functional Perl 6

important functional features Haskell has, that are supported by Perl 6 too and the cultural differences between Perl and functional

Transcript

1. Perl 6 functional
2. Previously: general Array / Hash Regex OOP operator
3. func. programming What is it? What is it good for? How much can P6? How it's done in P6?
4. Features: parameter, functions, HOP (abstract) types, -classes, -inferenz lists-, comprehension, generators, tuple, currying,folding,map,filter pattern matching (MMD)
5. Funky Features: We have almost all!
6. Funky Features: We have almost all!
7. Perl Philosophy moe than 1 Way: programming for adults
8. What is it? funky programming
9. What is it? no coupling of data and code with objects
10. What is it? only functions returng results
11. What is it? very high level of abstraction
12. What is it? programmable programming lang
13. Functional: programming for mathematicians
14. Functional: old school (58): LIS P , S c h e m e , λc alc ulus new school (70's): ML, Ocaml, Haskell
15. Started by:
16. Started by:
17. later:
18. Functional: old school: ty p e le ss new school: typed
19. Functional: old school: Perl 5 new school: Perl 6
21. function >> sub sub sent { my $var = ... return $r; }
22. once “functional” if ($val eq '...'){ … }
23. recursion sub r { r($val) if … }
24. sub call { ... @_; } call ( @data ); variadic function
25. anonymous & first class return sub { … } return $coderef;
26. first class functional call( $coderef, @data);
27. high class functional sort $coderef @data;
28. High Order Func. sort map grep
29. only missing: macros
30. macro missing: Rolf Langsdorf is working on that
31. macro missing: github.com/LanX/Macro act.yapc.eu/lpw2014/talk/5804 yt/watch?v=i-Xz_9nFlvI
33. What is it? math is me mimo ... no side effects … mu ba ke
34. my => no side effects sub sent { my $var = ... return $r; }
35. procedural sub sent { if ($flag == …) { …} }
36. functional if ($flag == …) { eval “sub sent{...}”; }
37. What is it? programmable programming lang
38. What is it? very high level of abstraction
39. What is it? unified structure
40. functional world
41. Perl Philosophy more than 1 Way: programming for adults
42. Perl 5 Philosophy more than 1 Way: programming for assholekids
43. Perl 5 vs structure known mechanisms: signatures, types, objects
44. Perl 5.20: sub sent($s, $p, $o){ my $var = ... return $r; }
45. Perl 6: sub pwr(Int $b, Int $e {$^e < 22 }) { return $b ** $e; }
46. Perl 6: sub add(::T $a, T $b){ return $a + $b; }
47. Multi Method Dispatch multi sub ask (Num $p){ multi sub ask (Str $p){ ask (“what now?”);
48. Multi Method Dispatch $var ~~ … ;
49. Pattern Matching multi sub ask (Num $p){ multi sub ask (Str $p){ ask (“what now?”);
50. --< structure >++ constraint P5 <- P6 -> Has kell
51. Perl Philosophy more than 1 Way: programming for all
52. Perl: no prohibition
53. Perl: no prohibition
54. Perl: no prohibition
55. Perl: no prohibition changeable variables
56. Perl: no prohibition changeable variables sequential statements
57. Perl: no prohibition changeable variables sequential statements tweaking internals (OOP)
58. Perl: no prohibition changeable variables sequential statements tweaking internals (OOP) dirty macros (C, source filter)
59. Perl Philosophy make the hard possible: access to everything
60. Perl Philosophy keep the everyday simple: cut unnecessary syntax
61. keep it simple $text = slurp 'poem.txt';
62. keep it simple @vers = lines 'poem.txt'.IO;
63. keep it simple for @vers { ...
64. lazy eval for 'poem.txt'.IO.lines {
65. Iterators for (@a,$b,”i”) {…} say for <*>; File::find({...});
66. Iterators for @a,$b,”i” {…} say $_.path for ".".IO.dir
67. Iterators for 1..10 {…} for 100,81...4 {…}
68. Iterators for reverse 1..10 {…} for 100,81...4 {…} # 100 81 62 43 24 5
