The document discusses how learning Haskell made the author a better Python programmer. It argues that by learning Haskell, the author was able to better understand Python code, code written by others, the Python language itself, and frameworks built for Python. Learning Haskell provided a deeper understanding of programming languages in general and allowed the author to critically evaluate their own language choices.

1. Porque aprender haskell
me fez um programador
python melhor?
@gustavopinto
gustavo@entropie.com.br

2. Porque aprender haskell
me fez um programador
python melhor?
Baseado em fatos reais
@gustavopinto
gustavo@entropie.com.br

3. Gustavo Pinto
2004 - belém, grad, php, sh
2006 - amazontic, java, xp
2008 - curitiba, msc, python
2009 - aprioriti, xp, scrum
2011 - recife, phd, haskell
2012 - entropie, lean, scala

4. Belém

5. Belém

6. Belém

7. Belém

8. Belém

9. Belém

10. DISCLAIMER

11. Não tem código

12. Não tem código
¬¬''

13. Mentira, tem mas é
pouquinho :-)

16. 1912 ~ 1954

17. 1912 ~ 1954
1936

18. 1912 ~ 1954
1936

19. ON COMPUTABLE
NUMBERS, WITH
AN APPLICATION
TO THE
ENTSCHEIDUNGS
PROBLEM

20. ON COMPUTABLE
NUMBERS, WITH
AN APPLICATION
TO THE
ENTSCHEIDUNGS
PROBLEM

21. ON COMPUTABLE
NUMBERS, WITH
AN APPLICATION
TO THE
DECISION
PROBLEM

27. 1903 ~1995

28. 1903 ~1995
1936

29. 1903 ~1995
1936

30. AN UNSOLVABLE
PROBLEM OF
ELEMENTARY
NUMBER
THEORY

33. 1936

36. 1936

37. Church-Turing thesis

38. Church-Turing thesis

39. Church-Turing thesis
Equivalentes

50. Algumas features:
● Pure functions
● Functions as first-class objects
● No side effects

51. Algumas features:
● Pure functions
● Functions as first-class objects
● No side effects
Concurrency
Friendly

54. Great.. But, what
about Python??

55. Python functional

56. Is python functional?

57. Is python functional?

58. I have never considered Python to be
heavily influenced by functional
languages, no matter what people say or
think. I was much more familiar with
imperative languages such as C and
Algol 68 and although I had made
functions first-class objects, I didn't view
Python as a functional programming
language. However, earlier on, it was
clear that users wanted to do much more
with lists and functions.
http://python-history.blogspot.com.br/2009/04/origins-of-pythons-functional-features.html

59. I have never considered Python to be
heavily influenced by functional
languages, no matter what people say or
think. I was much more familiar with
imperative languages such as C and
Algol 68 and although I had made
functions first-class objects, I didn't view
Python as a functional programming
language. However, earlier on, it was
clear that users wanted to do much more
with lists and functions.
http://python-history.blogspot.com.br/2009/04/origins-of-pythons-functional-features.html

60. I have never considered Python to be
heavily influenced by functional
languages, no matter what people say or
think. I was much more familiar with
imperative languages such as C and
Algol 68 and although I had made
functions first-class objects, I didn't view
Python as a functional programming
language. However, earlier on, it was
clear that users wanted to do much more
with lists and functions.
http://python-history.blogspot.com.br/2009/04/origins-of-pythons-functional-features.html

61. I have never considered Python to be
heavily influenced by functional
languages, no matter what people say or
think. I was much more familiar with
imperative languages such as C and
Algol 68 and although I had made
functions first-class objects, I didn't view
Python as a functional programming
language. However, earlier on, it was
clear that users wanted to do much more
with lists and functions.
http://python-history.blogspot.com.br/2009/04/origins-of-pythons-functional-features.html

62. I see list and
functions

66. if god exists:
atepassar**2
hack, hack

67. search_list = lambda l,e : [ [ idx for idx,
element in enumerate(l) if element ==
element_f ] for element_f in e]

68. search_list = lambda l,e : [ [ idx for idx,
element in enumerate(l) if element ==
element_f ] for element_f in e]

69. List comprehension
A basic comprehension for a set that contains
the first ten even natural numbers is
The part before the pipe is called the output
function, x is the variable, N is the input set and
x <= 10 is the predicate. That means that the
set contains the doubles of all natural numbers
that satisfy the predicate.
http://learnyouahaskell.com/starting-out#im-a-list-comprehension

70. List comprehension
A basic comprehension for a set that contains
the first ten even natural numbers is
The part before the pipe is called the output
function, x is the variable, N is the input set and
x <= 10 is the predicate. That means that the
set contains the doubles of all natural numbers
that satisfy the predicate.
http://learnyouahaskell.com/starting-out#im-a-list-comprehension

