add examples for pairs
svn: r16794
This commit is contained in:
Jon Rafkind
parent
b79734941f
commit
c991ada1e7
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@ -67,35 +67,78 @@ then the pair is not a list.
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@section{Pair Constructors and Selectors}
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@defproc[(pair? [v any/c]) boolean?]{Returns @scheme[#t] if @scheme[v] is
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a pair, @scheme[#f] otherwise.}
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a pair, @scheme[#f] otherwise.
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@mz-examples[
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(pair? 1)
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(pair? (cons 1 2))
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(pair? (list 1 2))
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(pair? '(1 2))
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(pair? '())
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]}
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@defproc[(null? [v any/c]) boolean?]{Returns @scheme[#t] if @scheme[v] is
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the empty list, @scheme[#f] otherwise.}
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the empty list, @scheme[#f] otherwise.
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@mz-examples[
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(null? 1)
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(null? '(1 2))
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(null? '())
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(null? (cdr (list 1)))
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]}
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@defproc[(cons [a any/c] [d any/c]) pair?]{Returns a pair whose first
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element is @scheme[a] and second element is @scheme[d].}
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element is @scheme[a] and second element is @scheme[d].
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@mz-examples[
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(cons 1 2)
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(cons 1 '())
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]}
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@defproc[(car [p pair?]) any/c]{Returns the first element of the
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pair @scheme[p].}
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pair @scheme[p].
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@mz-examples[
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(car '(1 2))
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(car (cons 2 3))
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]}
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@defproc[(cdr [p pair?]) any/c]{Returns the second element of the
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pair @scheme[p].}
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pair @scheme[p].
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@mz-examples[
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(cdr '(1 2))
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(cdr '(1))
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]}
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@defthing[null null?]{The empty list.}
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@defthing[null null?]{The empty list.
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@mz-examples[
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null
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'()
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(eq? '() null)
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]}
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@defproc[(list? [v any/c]) boolean?]{Returns @scheme[#t] if @scheme[v]
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is a list: either the empty list, or a pair whose second element is a
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list. This procedure takes amortized constant time.}
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list. This procedure takes amortized constant time.
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@mz-examples[
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(list? '(1 2))
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(list? (cons 1 (cons 2 '())))
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(list? (cons 1 2))
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]}
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@defproc[(list [v any/c] ...) list?]{Returns a newly allocated list
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containing the @scheme[v]s as its elements.}
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containing the @scheme[v]s as its elements.
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@mz-examples[
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(list 1 2 3 4)
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(list (list 1 2) (list 3 4))
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]}
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@defproc[(list* [v any/c] ... [tail any/c]) any/c]{
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Like @scheme[list], but the last argument is used as the tail of
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the result, instead of the final element. The result is a list
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only if the last argument is a list.}
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only if the last argument is a list.
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@mz-examples[
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(list* 1 2)
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(list* 1 2 (list 3 4))
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]}
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@defproc[(build-list [n exact-nonnegative-integer?]
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[proc (exact-nonnegative-integer? . -> . any)])
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@ -117,7 +160,11 @@ is the value produced by @scheme[(proc _i)].
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@defproc[(length [lst list?])
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exact-nonnegative-integer?]{
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Returns the number of elements in @scheme[lst].}
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Returns the number of elements in @scheme[lst].
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@mz-examples[
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(length (list 1 2 3 4))
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(length '())
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]}
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@defproc[(list-ref [lst any/c] [pos exact-nonnegative-integer?])
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@ -129,7 +176,12 @@ the list's first element is position @scheme[0]. If the list has
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@exnraise[exn:fail:contract].
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The @scheme[lst] argument need not actually be a list; @scheme[lst]
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must merely start with a chain of at least @scheme[pos] pairs.}
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must merely start with a chain of at least @scheme[pos] pairs.
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@mz-examples[
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(list-ref (list 'a 'b 'c) 0)
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(list-ref (list 'a 'b 'c) 1)
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(list-ref (list 'a 'b 'c) 2)
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]}
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@defproc[(list-tail [lst any/c] [pos exact-nonnegative-integer?])
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@ -140,7 +192,10 @@ Returns the list after the first @scheme[pos] elements of
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the @exnraise[exn:fail:contract].
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The @scheme[lst] argument need not actually be a list; @scheme[lst]
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must merely start with a chain of at least @scheme[pos] pairs.}
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must merely start with a chain of at least @scheme[pos] pairs.