69. Iterators for reverse 1..10 {…} for 100,81,64...4 {…} # .. 49 36 25 16 9 4 ??
70. Iterators for reverse 1..10 {…} for 100,81,64...4 {…} # Error
71. Iterators for 100, {(sqrt($^n)–1)**2} … 4 { # 100 81 64 49 36 25 16 9 4
72. Iterators grep{$_>= 4}, map {$_**2}, reverse 0..10; # 100 81 64 49 36 25 16 9 4
73. Iterators grep{$_>= 4} <== map {$_**2} <== reverse 0..10; # 100 81 64 49 36 25 16 9 4
74. Iterators reverse 0..10 ==> map {$_**2} ==> grep{$_>= 4}; # 100 81 64 49 36 25 16 9 4
75. Iterators @r = gather {.. take ..}
76. Iterators .. … gather / take
77. Iterators no loop
78. Iterators no loop no changing var
79. Iterators no loop no changing var recursion
80. anonymous function @r = gather { ..take.. }
81. for @li Z @re -> $l,$r { parallel processing
82. for @l Z @m Z @r -> $l, $m, $r { ... parallel processing
83. for zip(@l;@m;@r) -> $l, $m, $r { ... parallel processing
84. Types perl6 -e 'say (2,3).WHAT' (Parcel) '@(2,3).WHAT' (List )
85. Types perl6 -e 'say "d".WHAT' (Str) 'my @a;say @a.WHAT' (Array)
86. Types in P6 elaborat tpe hierarchy for expressive signatures
87. Numbers whole number rational number complex number
88. Numbers '((1/3) + (1/6)).nude' 1 2 'say sqrt( -1+0i)' 6.12323399573677e-17+1i
89. Function in P5 Coderef with opaque CV-Structure
90. Function in P6 m e t a o b j e c t k n o w s : n r . & ( s u b - ) t y p e s o f p a r a m e t e r a n d r e t u r n v a l u e s
91. Metaops & Ops functions with visual names
92. Metaops [ ] [\ ] << >> R X Z =
93. Metaops [ ] [\ ] << >> X Z
94. Metaopmethods reduce() triangle() zipwith() crosswith()
95. my $min = $a min $b; Numeric Op
96. my $min = min @rray; New:
97. my $min = [min] @rray; previously:
98. my Bool $sorted = [ < ] @rray; sorted?
99. my $sum = [ + ] @rray; sum
100. my $sum =( @rray[0] + (@rray[1] + @rray[2] )); with 3 elements
101. my $sum =(( @rray[0] + @rray[1])+@rray[2]); with 3 elements
102. #associativity left my $sum = [ + ] @rray; # (((..+..) + ..) + ..) foldl / foldr
103. f o l d l : : ( a - > b - > a ) - > a - > [ b ] - > a f o l d l f z [ ] = z f o l d l f z ( x : x s ) = f o l d l f ( f z x ) x s foldl
104. sub add (Int $a, Int $b --> Int) {$a + $b}; sub foldl( &f:(Int, Int --> Int ), Int $sum, List:Int $l --> Int) { if $l.elems > 0 { my Int $first = shift $l; foldl(&f, &f($sum, $first), $l)} else {$sum} }; say foldl(&add, 0, [1..4]); foldl in P6
105. not there out of box easy to implement because nested signtures foldl in P6
106. #associativity left my $sum = [ + ] @rray; # (((..+..) + ..) + ..) foldl / foldr
107. #uses associativity of Op my $sum = [ + ] @rray; foldl / foldr
108. @rray.reduce(&[+]); boundary val
109. <1 2> X~ <a b> '1a','1b','2a','2b' cartesian pairs
110. <1 2> Z~ <a b> '1a','1b','2a','2b' zip pairs
111. (<1 2>;<3 4>).zipwith(&[*]) <1 2> Z* <3 4> metaop Z
112. Hyper !!!
113. @age >>++; Birthday !!!
114. Birthday !!! @age >>+=>> 1;
115. @age == 18, 22, 35; @age = @age >>+>> 1; @age == 19, 23, 36; all age
116. @age == 18, 22, 35; @age = @age <<+<< 1; @age == 19; one ages
117. <18, 22, 35> >>+<< <1, 2> <18, 22, 35> <<+>> <1, 2> interesting cases
118. <18, 22, 35> >>+<< <1, 2> ERROR <18, 22, 35> <<+>> <1, 2> 19, 24, 36 interesting cases
119. async primitives promise / future channel, supply
120. Memoization sub expensive is cached { … }
121. Cheat Functional sub expensive is pure { … }
122. Currying applying one operand at a time
123. Currying f : X x Y --> Z ==> f : X --> ( Y --> Z )
124. Currying my &func := &substr.assuming('YAPC'); say func(0, 2); YA
125. hygienic Macro macro CompileTime(){ quasi { DateTime.now() }; }
126. hygienic is default macro is parsed Compile Time () { quasi { DateTime.now() }; }
127. dirty is possible macro is reparsed Comp T( { quasi { DateTime.now() }; }
128. Thank You