elixir KERNEL 2

Question 1

is_map(%{})

Answer 1

=> true

Question 2

What type of Error raised when executing? not nil

Answer 2

ArgumentError

*Note: Arguments must be a boolean

Question 3

length([a: 1, b: 2])

Answer 3

=> 2

Question 4

hd([5, 6, 7])

Answer 4

=> 5

Question 5

is_float(1.2)

Answer 5

=> true

Question 6

What type of Error raised when executing?

elem({}, 0)

Answer 6

ArgumentError

Question 7

is_map(%Range{})

Answer 7

=> true

Question 8

true and “hello”

Answer 8

=> “hello”

Question 9

is_nil(nil)

Answer 9

=> true

Question 10

to_string(12.3)

Answer 10

=> “12.3”

Question 11

false and “hello”

Answer 11

=> false

Question 12

rem(8, -7)

Answer 12

=> 1

Question 13

elem({1, 2, :hello}, 1)

Answer 13

=> 2

Question 14

apply(Kernel, :byte_size, [“cat”])

Answer 14

=> 3

Question 15

is_function(fn(x) -> x + 1 end)

Answer 15

=> true

Question 16

is_integer(28) == is_number(2.7)

Answer 16

=> true

Question 17

tuple = {:clever, “bunny”}

put_elem(tuple, 0, “funny”)

Answer 17

=> {“funny”, “bunny”}

Question 18

inspect(:hello)

Answer 18

=> “:hello”

Question 19

byte_size(«1, 2»)

Answer 19

=> 2

Question 20

inspect(‘bar’)

Answer 20

=> “‘bar’”

Question 21

not false

Answer 21

=> true

Question 22

inspect [1, 2, 3], limit: 2

Answer 22

=> “[1, 2, …]”

Question 23

self() |> is_pid()

Answer 23

=> true

Question 24

iex> x = 1

iex> binding()

Answer 24

iex => [x: 1]

*Note: Returns the binding for the given context as a keyword list

Question 25

is_list([])

Answer 25

=> true

Question 26

to_string([1, 2, 3])

Answer 26

=> «1, 2, 3»

Question 27

true or false

Answer 27

=> true

Question 28

inspect(15, base: :hex)

Answer 28

=> “OxF”

Question 29

What type of Error raised when executing?

:hello or true

Answer 29

** (BadBooleanError)
expected a boolean on left-side of “or”,
got: :hello

Question 30

to_string(:hello)

Answer 30

=> “hello”

Question 31

map_size(%{a: 1})

Answer 31

=> 1

Question 32

to_string(123)

Answer 32

=> “123”

Question 33

max(1, :a)

Answer 33

=> :a

*Note: term ordering: number < atom < reference < function < port < pid < tuple < map < list < bitstring

Question 34

round(4.49)

Answer 34

=> 4

Question 35

node() |> is_binary()

Answer 35

=> false
*Note: Returns an atom representing the name of the local node. If the node is not alive, :nonode@nohost is returned instead

Question 36

What type of error would be raised when evaluating?

1 and true

Answer 36

** (BadBooleanError)
expected a boolean on left-side of “and”,
got: 1

Question 37

iex> x = 1
iex> x = 2
iex> binding()

Answer 37

=> [x: 2]

*Note: Returns the binding for the given context as a keyword list.

Question 38

What type of error is raised when executing?

rem(8, 0.8)

Answer 38

** (ArithmeticError) bad argument in arithmetic expression

:erlang.rem(8, 0.8)

Question 39

1 && 4 == 1 and 4

Answer 39

=> false

*Note: and accepts boolean as a first argument. && accepts any expression as the first argument

Question 40

fun = fn x -> max(x, 3) end

apply(fun, [2])

Answer 40

=> 3

Question 41

Agent.start(fn() -> [] end) |> is_tuple()

Answer 41

=> true

*Returns {:ok, #PID}

Question 42

make_ref() |> is_reference()

Answer 42

=> true

Question 43

if is_bitstring("bunny") do 
    "bunny is a bitstring"
else
    "not a bitstring"
end

Answer 43

=> “bunny is a bitstring”

Question 44

min(self(), :hello)

Answer 44

=> :hello

*Note: term ordering: number < atom < reference < function < port < pid < tuple < map < list < bitstring

Question 45

if div(8, 2) == 3, do: “yes”

Answer 45

=> nil

*Note nil is returned when condition passed to if doesn’t return true

Question 46

What type of Error raised when executing?

to_string({:ok, “hello”})

Answer 46

** (Protocol.UndefinedError)

protocol String.Chars not implemented for {:ok, “hello”} of type Tuple

Question 47

inspect(
“hello” <> «0»,
binaries: :as_strings
)

Answer 47

=> “"hello\0"”

Question 48

inspect(
“h” <> «0»,
binaries: :as_binaries
)

Answer 48

=> “«104, 0»”

Question 49

iex> x = 1
iex> y = 2
iex> binding()

Answer 49

=> [x: 1, y: 2]

*Note: Returns the binding for the given context as a keyword list.

Question 50

What type of Error is raised when executing?

hd([])

Answer 50

ArgumentError

Question 51

true and 4 and 5

Answer 51

** (BadBooleanError)
expected a boolean on left-side of “and”,
got: 4

Question 52

byte_size(«145::24, 5::4»)

Answer 52

=> 4
*Note: if the number of bits in bitstring is not divisible by 8, the resulting number of bytes will be rounded up (by excess)

Question 53

is_function(fn(x) -> x + 1 end, 2)

Answer 53

=> false

*Note: Returns true if term is a function that can be applied with arity number of arguments; otherwise returns false

Question 54

true or “hello”

Answer 54

=> true
*Note: If the first argument is true, true is returned; otherwise, the second argument is returned. Requires only the first argument to be a boolean since it short-circuits.