71. List comprehension
A basic comprehension for a set that contains
the first ten even natural numbers is
>>> [i for x in range (0, 100) if x > 10]
http://learnyouahaskell.com/starting-out#im-a-list-comprehension

72. List comprehension
A basic comprehension for a set that contains
the first ten even natural numbers is
>>> [i for x in range (0, 100) if x > 10]
>>> [[row[i] for row in matrix] for i in range(4)]
http://learnyouahaskell.com/starting-out#im-a-list-comprehension

73. List comprehension
A basic comprehension for a set that contains
the first ten even natural numbers is
>>> [i for x in range (0, 100) if x > 10]
>>> [[row[i] for row in matrix] for i in range(4)]
>>> dict([(i, chr(65+i)) for i in range(4)])
http://learnyouahaskell.com/starting-out#im-a-list-comprehension

74. List Sou foda
comprehension
A basic comprehension for a set that contains
the first ten even natural numbers is
>>> [i for x in range (0, 100) if x > 10]
>>> [[row[i] for row in matrix] for i in range(4)]
>>> dict([(i, chr(65+i)) for i in range(4)])
http://learnyouahaskell.com/starting-out#im-a-list-comprehension

75. search_list = lambda l,e : [ [ idx for idx,
element in enumerate(l) if element ==
element_f ] for element_f in e]

76. Lambda
Lambdas are basically anonymous functions
that are used because we need some functions
only once. Normally, we make a lambda with
the sole purpose of passing it to a higher-order
function.
http://learnyouahaskell.com/higher-order-functions#lambdas

77. Lambda
Lambdas are basically anonymous functions
that are used because we need some functions
only once. Normally, we make a lambda with
the sole purpose of passing it to a higher-order
function.
http://learnyouahaskell.com/higher-order-functions#lambdas

78. Lambda
>>> lambda x: x % 2
http://learnyouahaskell.com/higher-order-functions#lambdas

79. Lambda
>>> is_even = lambda x: x % 2
http://learnyouahaskell.com/higher-order-functions#lambdas

80. Lambda
>>> is_even = lambda x: x % 2
>>> is_even
<function <lambda> at 0x2a3d050>
http://learnyouahaskell.com/higher-order-functions#lambdas

81. search_list = lambda l,e : [ [ idx for idx,
element in enumerate(l) if element ==
element_f ] for element_f in e]

82. Built-in Functions
>>> for mes in enumerate (['jan', 'fev', 'mar']):
... print mes
(0, 'jan')
(1, 'fev')
(2, 'mar')

83. Built-in Functions
>>> for mes in enumerate (['jan', 'fev', 'mar']):
... print mes
(0, 'jan')
(1, 'fev')
(2, 'mar')
outras built-in functions:
● filter
● map
● reduce

84. Built-in Functions
>>> for mes in enumerate (['jan', 'fev', 'mar']):
... print mes
(0, 'jan')
(1, 'fev')
(2, 'mar')
outras built-in functions:
● filter
● map Funções de
● reduce alta ordem

85. Filter
filter(...)
filter(function or None, sequence) -> list,
tuple or string
Return those items of sequence for which
function(item) is true. [....]
>>> filter(lambda x: x % 2 == 0, range(10))

86. Filter
filter(...)
filter(function or None, sequence) -> list,
tuple or string
Return those items of sequence for which
function(item) is true. [....]
>>> is_even = lambda x: x % 2 == 0
>>> filter(is_even, range(10))

87. Map
map(...)
map(function, sequence[, sequence, ...]) -> list
Return a list of the results of applying the
function to the items of the argument sequence
(s). [....]
>>> map(lambda s: s.upper(), ['a', 'b', 'c'])

88. Reduce
reduce(...)
reduce(function, sequence[, initial]) -> value
Apply a function of two arguments
cumulatively to the items of a sequence, from
left to right, so as to reduce the sequence to a
single value. [....]
>>> reduce(lambda x,y: x * y, range(1, 4))
>>> reduce(lambda x, y: x + y, ['a', 'b', 'c', 'd'])

89. Sua High Order Function
def f(x):
return x + 1
def g(function, x):
return function(x) + function (x + 1)
print g(f, 1)

90. Sua High Order Function
def f(x):
return x + 1 not bad
def g(function, x):
return function(x) + function (x + 1)
print g(f, 1)

91. Porque aprender haskell
me fez um programador
python melhor?

92. Consegui
entender
melhor o
código do
Marcel!

93. Consegui
entender
melhor o
código
de outras
pessoas!

94. Consegui
entender
melhor
a minha
linguagem!

95. Consegui
entender
melhor
o meu
framework!

96. Resumindo

97. Domine sua
linguagem

98. Evolua com a
sua linguagem

99. Domine outras
linguagens
(Tanto quanto)

100. Entenda que
linguagens são
escolhas

101. Seja o principal
crítico das suas
escolhas

102. Para saber mais:
from functional import *

103. OBRIGADO!
@gustavopinto
gustavo@entropie.com.br