1 ! Copyright (C) 2006 Chris Double.
2 ! See http://factorcode.org/license.txt for BSD license.
4 USING: help.markup help.syntax sequences strings lists ;
8 { $values { "car" "a quotation with stack effect ( -- X )" } { "cdr" "a quotation with stack effect ( -- cons )" } { "promise" "the resulting cons object" } }
9 { $description "Constructs a cons object for a lazy list from two quotations. The " { $snippet "car" } " quotation should return the head of the list, and the " { $snippet "cons" } " quotation the tail when called. When " { $link cons } " or " { $link cdr } " are called on the lazy-cons object then the appropriate quotation is called." }
10 { $see-also cons car cdr nil nil? } ;
12 { 1lazy-list 2lazy-list 3lazy-list } related-words
15 { $values { "a" "a quotation with stack effect ( -- X )" } { "lazy-cons" "a lazy-cons object" } }
16 { $description "Create a lazy list with 1 element. The element is the result of calling the quotation. The quotation is only called when the list element is requested." } ;
19 { $values { "a" "a quotation with stack effect ( -- X )" } { "b" "a quotation with stack effect ( -- X )" } { "lazy-cons" "a lazy-cons object" } }
20 { $description "Create a lazy list with 2 elements. The elements are the result of calling the quotations. The quotations are only called when the list elements are requested." } ;
23 { $values { "a" "a quotation with stack effect ( -- X )" } { "b" "a quotation with stack effect ( -- X )" } { "c" "a quotation with stack effect ( -- X )" } { "lazy-cons" "a lazy-cons object" } }
24 { $description "Create a lazy list with 3 elements. The elements are the result of calling the quotations. The quotations are only called when the list elements are requested." } ;
27 { $values { "cons" "a cons object" } { "memoized-cons" "the resulting memoized-cons object" } }
28 { $description "Constructs a cons object that wraps an existing cons object. Requests for the car, cdr and nil? will be remembered after the first call, and the previous result returned on subsequent calls." }
29 { $see-also cons car cdr nil nil? } ;
32 { $values { "n" "an integer index" } { "list" "a cons object" } { "elt" "the element at the nth index" } }
33 { $description "Outputs the nth element of the list." }
34 { $see-also llength cons car cdr } ;
37 { $values { "list" "a cons object" } { "n" "a non-negative integer" } }
38 { $description "Outputs the length of the list. This should not be called on an infinite list." }
39 { $see-also lnth cons car cdr } ;
42 { $values { "cons" "a cons object" } { "car" "the head of the list" } { "cdr" "the tail of the list" } }
43 { $description "Put the head and tail of the list on the stack." } ;
45 { leach lreduce lmap lmap-with ltake lfilter lappend lfrom lfrom-by lconcat lcartesian-product lcartesian-product* lcomp lcomp* lmerge lreduce lwhile luntil } related-words
48 { $values { "list" "a cons object" } { "quot" "a quotation with stack effect ( obj -- )" } }
49 { $description "Call the quotation for each item in the list." } ;
52 { $values { "list" "a cons object" } { "identity" "an object" } { "quot" "a quotation with stack effect ( prev elt -- next )" } { "result" "the final result" } }
53 { $description "Combines successive elements of the list using a binary operation, and outputs the final result." } ;
56 { $values { "list" "a cons object" } { "quot" "a quotation with stack effect ( obj -- X )" } { "result" "resulting cons object" } }
57 { $description "Perform a similar functionality to that of the " { $link map } " word, but in a lazy manner. No evaluation of the list elements occurs initially but a " { $link <lazy-map> } " object is returned which conforms to the list protocol. Calling " { $link car } ", " { $link cdr } " or " { $link nil? } " on this will evaluate elements as required." } ;
60 { $values { "value" "an object" } { "list" "a cons object" } { "quot" "a quotation with stack effect ( obj elt -- X )" } { "result" "resulting cons object" } }
61 { $description "Variant of " { $link lmap } " which pushes a retained object on each invocation of the quotation." } ;
64 { $values { "n" "a non negative integer" } { "list" "a cons object" } { "result" "resulting cons object" } }
65 { $description "Outputs a lazy list containing the first n items in the list. This is done a lazy manner. No evaluation of the list elements occurs initially but a " { $link <lazy-take> } " object is returned which conforms to the list protocol. Calling " { $link car } ", " { $link cdr } " or " { $link nil? } " on this will evaluate elements as required." } ;
68 { $values { "list" "a cons object" } { "quot" "a quotation with stack effect ( -- X )" } { "result" "resulting cons object" } }
69 { $description "Perform a similar functionality to that of the " { $link filter } " word, but in a lazy manner. No evaluation of the list elements occurs initially but a " { $link <lazy-filter> } " object is returned which conforms to the list protocol. Calling " { $link car } ", " { $link cdr } " or " { $link nil? } " on this will evaluate elements as required." } ;
72 { $values { "list" "a cons object" } { "quot" "a quotation with stack effect ( X -- bool )" } { "result" "resulting cons object" } }
73 { $description "Outputs a lazy list containing the first items in the list as long as " { $snippet "quot" } " evaluates to t. No evaluation of the list elements occurs initially but a " { $link <lazy-while> } " object is returned with conforms to the list protocol. Calling " { $link car } ", " { $link cdr } " or " { $link nil? } " on this will evaluate elements as required." } ;
