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Basic Clojure MCQ

1. A Clojure sequence is a Java

Iterable

Iterator

Map

List

Answer

Correct Answer: Iterator

Note: This Question is unanswered, help us to find answer for this one

2. What is the Closure equivalent to ClassName.class in Java?

(ClassName.class)

Class.name

ClassName.CLASS

ClassName

Answer

Correct Answer: ClassName

Note: This Question is unanswered, help us to find answer for this one

3. How many ways can you safely share mutable data using Clojure?

Answer

Correct Answer: 3

Note: This Question is unanswered, help us to find answer for this one

4. What's the value returned by... (let [[x y [z]] [2 4 [8 9]]] (list x y z))

[2 4 [8 9]]

(2 4 (8 9))

(2 4 8)

Answer

Correct Answer: (2 4 8)

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5. The Clojure reader can be extended using _____

reader macros

XML

metadata

tagged literals

Answer

Correct Answer: tagged literals

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6. Refs _____

provide thread-local variable bindings

manage independent, asynchronous changes to a single location

provide thread-isolated transactions

manage independent, synchronous changes to a single location

Answer

Correct Answer: provide thread-isolated transactions

Note: This Question is unanswered, help us to find answer for this one

7. The application of advice or other aspect transformations is often called __________.

wrapping

weaving

advising

profiling

Answer

Correct Answer: weaving

Note: This Question is unanswered, help us to find answer for this one

8. A _______ is a construct that suspends some body of code, evaluating it upon demand, when it is "deref"erenced.

future

deliver

promise

delay

Answer

Correct Answer: delay

Note: This Question is unanswered, help us to find answer for this one

9. If you want to create class that extends another class, you must use _____

deftype

defrecord

reify

gen-class

Answer

Correct Answer: gen-class

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10. What provides synchronous changes to a single, thread-local value?

Refs

Var

Agents

Atoms

Answer

Correct Answer: Var

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11. Atoms _____

provide thread-isolated transactions

provide thread-local variable bindings

manage independent, asynchronous changes to a single location

manage independent, synchronous changes to a single location

Answer

Correct Answer: manage independent, synchronous changes to a single location

Note: This Question is unanswered, help us to find answer for this one

12. (.split "Java String" " ") returns

A Java array of strings

Invalid operation for string

Syntax error

A lazy-sequenced array of strings

Answer

Correct Answer: A Java array of strings

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13. Agents _____

manage independent, asynchronous changes to a single location

provide thread-isolated transactions

manage independent, synchronous changes to a single location

provide thread-local variable bindings

Answer

Correct Answer: manage independent, asynchronous changes to a single location

Note: This Question is unanswered, help us to find answer for this one

14. What does the "contains?" function work on?

Sets

All of these

Vectors

Maps

Answer

Correct Answer: All of these

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15. Clojure is hosted on the JVM (Java Virtual Machine) and can use any Java library.

FALSE

True

Answer

Correct Answer: True

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16. Which statement best describes protocols in Clojure?

A protocol defines how two programs communicate over a computer network.

Clojure provides several macros that make it easy to implement various network protocols.

A protocol defines an interface. But unlike Java interfaces, which must be specified when a class is created, protocols can be attached to a class at any time.

Clojure uses the term "protocol" to refer to what Java calls an "interface".

Answer

Correct Answer: A protocol defines an interface. But unlike Java interfaces, which must be specified when a class is created, protocols can be attached to a class at any time.

Note: This Question is unanswered, help us to find answer for this one

17. Which of the following code fragments evaluates to 5?

({:a 1 :b 3 :c 5} :c)

(:c {:a 1 :b 3 :c 5})

All of the above

(get {:a 1 :b 3 :c 5} :c)

Answer

Correct Answer: All of the above

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18. True or False? Sets are collections of unique items. They are better than lists and vectors when duplicates aren't allowed.

False

True

Answer

Correct Answer: True

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19. Clojure documentation can be accessed

All of the above

via the doc function

through the clojure.org website

on clojuredocs.org

Answer

Correct Answer: All of the above

Note: This Question is unanswered, help us to find answer for this one

20. In Clojure, you can create a new class using _____

All of the above

deftype

gen-class

proxy

Answer

Correct Answer: All of the above

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21. Which is a type of collection in Clojure?

None of these

All of these

Set

Vector

Answer

Correct Answer: All of these

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22. What does the REPL tool do?

