elixir KERNEL 3

Question 1

to_charlist(:hello)

Answer 1

=> ‘hello’

Question 2

x = %{“data” => %{user: %{id: 1}}}

pop_in(x[“data”][:user][:id])

Answer 2

=> {1, %{“data” => %{user: %{}}}}

Question 3

trunc(-1.45)

Answer 3

=> -1

Question 4

~w(cat #{“ dog bird “})

Answer 4

=> [“cat”, “dog”, “bird”]

Question 5

body = %{“data” => %{id: 1}}

x = pop_in(body[“data”][:id])

y = pop_in(body, [“data”, :id])

x == y

Answer 5

=> true

Question 6

~w(cat #{:dog} bird)

Answer 6

=> [“cat”, “dog”, “bird”]

Question 7

tl([1, 2, 3])

Answer 7

=> [2, 3]

Question 8

send self(), “hello”

Answer 8

=> “hello”

Question 9

bit_size(<<1, 2, 3>>)

Answer 9

=> 24

Question 10

unless 1 + 2 == 3, do: “hey”

Answer 10

=> nil

Question 11

binary_part(“flashcards”, 0, 5)

Answer 11

=> “flash”

Question 12

binary_part(“hello you”, 9, -3)

Answer 12

=> “you”

Question 13

unless 1 + 2 == 3 do

“hello”

else

“good bye”

end

Answer 13

=> “good bye”

Question 14

unless 1 + 2 == 5, do: “hey”

Answer 14

=> “hey”

Question 15

match?(“h”, “h”)

Answer 15

=> true

Question 16

match?({:a, 1}, {:a, 1})

Answer 16

=> true

Question 17

bit_size(<<1::2, 2::3>>)

Answer 17

=> 5

Question 18

Atom.to_string :hello |> String.upcase

Answer 18

** (FunctionClauseError)

no function clause matching in String.upcase/2

*Note: |> has higher precedence.
Therefore :hello is applied to String.upcase first.

Question 19

x = %{“data” => %{user: %{id: 1}}}

pop_in(x, [“data”, :user, :id])

Answer 19

=> {1, %{“data” => %{user: %{}}}

Question 20

x = %{“y” => %{user: %{id: 1}}}

put_in(x[“y”][:user][:id], 2)

Answer 20

=> %{“y” => %{user: %{id: 2}}}

Question 21

try do

raise “hello”

rescue

e in [RuntimeError] -> “caught you!”

end

Answer 21

=> “caught you!”

Question 22

tuple_size({1, “h”, :a})

Answer 22

=> 3

Question 23

var = “bon”

Regex.match?(~r/bbon/, “rib#{var}”)

Answer 23

=> true

Question 24

port = Port.open(

{:spawn, “cat”},

[:binary]

)

is_port(port)

Answer 24

=> true

Question 25

~S(b#{o}n)

Answer 25

=> “b#{o}n”

*Note: Returns a string without escaping characters
and without interpolations.

Question 26

raise(ArgumentError, message: “Error details”)

Answer 26

** (ArgumentError)
Error details

Question 27

nil || 2

Answer 27

=> 2

*Note: Returns the second expression only if the first one is false or nil

Question 28

d = “dog”

~w(cat #{d} bird)

Answer 28

=> [“cat”, “dog”, “bird”]

*Note: Returns a list of “words” split by whitespace. Character unescaping and interpolation happens for each word.

Question 29

x = 1

match?(^x, 1)

Answer 29

=> true

Question 30

~N[2015-01-13T13:00:07.001]

Answer 30

=> ~N[2015-01-13 13:00:07.001]

*Note: Sigil ~N for naive date times

Question 31

Enum.empty?([1]) || 1

Answer 31

=> 1

*Note: Returns the second expression only if the first one is false or nil

Question 32

function_exported?(

Calc,

:add,

2

)

Answer 32

=> false

*Note: Returns true if module is loaded and contains a public function with the given arity.

Question 33

~W(cat dog bird)a

Answer 33

=> [:cat, :dog, :bird]

*Note: modifier a - words in the list are atoms.

Question 34

~w(cards config test.exs)

Answer 34

=> [“cards”, “config”, “test.exs”]