NAME
Data::Monad::CondVar - The CondVar monad.
SYNOPSIS
use Data::Monad::CondVar;
# The sleep sort
my @list = (3, 5, 2, 4, 9, 1, 8);
my @result;
AnyEvent::CondVar->all(
map {
cv_unit($_)->sleep($_ / 1000)
->map(sub { push @result, @_ });
} @list
)->recv;
DESCRIPTION
Data::Monad::CondVar adds monadic operations to AnyEvent::CondVar.
Since this module extends AnyEvent::CondVar directly, you can call monadic methods anywhere there are CondVars.
This module is marked EXPERIMENTAL. API could be changed without any notice.
METHODS
-
$cv = as_cv($cb->($cv))
A helper for rewriting functions using callbacks to ones returning CVs.
my $cv = as_cv { http_get "http://google.ne.jp", $_[0] }; my ($data, $headers) = $cv->recv;
-
$cv = cv_unit(@vs)
-
$cv = cv_zero()
-
$cv = cv_fail($v)
-
$f = cv_flat_map_multi(\&f, $cv1, $cv2, ...)
-
$f = cv_map_multi(\&f, $cv1, $cv2, ...)
-
$cv = cv_sequence($cv1, $cv2, ...)
These are shorthand of methods which has the same name.
-
$cv = call_cc($f->($cont))
Calls
$f
with current continuation,$cont
.$f
must return a CondVar object. If you call$cont
in$f
, results are sent to$cv
directly and codes left in$f
will be skipped.You can use
call_cc
to escape a deeply nested call structure.sub myname { my $uc = shift; return call_cc { my $cont = shift; cv_unit("hiratara")->flat_map(sub { return $cont->(@_) unless $uc; # escape from an inner block cv_unit @_; })->map(sub { uc $_[0] }); }; } print myname(0)->recv, "\n"; # hiratara print myname(1)->recv, "\n"; # HIRATARA
-
unit
-
flat_map
Overrides methods of Data::Monad::Base::Monad.
-
zero
Overrides methods of Data::Monad::Base::MonadZero. It uses
fail
method internally. -
$cv = AnyEvent::CondVar->fail($msg)
Creates the new CondVar object which represents a failed operation. You can use
catch
to handle failed operations. -
$cv = AnyEvent::CondVar->any($cv1, $cv2, ...)
Takes the earliest value from
$cv1
,$cv2
, ... -
$cv = AnyEvent::CondVar->all($cv1, $cv2, ...)
Takes all values from
$cv1
,$cv2
, ...This method works completely like
<Data::Monad::Base::Monad-
sequence>>, but you may want use this method for better cancellation. -
$cv->cancel
Cancels computations for this CV. This method just calls the call back which is set in the
canceler
field.<$cv-
recv>> may never return from blocking after you callcancel
. -
$cv->canceler($cb->())
-
$code = $cv->canceler
The accessor of the method to cancel. You should set this field appropriately when you create the new CondVar object.
my $cv = AE::cv; my $t = AE::timer $sec, 0, sub { $cv->send(@any_results); $cv->canceler(undef); # Destroy cyclic refs }; $cv->canceler(sub { undef $t });
-
$cv = $cv1->or($cv2)
If
$cv1
croaks,or
returns the CondVar object which contains values of$cv2
. Otherwise it returns$cv1
's values.or
would bemplus
on Haskell. -
$cv = $cv1->catch(
$cb->($ @))If
$cv1
croaks,$cb
is called and it returns the new CondVar object containing its result. Otherwisecatch
does nothing.$cb
must return a CondVar object.You can use this method to handle errors.
cv_unit(1, 0) ->map(sub { $_[0] / $_[1] }) ->catch(sub { my $exception = shift; $exception =~ /Illegal division/ ? cv_unit(0) # recover from errors : cv_fail($exception); # rethrow });
-
$cv = $cv1->sleep($sec)
Sleeps
$sec
seconds, and just sends values of$cv1
to$cv
. -
$cv = $cv1->timeout($sec)
If
$cv1
doesn't compute any values within$sec
seconds,$cv
will be receivedundef
and$cv1
will be canceled.Otherwise
$cv
will be received$cv1
's results. -
$cv = $cv1->retry($max, [$pace, ], $f->(@v))
Continue to call
flat_map($f)
until$f
returns a normal value which doesn't croak.$max
is maximum number of retries,$pace
is how long it sleeps between each retry. The default value of$pace
is0
.
AUTHOR
hiratara <hiratara {at} cpan.org>
SEE ALSO
LICENSE
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.