Read-enter-print look

Read-eval-part loop

Repeat-eval-pair loop

Read-eval-print loop

Answer

Correct Answer: Read-eval-print loop

Note: This Question is unanswered, help us to find answer for this one

23. Clojure strings are Java Strings and are represented in exactly the same way, delimited by double quotes.

True

FALSE

Answer

Correct Answer: True

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24. Which of the following Clojure fragments calculates (4+2)*(5-3)?

(* (+ 4 2) (- 5 3))

(+ 4 2 (* (- 5 3)))

4 2 + 5 3 - *

4+2*(5-3)

Answer

Correct Answer: (* (+ 4 2) (- 5 3))

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25. A function can be stored in a var or passed as an argument to other functions.

True

False

Answer

Correct Answer: True

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26. True or False? Arity is the number of arguments a function can handle.

True

False

Answer

Correct Answer: True

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27. What is the syntax of the "if" function?

(condition-if-then-expr-else expr)

(if condition then-expr else-expr)

(condition if then-expr else-expr)

(condition to-expr else-expr)

Answer

Correct Answer: (if condition then-expr else-expr)

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28. True or False? In Clojure a symbol can contain characters that most imperative languages don't allow in variable names. (Example: in Clojure you can have a symbol with the name +a-.)

False

True

Answer

Correct Answer: True

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29. True or False? Clojure a functional language.

False

True

Answer

Correct Answer: True

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30. True or False? The Clojure language is homoiconic.

True

False

Answer

Correct Answer: True

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31. Does Clojure have a metadata system that allows for annotation of symbols and collections?

True

False

Answer

Correct Answer: True

Note: This Question is unanswered, help us to find answer for this one

32. Leiningen uses _____ to locate and manage project dependencies

GitHub

SourceForge

Maven

Ivy

Answer

Correct Answer: Maven

Note: This Question is unanswered, help us to find answer for this one

33. What is the function that evaluates a single argument form?

var

test

eval

defn

Answer

Correct Answer: eval

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34. Which is an example of a Clojure function call?

(method-name arg1 arg2 arg3)

function-name (arg1, arg2, arg3)

(function-name arg1 arg2 arg3)

methodName(arg1, arg2, arg3)

Answer

Correct Answer: (function-name arg1 arg2 arg3)

Note: This Question is unanswered, help us to find answer for this one

35. What type does the following code result in? {:a 1 "b" 2}

List

Vector

Map

Array

Answer

Correct Answer: Map

Note: This Question is unanswered, help us to find answer for this one

36. How do you create an anonymous function?

#(single-expression)

#(double-expression)

#{items}

prefix#

Answer

Correct Answer: #(single-expression)

Note: This Question is unanswered, help us to find answer for this one

37. Collections that classically support last-in, first-out (LIFO) semantics are called ____________.

vectors

stacks

indices

contains

Answer

Correct Answer: stacks

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38. True or False? Clojure programs only support some Java classes and interfaces.

False

True

Answer

Correct Answer: False

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39. What is significant about function names that end with a "!"?

All functions that mutate some state must end with a "!", or else you will get a compiler error.

It warns users that the function is deprecated.

It is a convention that indicates the function mutates some state.

It serves as a warning that the function in question may produce an unstable result.

Answer

Correct Answer: It is a convention that indicates the function mutates some state.

Note: This Question is unanswered, help us to find answer for this one

40. How do you add metadata to a symbol or collection?

(class-name. args)

#"pattern"

{key-value-pairs}

^{key-value-pairs} object

Answer

Correct Answer: ^{key-value-pairs} object

Note: This Question is unanswered, help us to find answer for this one

41. lib-noir, Ring, and Compojure are all examples of Clojure:

REST service modules

SOAP service modules

API service modules

JSON service modules

HTTP service modules

Answer

Correct Answer: HTTP service modules

Note: This Question is unanswered, help us to find answer for this one

42. To calculate the average of some numbers in Clojure, your code would look like this:

def average (numbers) numbers.inject(: +) / numbers.length end

(defn average [numbers] (/ (apply + numbers) (count numbers)))

def average (numbers): return sum( numbers) / len( numbers)

public static double average (double[] numbers) { double sum = 0; for (int i = 0; i < numbers.length; i + +) { sum + = numbers[ i]; } return sum / numbers.length; }

Answer

Correct Answer: (defn average [numbers] (/ (apply + numbers) (count numbers)))

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43. What are sequences?