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@mz-examples[
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(list-tail (list 1 2 3 4) 2)
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]}
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@defproc*[([(append [lst list?] ...) list?]
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@ -151,12 +206,21 @@ of the elements of the given lists in order. The last argument is used
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directly in the tail of the result.
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The last argument need not be a list, in which case the result is an
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``improper list.''}
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``improper list.''
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@mz-examples[
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(append (list 1 2) (list 3 4))
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(append (list 1 2) (list 3 4) (list 5 6) (list 7 8))
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]}
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@defproc[(reverse [lst list?]) list?]{
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Returns a list that has the same elements as @scheme[lst], but in
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reverse order.}
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reverse order.
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@mz-examples[
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(reverse (list 1 2 3 4))
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]}
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@; ----------------------------------------
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@ -169,7 +233,17 @@ Applies @scheme[proc] to the elements of the @scheme[lst]s from the
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first elements to the last. The @scheme[proc] argument must accept
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the same number of arguments as the number of supplied @scheme[lst]s,
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and all @scheme[lst]s must have the same number of elements. The
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result is a list containing each result of @scheme[proc] in order.}
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result is a list containing each result of @scheme[proc] in order.
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@mz-examples[
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(map (lambda (number)
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(+ 1 number))
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'(1 2 3 4))
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(map (lambda (number1 number2)
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(+ number1 number2))
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'(1 2 3 4)
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'(10 100 1000 10000))
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]}
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@defproc[(andmap [proc procedure?] [lst list?] ...+)
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any]{
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@ -232,7 +306,14 @@ If the @scheme[lst]s are empty, then @scheme[#f] is returned.}
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Similar to @scheme[map], but @scheme[proc] is called only for its
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effect, and its result (which can be any number of values) is
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ignored.}
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ignored.
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(mz-examples[
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(for-each (lambda (arg)
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(printf "Got ~a\n" arg)
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23)
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'(1 2 3 4))
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]}
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@defproc[(foldl [proc procedure?] [init any/c] [lst list?] ...+)
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@ -260,6 +341,11 @@ Unlike @scheme[foldr], @scheme[foldl] processes the @scheme[lst]s in
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@mz-examples[
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(foldl cons '() '(1 2 3 4))
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(foldl + 0 '(1 2 3 4))
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(foldl (lambda (a b result)
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(* result (- a b)))
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1
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'(1 2 3)
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'(4 5 6))
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]}
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@defproc[(foldr [proc procedure?] [init any/c] [lst list?] ...+)
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@ -283,7 +369,11 @@ Like @scheme[foldl], but the lists are traversed from right to left.
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Returns a list with the elements of @scheme[lst] for which
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@scheme[pred] produces a true value. The @scheme[pred] procedure is
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applied to each element from first to last.}
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applied to each element from first to last.
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@mz-examples[
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(filter positive? '(1 -2 3 4 -5))
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]}
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@defproc[(remove [v any/c] [lst list?] [proc procedure? equal?])
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@ -291,38 +381,58 @@ Returns a list with the elements of @scheme[lst] for which
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Returns a list that is like @scheme[lst], omitting the first element
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of @scheme[lst] that is equal to @scheme[v] using the comparison
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procedure @scheme[proc] (which must accept two arguments).}
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procedure @scheme[proc] (which must accept two arguments).
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@mz-examples[
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(remove 2 (list 1 2 3 2 4))
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]}
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@defproc[(remq [v any/c] [lst list?])
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list?]{
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Returns @scheme[(remove v lst eq?)].}
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Returns @scheme[(remove v lst eq?)].
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@mz-examples[
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(remq 2 (list 1 2 3 4 5))
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]}
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@defproc[(remv [v any/c] [lst list?])
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list?]{
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Returns @scheme[(remove v lst eqv?)].}
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Returns @scheme[(remove v lst eqv?)].
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@mz-examples[
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(remv 2 (list 1 2 3 4 5))
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]}
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@defproc[(remove* [v-lst list?] [lst list?] [proc procedure? equal?])
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list?]{
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Like @scheme[remove], but removes from @scheme[lst] every instance of
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every element of @scheme[v-lst].}
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every element of @scheme[v-lst].
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@mz-examples[
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(remove* 2 (list 1 2 3 2 4 5 2))
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]}
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@defproc[(remq* [v-lst list?] [lst list?])
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list?]{
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Returns @scheme[(remove* v-lst lst eq?)].}
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Returns @scheme[(remove* v-lst lst eq?)].
