char #\s)
          (early-char))
#\b

For more information and examples read the project's README file.

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