76 { $values { "list" "a cons object" } { "quot" "a quotation with stack effect ( X -- bool )" } { "result" "resulting cons object" } }
77 { $description "Outputs a lazy list containing the first items in the list until after " { $snippet "quot" } " evaluates to t. No evaluation of the list elements occurs initially but a " { $link <lazy-while> } " object is returned with conforms to the list protocol. Calling " { $link car } ", " { $link cdr } " or " { $link nil? } " on this will evaluate elements as required." } ;
80 { $values { "list" "a cons object" } { "vector" "the list converted to a vector" } }
81 { $description "Convert a list to a vector. If the list is a lazy infinite list then this will enter an infinite loop." }
82 { $see-also list>array } ;
85 { $values { "list" "a cons object" } { "array" "the list converted to an array" } }
86 { $description "Convert a list to an array. If the list is a lazy infinite list then this will enter an infinite loop." }
87 { $see-also list>vector } ;
90 { $values { "list1" "a cons object" } { "list2" "a cons object" } { "result" "a lazy list of list2 appended to list1" } }
91 { $description "Perform a similar functionality to that of the " { $link append } " word, but in a lazy manner. No evaluation of the list elements occurs initially but a " { $link <lazy-append> } " object is returned which conforms to the list protocol. Calling " { $link car } ", " { $link cdr } " or " { $link nil? } " on this will evaluate elements as required. Successive calls to " { $link cdr } " will iterate through list1, followed by list2." } ;
94 { $values { "n" "an integer" } { "quot" "a quotation with stack effect ( -- int )" } { "list" "a lazy list of integers" } }
95 { $description "Return an infinite lazy list of values starting from n, with each successive value being the result of applying quot to n." } ;
98 { $values { "n" "an integer" } { "list" "a lazy list of integers" } }
99 { $description "Return an infinite lazy list of incrementing integers starting from n." } ;
102 { $values { "index" "an integer 0 or greater" } { "seq" "a sequence" } { "list" "a list" } }
103 { $description "Convert the sequence into a list, starting from the 'index' offset into the sequence." }
104 { $see-also >list } ;
107 { $values { "object" "an object" } { "list" "a list" } }
108 { $description "Convert the object into a list. Existing lists are passed through intact, sequences are converted using " { $link seq>list } " and other objects cause an error to be thrown." }
109 { $see-also seq>list } ;
111 { leach lreduce lmap lmap-with ltake lfilter lappend lfrom lfrom-by lconcat lcartesian-product lcartesian-product* lcomp lcomp* lmerge lreduce lwhile luntil } related-words
114 { $values { "list" "a list of lists" } { "result" "a list" } }
115 { $description "Concatenates a list of lists together into one list." } ;
117 HELP: lcartesian-product
118 { $values { "list1" "a list" } { "list2" "a list" } { "result" "list of cartesian products" } }
119 { $description "Given two lists, return a list containing the cartesian product of those lists." } ;
121 HELP: lcartesian-product*
122 { $values { "lists" "a list of lists" } { "result" "list of cartesian products" } }
123 { $description "Given a list of lists, return a list containing the cartesian product of those lists." } ;
126 { $values { "list" "a list of lists" } { "quot" "a quotation with stack effect ( seq -- X )" } { "result" "the resulting list" } }
127 { $description "Get the cartesian product of the lists in " { $snippet "list" } " and call " { $snippet "quot" } " call with each element from the cartesian product on the stack, the result of which is returned in the final " { $snippet "list" } "." } ;
130 { $values { "list" "a list of lists" } { "guards" "a sequence of quotations with stack effect ( seq -- bool )" } { "quot" "a quotation with stack effect ( seq -- X )" } { "list" "the resulting list" } { "result" "a list" } }
131 { $description "Get the cartesian product of the lists in " { $snippet "list" } ", filter it by applying each guard quotation to it and call " { $snippet "quot" } " call with each element from the remaining cartesian product items on the stack, the result of which is returned in the final " { $snippet "list" } "." }
133 { $code "{ 1 2 3 } >list { 4 5 6 } >list 2list { [ first odd? ] } [ first2 + ] lcomp*" }
137 { $values { "list1" "a list" } { "list2" "a list" } { "result" "lazy list merging list1 and list2" } }
138 { $description "Return the result of merging the two lists in a lazy manner." }
140 { $example "USING: lazy-lists prettyprint ;" "{ 1 2 3 } >list { 4 5 6 } >list lmerge list>array ." "{ 1 4 2 5 3 6 }" }
144 { $values { "stream" "a stream" } { "result" string } }
145 { $description "Returns a lazy list of all characters in the file. " { $link car } " returns the next character in the file, " { $link cdr } " returns the remaining characters as a lazy list. " { $link nil? } " indicates end of file." }
146 { $see-also llines } ;
149 { $values { "stream" "a stream" } { "result" "a list" } }
150 { $description "Returns a lazy list of all lines in the file. " { $link car } " returns the next lines in the file, " { $link cdr } " returns the remaining lines as a lazy list. " { $link nil? } " indicates end of file." }
151 { $see-also lcontents } ;