Unpolished talk on functional concepts in perl.
2. What Am I 3. Whats this talk all about? 4. History 5. How 6.
Why not? 7. But I dont use/appreciate/like perl? 8. Functional
Programming is Easy 9. So easy sysadmins do it 10. In the
beginning... 11. Wrote Pearl Perl 12. People wanted a sort
functionLarry was generous 13. sortF(a, a), [a] --------> [a]
14. @sorted_list= sort {$_[0] $_[1]} @list 15. @sorted_list= sort
{$a $b } @list 16. @sorted_list = sort {$a $b} @list 17. sort
String sortingsort {$a cmp $b} Also string sortingsort {$a $b} Sort
numericallysort &comparator Sort by function named comparator
18. sort {@a = split ///, $a;@b = split ///, $b;($a[2] $b[2])||
($a[1] $b[1])|| ($a[0] $b[0])|| 0;} @list_of_dmy_dates 19. 1988 -
Perl 2.01989 - Perl 3.01991 - Perl 4.0 20. grepF(a, a), [a]
--------> [a] 21. mapF(a), [a] --------> [a] 22. 1994 Perl
5.0 23. memoizeF(a) b --------------> F(a) b 24.
List::UtilreduceF(a, b) b, [a] --------------> b 25.
List::MoreUtilsany, all, none, notall, true, false,
firstidx,first_index, lastidx, part, mesh,last_index, insert_after,
zip, uniq, apply, indexes, after, after_incl, before, before_incl,
firstval, first_value, lastval,last_value, pairwise, distinct,
minmax 26. So Perl evolved a functional theme 27. So how do I make
functional stuff inperl instead of just using it? 28. Lexical
scoping 29. First class functions 30. Thats about it.Your language
does that too right? 31. So lets write a function that rolls a die
32. my $dx = sub {my ($sides) = @_;return (rand() * $sides) + 1;}my
$roll = $dx->(6); 33. I dont like rolling 1s though so... 34. my
$cheat = sub {my ($roll) = @_;if ($roll < 2) {return 2;} else
{return $roll;}} 35. I dont want to get caught turning the die over
though so ... 36. my $inconspicuous_dx = sub {my ($sides) =
@_;return $cheat->($dx->($sides));} 37. my $compose = sub {my
($fa, $fb) = @_;return sub { return $fa->($fb->(@_));}} 38.
my $inconspicuous_dx =$compose->($cheat, $dx);my $better_roll
=$inconspicuous_dx->(6); 39. Monads in PerlMasahiro Honma
(hiratara) YAPC::Asia 2011Slides are in english Data::Monad 40. All
I ever need is d6! 41. my $d6 = sub { return
$inconspicuous_dx->(6);};my $roll_a_6 = $d6->(); 42. Too lazy
to roll 20d6 43. my $dice_tower_maker = sub {my ($die) = @_;return
sub { my ($rolls) = @_; return map {$die->() } (1 .. $rolls);}}
44. my $dice_tower =$dice_tower_generator->($d6);say join(, ,
$dice_tower->(20)); 45. use List::Util;say sum
$dice_tower->(20); 46. use List::Util;say reduce {$a +
$b}$dice_tower->(20); 47. So why not use this stuff for
everything? 48. The compilers not out to help you 49. Declaring
functions gets obtuseafter awhile 50. Purity isnt an option,
everythingchanges 51. The community loves objects 52. If it was
simple in a functionallanguage it probably takes some hacking to
make it work in perl 53. And the language isnt extensible,yet 54.
Good things are to come 55. Perl 6 56. Static typingBetter
syntaxBlocks and closuresList comprehensionAutomatic
parallelisationLots more 57. ThanksQuestions?
