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move ice-9/ and oop/ under module/

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Moved ice-9/ and oop/ under module/, with the idea being that we have
only scheme under module/. Adjusted configure.in and Makefile.am
appropriately. Put oop/ at the end of the compilation order.
This commit is contained in:
Andy Wingo 2008-11-01 12:44:21 +01:00
commit 00d0489205
95 changed files with 8 additions and 8 deletions
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module/ice-9/streams.scm Normal file
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;;;; streams.scm --- general lazy streams
;;;; -*- Scheme -*-
;;;; Copyright (C) 1999, 2001, 2004, 2006 Free Software Foundation, Inc.
;;;;
;;;; This library is free software; you can redistribute it and/or
;;;; modify it under the terms of the GNU Lesser General Public
;;;; License as published by the Free Software Foundation; either
;;;; version 2.1 of the License, or (at your option) any later version.
;;;;
;;;; This library is distributed in the hope that it will be useful,
;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;;;; Lesser General Public License for more details.
;;;;
;;;; You should have received a copy of the GNU Lesser General Public
;;;; License along with this library; if not, write to the Free Software
;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
;; the basic stream operations are inspired by
;; (i.e. ripped off) Scheme48's `stream' package,
;; modulo stream-empty? -> stream-null? renaming.
(define-module (ice-9 streams)
:export (make-stream
stream-car stream-cdr stream-null?
list->stream vector->stream port->stream
stream->list stream->reversed-list
stream->list&length stream->reversed-list&length
stream->vector
stream-fold stream-for-each stream-map))
;; Use:
;;
;; (make-stream producer initial-state)
;; - PRODUCER is a function of one argument, the current state.
;; it should return either a pair or an atom (i.e. anything that
;; is not a pair). if PRODUCER returns a pair, then the car of the pair
;; is the stream's head value, and the cdr is the state to be fed
;; to PRODUCER later. if PRODUCER returns an atom, then the stream is
;; considered depleted.
;;
;; (stream-car stream)
;; (stream-cdr stream)
;; (stream-null? stream)
;; - yes.
;;
;; (list->stream list)
;; (vector->stream vector)
;; - make a stream with the same contents as LIST/VECTOR.
;;
;; (port->stream port read)
;; - makes a stream of values which are obtained by READing from PORT.
;;
;; (stream->list stream)
;; - returns a list with the same contents as STREAM.
;;
;; (stream->reversed-list stream)
;; - as above, except the contents are in reversed order.
;;
;; (stream->list&length stream)
;; (stream->reversed-list&length stream)
;; - multiple-valued versions of the above two, the second value is the
;; length of the resulting list (so you get it for free).
;;
;; (stream->vector stream)
;; - yes.
;;
;; (stream-fold proc init stream0 ...)
;; - PROC must take (+ 1 <number-of-stream-arguments>) arguments, like this:
;; (PROC car0 ... init). *NOTE*: the INIT argument is last, not first.
;; I don't have any preference either way, but it's consistent with
;; `fold[lr]' procedures from SRFI-1. PROC is applied to successive
;; elements of the given STREAM(s) and to the value of the previous
;; invocation (INIT on the first invocation). the last result from PROC
;; is returned.
;;
;; (stream-for-each proc stream0 ...)
;; - like `for-each' we all know and love.
;;
;; (stream-map proc stream0 ...)
;; - like `map', except returns a stream of results, and not a list.
;; Code:
(define (make-stream m state)
(delay
(let ((o (m state)))
(if (pair? o)
(cons (car o)
(make-stream m (cdr o)))
'()))))
(define (stream-car stream)
"Returns the first element in STREAM. This is equivalent to `car'."
(car (force stream)))
(define (stream-cdr stream)
"Returns the first tail of STREAM. Equivalent to `(force (cdr STREAM))'."
(cdr (force stream)))
(define (stream-null? stream)
"Returns `#t' if STREAM is the end-of-stream marker; otherwise
returns `#f'. This is equivalent to `null?', but should be used
whenever testing for the end of a stream."
(null? (force stream)))
(define (list->stream l)
"Returns a newly allocated stream whose elements are the elements of
LIST. Equivalent to `(apply stream LIST)'."
(make-stream
(lambda (l) l)
l))
(define (vector->stream v)
(make-stream
(let ((len (vector-length v)))
(lambda (i)
(or (= i len)
(cons (vector-ref v i) (+ 1 i)))))
0))
(define (stream->reversed-list&length stream)
(let loop ((s stream) (acc '()) (len 0))
(if (stream-null? s)
(values acc len)
(loop (stream-cdr s) (cons (stream-car s) acc) (+ 1 len)))))
(define (stream->reversed-list stream)
(call-with-values
(lambda () (stream->reversed-list&length stream))
(lambda (l len) l)))
(define (stream->list&length stream)
(call-with-values
(lambda () (stream->reversed-list&length stream))
(lambda (l len) (values (reverse! l) len))))
(define (stream->list stream)
"Returns a newly allocated list whose elements are the elements of STREAM.
If STREAM has infinite length this procedure will not terminate."
(reverse! (stream->reversed-list stream)))
(define (stream->vector stream)
(call-with-values
(lambda () (stream->reversed-list&length stream))
(lambda (l len)
(let ((v (make-vector len)))
(let loop ((i 0) (l l))
(if (not (null? l))
(begin
(vector-set! v (- len i 1) (car l))
(loop (+ 1 i) (cdr l)))))
v))))
(define (stream-fold f init stream . rest)
(if (null? rest) ;fast path
(stream-fold-one f init stream)
(stream-fold-many f init (cons stream rest))))
(define (stream-fold-one f r stream)
(if (stream-null? stream)
r
(stream-fold-one f (f (stream-car stream) r) (stream-cdr stream))))
(define (stream-fold-many f r streams)
(if (or-map stream-null? streams)
r
(stream-fold-many f
(apply f (let recur ((cars
(map stream-car streams)))
(if (null? cars)
(list r)
(cons (car cars)
(recur (cdr cars))))))
(map stream-cdr streams))))
(define (stream-for-each f stream . rest)
(if (null? rest) ;fast path
(stream-for-each-one f stream)
(stream-for-each-many f (cons stream rest))))
(define (stream-for-each-one f stream)
(if (not (stream-null? stream))
(begin
(f (stream-car stream))
(stream-for-each-one f (stream-cdr stream)))))
(define (stream-for-each-many f streams)
(if (not (or-map stream-null? streams))
(begin
(apply f (map stream-car streams))
(stream-for-each-many f (map stream-cdr streams)))))
(define (stream-map f stream . rest)
"Returns a newly allocated stream, each element being the result of
invoking F with the corresponding elements of the STREAMs
as its arguments."
(if (null? rest) ;fast path
(make-stream (lambda (s)
(or (stream-null? s)
(cons (f (stream-car s)) (stream-cdr s))))
stream)
(make-stream (lambda (streams)
(or (or-map stream-null? streams)
(cons (apply f (map stream-car streams))
(map stream-cdr streams))))
(cons stream rest))))
(define (port->stream port read)
(make-stream (lambda (p)
(let ((o (read p)))
(or (eof-object? o)
(cons o p))))
port))
;;; streams.scm ends here