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document latest scheme/generator functions

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svn: r17613
This commit is contained in:
Jon Rafkind 2010-01-11 22:22:51 +00:00
parent 81e963bd46
commit e9165f30fe
1 changed files with 25 additions and 2 deletions
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27
collects/scribblings/reference/sequences.scrbl
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@ -194,7 +194,7 @@ as a sequence to get the key and value as separate values for each
element).} element).}
@defproc[(in-producer [producer procedure?] [stop any/c] [args any/c] ...) @defproc[(in-producer [producer procedure?] [stop any/c] [args any/c] ...)
sequence]{ sequence?]{
Returns a sequence that contains values from sequential calls to Returns a sequence that contains values from sequential calls to
@scheme[producer]. @scheme[stop] identifies the value that marks the @scheme[producer]. @scheme[stop] identifies the value that marks the
end of the sequence --- this value is not included in the sequence. end of the sequence --- this value is not included in the sequence.
@ -203,7 +203,7 @@ results with @scheme[eq?]. Note that you must use a predicate function
if the stop value is itself a function, or if the @scheme[producer] if the stop value is itself a function, or if the @scheme[producer]
returns multiple values.} returns multiple values.}
@defproc[(in-value [v any/c]) sequence]{ @defproc[(in-value [v any/c]) sequence?]{
Returns a sequence that produces a single value: @scheme[v]. This form Returns a sequence that produces a single value: @scheme[v]. This form
is mostly useful for @scheme[let]-like bindings in forms such as is mostly useful for @scheme[let]-like bindings in forms such as
@scheme[for*/list].} @scheme[for*/list].}
@ -363,6 +363,21 @@ with a stop-value known to the generator.
i) i)
]} ]}
@defform[(infinite-generator body ...)]{ Creates a function similar to
@scheme[generator] but when the last @scheme[body] is executed the function
will re-execute all the bodies in a loop.
@examples[#:eval (generator-eval)
(define welcome
(infinite-generator
(yield 'hello)
(yield 'goodbye)))
(welcome)
(welcome)
(welcome)
(welcome)
]}
@defproc[(in-generator [expr any?] ...) sequence?]{ Returns a generator @defproc[(in-generator [expr any?] ...) sequence?]{ Returns a generator
that can be used as a sequence. The @scheme[in-generator] procedure takes care of the that can be used as a sequence. The @scheme[in-generator] procedure takes care of the
case when @scheme[expr] stops producing values, so when the @scheme[expr] case when @scheme[expr] stops producing values, so when the @scheme[expr]
@ -380,3 +395,11 @@ completes, the generator will end.
@defform[(yield expr)]{ Saves the point of execution inside a generator @defform[(yield expr)]{ Saves the point of execution inside a generator
and returns a value.} and returns a value.}
@defproc[(sequence->generator [s sequence?]) (-> any?)]{ Returns a generator
that returns elements from the sequence, @scheme[s], each time the generator
is invoked.}
@defproc[(sequence->repeated-generator [s sequence?]) (-> any?)]{ Returns a generator
that returns elements from the sequence, @scheme[s], similar to
@scheme[sequence->generator] but looping over the values in the sequence
when no more values are left.}