=item B<< match_on_type $value => ( $type => \&action, ... ?\&default ) >>
-This is a utility function for doing simple type based dispatching
-similar to match/case in O'Caml and case/of in Haskell. It does not
-claim to be as featureful as either of those and does not support any
-kind of automatic destructuring bind. However it is suitable for a fair
-amount of your dispatching needs, for instance, here is a simple
-Perl pretty printer dispatching over the core Moose types.
+This is a utility function for doing simple type based dispatching similar to
+match/case in O'Caml and case/of in Haskell. It is not as featureful as those
+languages, nor does not it support any kind of automatic destructuring
+bind. Here is a simple Perl pretty printer dispatching over the core Moose
+types.
sub ppprint {
my $x = shift;
- match_on_type $x =>
- HashRef => sub {
+ match_on_type $x => (
+ HashRef => sub {
my $hash = shift;
- '{ ' . (join ", " => map {
- $_ . ' => ' . ppprint( $hash->{ $_ } )
- } sort keys %$hash ) . ' }' },
- ArrayRef => sub {
+ '{ '
+ . (
+ join ", " => map { $_ . ' => ' . ppprint( $hash->{$_} ) }
+ sort keys %$hash
+ ) . ' }';
+ },
+ ArrayRef => sub {
my $array = shift;
- '[ '.(join ", " => map { ppprint( $_ ) } @$array ).' ]' },
- CodeRef => sub { 'sub { ... }' },
- RegexpRef => sub { 'qr/' . $_ . '/' },
- GlobRef => sub { '*' . B::svref_2object($_)->NAME },
+ '[ ' . ( join ", " => map { ppprint($_) } @$array ) . ' ]';
+ },
+ CodeRef => sub {'sub { ... }'},
+ RegexpRef => sub { 'qr/' . $_ . '/' },
+ GlobRef => sub { '*' . B::svref_2object($_)->NAME },
Object => sub { $_->can('to_string') ? $_->to_string : $_ },
- ScalarRef => sub { '\\' . ppprint( ${$_} ) },
- Num => sub { $_ },
- Str => sub { '"'. $_ . '"' },
- Undef => sub { 'undef' },
- => sub { die "I don't know what $_ is" };
+ ScalarRef => sub { '\\' . ppprint( ${$_} ) },
+ Num => sub {$_},
+ Str => sub { '"' . $_ . '"' },
+ Undef => sub {'undef'},
+ => sub { die "I don't know what $_ is" }
+ );
}
Or a simple JSON serializer:
sub to_json {
my $x = shift;
- match_on_type $x =>
- HashRef => sub {
+ match_on_type $x => (
+ HashRef => sub {
my $hash = shift;
- '{ ' . (join ", " => map {
- '"' . $_ . '" : ' . to_json( $hash->{ $_ } )
- } sort keys %$hash ) . ' }' },
- ArrayRef => sub {
+ '{ '
+ . (
+ join ", " =>
+ map { '"' . $_ . '" : ' . to_json( $hash->{$_} ) }
+ sort keys %$hash
+ ) . ' }';
+ },
+ ArrayRef => sub {
my $array = shift;
- '[ ' . (join ", " => map { to_json( $_ ) } @$array ) . ' ]' },
- Num => sub { $_ },
- Str => sub { '"'. $_ . '"' },
- Undef => sub { 'null' },
- => sub { die "$_ is not acceptable json type" };
+ '[ ' . ( join ", " => map { to_json($_) } @$array ) . ' ]';
+ },
+ Num => sub {$_},
+ Str => sub { '"' . $_ . '"' },
+ Undef => sub {'null'},
+ => sub { die "$_ is not acceptable json type" }
+ );
}
-Based on a mapping of C<$type> to C<\&action>, where C<$type> can be
-either a string type or a L<Moose::Meta::TypeConstraint> object, and
-C<\&action> is a CODE ref, this function will dispatch on the first
-match for C<$value>. It is possible to have a catch-all at the end
-in the form of a C<\&default> CODE ref.
+The matcher is done by mapping a C<$type> to an C<\&action>. The C<$type> can
+be either a string type or a L<Moose::Meta::TypeConstraint> object, and
+C<\&action> is a subroutine reference. This function will dispatch on the
+first match for C<$value>. It is possible to have a catch-all by providing an
+additional subroutine reference as the final argument to C<match_on_type>.
=back