Specific collections

Concrete lists

Logical views of collections

Ordered codes

Answer

Correct Answer: Logical views of collections

Note: This Question is unanswered, help us to find answer for this one

44. The map function is used to _____

apply a function to all elements in a collection and return a sequence of the results

All of the above

aggregate the elements in a collection using a given function and return the result as a single value

create a new Map object containing the specified elements

Answer

Correct Answer: apply a function to all elements in a collection and return a sequence of the results

Note: This Question is unanswered, help us to find answer for this one

45. Which statement about Clojure macros is true?

Macros are basically a glorified parameterizable search-replace mechanism. They are error prone, and should be avoided at all costs.

Macros provide an ad-hoc mechanism for improving the performance of critical code.

Macros allow programmers to specify program transformations that occur during compile time.

Macros are useful, but Clojure's implementation of them is very limited.

Answer

Correct Answer: Macros allow programmers to specify program transformations that occur during compile time.

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46. Stack abstraction is supported in Clojure via what three operations?

conj, pop, peek

get, find, pop

find, conj, get

get, nth, find

Answer

Correct Answer: conj, pop, peek

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47. A built-in Clojure "operation" may be implemented as a...

Macro

All of these

Special Form

Function

Answer

Correct Answer: All of these

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48. :foo is an example of a(n) _____

atom

keyword

variable name

symbol

Answer

Correct Answer: keyword

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49. If you are already using Java or another JVM language for RDBMS work, it’s likely that you’re using ______________, easily the most popular Java object/ relational mapping library.

Hibernate

Korma

SLIME

Entity

Answer

Correct Answer: Hibernate

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50. What type does the following code result in? [1 2 3 4]

List

Map

Array

Vector

Answer

Correct Answer: Vector

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51. What are the 3 phases Clojure code is processed in?

Read-time, gather-time, run-time

Read-time, compile-time, load-time

There are actually 4 phases.

Read-time, compile-time, run-time

Answer

Correct Answer: Read-time, compile-time, run-time

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52. The reduce function is used to _____

apply a function to all elements in a collection and return a sequence of the results

All of the above

aggregate the elements in a collection using a given function and return the result as a single value

substract a given amount from an integer value

Answer

Correct Answer: aggregate the elements in a collection using a given function and return the result as a single value

Note: This Question is unanswered, help us to find answer for this one

53. True or False? A lazy-sequence can hold all the possible calculations of the Fibonacci sequence.

False

True

Answer

Correct Answer: True

Note: This Question is unanswered, help us to find answer for this one

54. True or False? Metadata is data about data, and has no effect on the 'host' data.

False

True

Answer

Correct Answer: True

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55. Clojure provides several "persistent" data structures. Objects of these classes are _____

implemented in a way that makes them robust in case of memory errors

immutable

stored in a database

serializable

Answer

Correct Answer: immutable

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56. The following code will evaluate to true? (defn +++ [n] (+ (inc n) 1)) (= (+++ 1) 3)

True

Can't define a reserved symbol

+ is reserved and can't be re-defined

False

Syntax error

Answer

Correct Answer: True

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57. How would you want to create a new Atom with an initial value <value>?

(new Atom <value>)

(new-atom value)

(new 'Atom <value>)

(atom <value>)

(make-atom <value)

Answer

Correct Answer: (atom <value>)

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58. Clojure is primarily an imperative language.

True

False

Answer

Correct Answer: False

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59. What is generally the first step in deploying your Clojure web application?

Installing and configuring Leiningen or setting up and configuring an app server.

Copying the .war file your build process is producing to your server.

Restarting the application

Reverting your application's .war file to a prior version.

Answer

Correct Answer: Installing and configuring Leiningen or setting up and configuring an app server.

Note: This Question is unanswered, help us to find answer for this one

60. ________ evaluates all of the expressions provided to it in order and yields the last expression's value as its value.

def

let

Answer

Correct Answer: do

Note: This Question is unanswered, help us to find answer for this one

61. A(n) ________ is a named Emacs object that represents something editable, usually a file in your filesystem, but also the Clojure REPL or debugger, for example.