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@mz-examples[
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(remq* 2 (list 1 2 3 2 4 5 2))
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]}
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@defproc[(remv* [v-lst list?] [lst list?])
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list?]{
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Returns @scheme[(remove* v-lst lst eqv?)].}
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Returns @scheme[(remove* v-lst lst eqv?)].
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@mz-examples[
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(remv* 2 (list 1 2 3 2 4 5 2))
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]}
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@defproc[(sort [lst list?] [less-than? (any/c any/c . -> . any/c)]
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@ -381,19 +491,34 @@ By default, @scheme[extract-key] is applied to two list elements for
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Locates the first element of @scheme[lst] that is @scheme[equal?] to
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@scheme[v]. If such an element exists, the tail of @scheme[lst]
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starting with that element is returned. Otherwise, the result is
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@scheme[#f].}
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@scheme[#f].
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@mz-examples[
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(member 2 (list 1 2 3 4))
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(member 9 (list 1 2 3 4))
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]}
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@defproc[(memv [v any/c] [lst list?])
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(or/c list? #f)]{
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Like @scheme[member], but finds an element using @scheme[eqv?].}
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Like @scheme[member], but finds an element using @scheme[eqv?].
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@mz-examples[
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(memv 2 (list 1 2 3 4))
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(memv 9 (list 1 2 3 4))
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]}
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@defproc[(memq [v any/c] [lst list?])
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(or/c list? #f)]{
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Like @scheme[member], but finds an element using @scheme[eq?].}
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Like @scheme[member], but finds an element using @scheme[eq?].
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@mz-examples[
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(memq 2 (list 1 2 3 4))
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(memq 9 (list 1 2 3 4))
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]}
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}
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@defproc[(memf [proc procedure?] [lst list?])
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@ -401,13 +526,24 @@ Like @scheme[member], but finds an element using @scheme[eq?].}
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Like @scheme[member], but finds an element using the predicate
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@scheme[proc]; an element is found when @scheme[proc] applied to the
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element returns a true value.}
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element returns a true value.
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@mz-examples[
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(memf (lambda (arg)
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(> arg 9))
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'(7 8 9 10 11))
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]}
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@defproc[(findf [proc procedure?] [lst list?]) any/c]{
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Like @scheme[memf], but returns the element or @scheme[#f]
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instead of a tail of @scheme[lst] or @scheme[#f].}
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instead of a tail of @scheme[lst] or @scheme[#f].
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@mz-examples[
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(findf (lambda (arg)
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(> arg 9))
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'(7 8 9 10 11))
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]}
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@defproc[(assoc [v any/c] [lst (listof pair?)])
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@ -416,19 +552,29 @@ Like @scheme[memf], but returns the element or @scheme[#f]
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Locates the first element of @scheme[lst] whose @scheme[car] is
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@scheme[equal?] to @scheme[v]. If such an element exists, the pair
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(i.e., an element of @scheme[lst]) is returned. Otherwise, the result
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is @scheme[#f].}
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is @scheme[#f].
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@mz-examples[
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(assoc 3 (list (list 1 2) (list 3 4) (list 5 6)))
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(assoc 9 (list (list 1 2) (list 3 4) (list 5 6)))
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]}
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@defproc[(assv [v any/c] [lst (listof pair?)])
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(or/c pair? #f)]{
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Like @scheme[assoc], but finds an element using @scheme[eqv?].}
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Like @scheme[assoc], but finds an element using @scheme[eqv?].
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@mz-examples[
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(assv 3 (list (list 1 2) (list 3 4) (list 5 6)))
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]}
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@defproc[(assq [v any/c] [lst (listof pair?)])
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(or/c pair? #f)]{
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Like @scheme[assoc], but finds an element using @scheme[eq?].}
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Like @scheme[assoc], but finds an element using @scheme[eq?].
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@mz-examples[
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(assq 3 (list (list 1 2) (list 3 4) (list 5 6)))
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]}
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@defproc[(assf [proc procedure?] [lst list?])
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@ -436,7 +582,12 @@ Like @scheme[assoc], but finds an element using @scheme[eq?].}
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Like @scheme[assoc], but finds an element using the predicate
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@scheme[proc]; an element is found when @scheme[proc] applied to the
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@scheme[car] of an @scheme[lst] element returns a true value.}
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@scheme[car] of an @scheme[lst] element returns a true value.
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@mz-examples[
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(assf (lambda (arg)
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(> arg 2))
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(list (list 1 2) (list 3 4) (list 5 6)))
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]}
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