Window

Buffer

inferior-lisp

paredit

Answer

Correct Answer: Buffer

Note: This Question is unanswered, help us to find answer for this one

62. A multimethod is created using a form, and implementations of a multimethod are provided by ___ form.

defmulti, defmethod

derive, make-heiracrchy

fill, fill-dispatch

defmethod, defmulti

Answer

Correct Answer: defmulti, defmethod

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63. True or False? Clojure is NOT an imperative language.

True

False

Answer

Correct Answer: True

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64. What is the literal syntax for maps?

{:a 1 :b 2}

#{:a 1 :b 2}

[:a 1 :b 2]

Answer

Correct Answer: {:a 1 :b 2}

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65. In many object-oriented languages, ________________ is a way to decouple a class from other objects upon which that class depends.

dependency injection

strategy pattern

chain of responsibility

the template method

Answer

Correct Answer: dependency injection

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66. What is the conventional first and last character used to name vars intended to be bound to new, thread-local values?

(

Answer

Correct Answer: *

Note: This Question is unanswered, help us to find answer for this one

67. ________ is a very low-level looping and recursion operation that is usually not necessary.

reduce

map

recur

leap

Answer

Correct Answer: recur

Note: This Question is unanswered, help us to find answer for this one

68. You can use ___________ whenever you like if you need a unique symbol, but its primary role is in helping us write hygienic macros.

important-value

defmacro

hygienic

gensym

Answer

Correct Answer: gensym

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69. (= (map + '(1 2 3)) 3)

False

True

(1 2 3)

Answer

Correct Answer: False

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70. True or False? Function definitions must appear before they're first used.

True

False

Answer

Correct Answer: True

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71. Which statement about -> and comp is true?

-> is a macro while comp is a higher order function

-> and comp are exactly the same, except the parameters are in the opposite order

-> is not a valid identifier in clojure, but comp is

comp is a macro while -> is a higher order function

Answer

Correct Answer: -> is a macro while comp is a higher order function

Note: This Question is unanswered, help us to find answer for this one

72. What's a difference between quote (') and syntax-quote (`) macro characters?

There is no difference between quote (') and syntax-quote (`)

Syntax-quote (`) fully qualifies symbols, while quote (') doesn't

Quote (') fully qualifies symbols, while syntax-quote (`) doesn't

Answer

Correct Answer: Syntax-quote (`) fully qualifies symbols, while quote (') doesn't

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73. In Clojure, tail-call optimization is _____

done for every call which is in a tail position

only done for simple recursion

impossible

not supported natively by the compiler, but could be simulated using thunks, trampolines, and macros.

Answer

Correct Answer: not supported natively by the compiler, but could be simulated using thunks, trampolines, and macros.

Note: This Question is unanswered, help us to find answer for this one

74. To represent a boxed decimal in Clojure, you would use ____________.

java.lang.Double

float

Fixnum

Float

Answer

Correct Answer: java.lang.Double

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75. Locks _____

provide thread-local variable bindings

are a low-level construct that should be avoided in most cases

manage independent, asynchronous changes to a single location

provide thread-isolated transactions

Answer

Correct Answer: are a low-level construct that should be avoided in most cases

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76. True or False? (reset!) is used to set the value of an atom.

True

False

Answer

Correct Answer: True

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77. Which statement regarding Clojure "forms" is true?

Every function call is a form, but not every form is a function call.

Every form is a function call, but not every function call is a form.

The terms "function call" and "form" are completely interchangeable.

A form is like a function call, except it invokes a macro instead.

Answer

Correct Answer: Every function call is a form, but not every form is a function call.

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78. For the following code to evaluate without error, what needs to be added? (def regex "<a>(.*)</a>") (re-seq regex "<a>Ryan Kelker</a>")

@ symbol when defining regex

# symbol before the string in regex

# symbol before regex in (re-seq)

Nothing. The syntax is correct

# symbol before regex and after def

Answer

Correct Answer: # symbol before the string in regex

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Basic Clojure MCQ

1. A Clojure sequence is a Java

2. What is the Closure equivalent to ClassName.class in Java?

3. How many ways can you safely share mutable data using Clojure?

4. What's the value returned by... (let [[x y [z]] [2 4 [8 9]]] (list x y z))

5. The Clojure reader can be extended using _____

6. Refs _____

7. The application of advice or other aspect transformations is often called __________.

8. A _______ is a construct that suspends some body of code, evaluating it upon demand, when it is "deref"erenced.

9. If you want to create class that extends another class, you must use _____

10. What provides synchronous changes to a single, thread-local value?

11. Atoms _____

12. (.split "Java String" " ") returns

13. Agents _____

14. What does the "contains?" function work on?

15. Clojure is hosted on the JVM (Java Virtual Machine) and can use any Java library.

16. Which statement best describes protocols in Clojure?

17. Which of the following code fragments evaluates to 5?

18. True or False? Sets are collections of unique items. They are better than lists and vectors when duplicates aren't allowed.

19. Clojure documentation can be accessed

20. In Clojure, you can create a new class using _____

21. Which is a type of collection in Clojure?

22. What does the REPL tool do?

23. Clojure strings are Java Strings and are represented in exactly the same way, delimited by double quotes.

24. Which of the following Clojure fragments calculates (4+2)*(5-3)?

25. A function can be stored in a var or passed as an argument to other functions.

26. True or False? Arity is the number of arguments a function can handle.

27. What is the syntax of the "if" function?

28. True or False? In Clojure a symbol can contain characters that most imperative languages don't allow in variable names. (Example: in Clojure you can have a symbol with the name +a-.)

29. True or False? Clojure a functional language.

30. True or False? The Clojure language is homoiconic.

31. Does Clojure have a metadata system that allows for annotation of symbols and collections?

32. Leiningen uses _____ to locate and manage project dependencies

33. What is the function that evaluates a single argument form?

34. Which is an example of a Clojure function call?

35. What type does the following code result in? {:a 1 "b" 2}

36. How do you create an anonymous function?

37. Collections that classically support last-in, first-out (LIFO) semantics are called ____________.

38. True or False? Clojure programs only support some Java classes and interfaces.

39. What is significant about function names that end with a "!"?

40. How do you add metadata to a symbol or collection?

41. lib-noir, Ring, and Compojure are all examples of Clojure:

42. To calculate the average of some numbers in Clojure, your code would look like this:

43. What are sequences?

44. The map function is used to _____

45. Which statement about Clojure macros is true?

46. Stack abstraction is supported in Clojure via what three operations?

47. A built-in Clojure "operation" may be implemented as a...

48. :foo is an example of a(n) _____

49. If you are already using Java or another JVM language for RDBMS work, it’s likely that you’re using ______________, easily the most popular Java object/ relational mapping library.

50. What type does the following code result in? [1 2 3 4]

51. What are the 3 phases Clojure code is processed in?

52. The reduce function is used to _____

53. True or False? A lazy-sequence can hold all the possible calculations of the Fibonacci sequence.

54. True or False? Metadata is data about data, and has no effect on the 'host' data.

55. Clojure provides several "persistent" data structures. Objects of these classes are _____

56. The following code will evaluate to true? (defn +++ [n] (+ (inc n) 1)) (= (+++ 1) 3)

57. How would you want to create a new Atom with an initial value <value>?

58. Clojure is primarily an imperative language.

59. What is generally the first step in deploying your Clojure web application?

60. ________ evaluates all of the expressions provided to it in order and yields the last expression's value as its value.

61. A(n) ________ is a named Emacs object that represents something editable, usually a file in your filesystem, but also the Clojure REPL or debugger, for example.

62. A multimethod is created using a ________form, and implementations of a multimethod are provided by ___________ form.

63. True or False? Clojure is NOT an imperative language.

64. What is the literal syntax for maps?

65. In many object-oriented languages, ________________ is a way to decouple a class from other objects upon which that class depends.

66. What is the conventional first and last character used to name vars intended to be bound to new, thread-local values?

67. ________ is a very low-level looping and recursion operation that is usually not necessary.

68. You can use ___________ whenever you like if you need a unique symbol, but its primary role is in helping us write hygienic macros.

69. (= (map + '(1 2 3)) 3)

70. True or False? Function definitions must appear before they're first used.

71. Which statement about -> and comp is true?

72. What's a difference between quote (') and syntax-quote (`) macro characters?

73. In Clojure, tail-call optimization is _____

74. To represent a boxed decimal in Clojure, you would use ____________.

75. Locks _____

76. True or False? (reset!) is used to set the value of an atom.

77. Which statement regarding Clojure "forms" is true?

78. For the following code to evaluate without error, what needs to be added? (def regex "<a>(.*)</a>") (re-seq regex "<a>Ryan Kelker</a>")

62. A multimethod is created using a form, and implementations of a multimethod are provided by ___ form.