How should we teach a new language to folks that already know how to program? How do we use what we already know to leapfrog the learning process? Based on my personal experience and snippets of natural language theory, we will try to explore the cheats and pitfalls when learning a new programming language, but also dig into how we can make it easier.

1. @pati_gallardo
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@pati_gallardo
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2. @pati_gallardo
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To learn the basics - write an application you know
To learn the middle and remove the accent, maintain it with the feedback of a native speaker
2

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How do you learn a new
programming language?

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I tried to learn C#
You might too today

5. @pati_gallardo
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Where to start?
Write some code Get environmentTake notes
Videos / BooksFreak out
Procrastinate Ask on TwitterMake flow diagram

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Thoughts On Learning
A New Programming Language
Trying to learn C#
Patricia Aas
OOP 2020

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Patricia Aas - Trainer & Consultant
C++ Programmer, Application Security
Currently : TurtleSec
Previously : Vivaldi, Cisco Systems, Knowit, Opera Software
Master in Computer Science - main language Java
Pronouns: she/her

8. @pati_gallardo
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@pati_gallardo
The Genealogy of
programming languages

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9@pati_gallardo
Cross
Pollination
Good? Bad? Both?

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1. #define DEBUG 1
2.
3. namespace Communication {
4. class Telephone {
5. bool log = false;
6.
7. Telephone() {
8. #if DEBUG
9. log = true;
10. #endif
11. }
12.
13. ~Telephone() {
14. log = false;
15. }
16. };
17. }
@pati_gallardo 10
1. #define DEBUG
2.
3. namespace Communication {
4. class Telephone {
5. bool log = false;
6.
7. Telephone() {
8. #if DEBUG
9. log = true;
10. #endif
11. }
12.
13. ~Telephone() {
14. log = false;
15. }
16. }
17. }
Which
Programming
Language is
this?
What about
this?

11. @pati_gallardo
TurtleSec
1. #define DEBUG 1
2.
3. namespace Communication {
4. class Telephone {
5. bool log = false;
6.
7. Telephone() {
8. #if DEBUG
9. log = true;
10. #endif
11. }
12.
13. ~Telephone() {
14. log = false;
15. }
16. };
17. }
@pati_gallardo 11
1. #define DEBUG
2.
3. namespace Communication {
4. class Telephone {
5. bool log = false;
6.
7. Telephone() {
8. #if DEBUG
9. log = true;
10. #endif
11. }
12.
13. ~Telephone() {
14. log = false;
15. }
16. }
17. }
telephone.cpp
Telephone.cs
C++
C#

12. @pati_gallardo
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12@pati_gallardo
Evil Twin

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@pati_gallardo
How do you
learn a
language?

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Telephone Teléfono?
English
Spanish
Cognates
Same Origin, Form and Meaning

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Much Mucho?
English
SpanishSame Form and Meaning
False Cognates
Not Same Origin!

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16@pati_gallardo
Cognates or False
Cognates?
Does it matter?
Your mental shortcuts
are working!

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C# : An Imperative C-like language?
1. var list = new List<int>(){ 40, 5, 9, 39, 19 };
2.
3. for (int i = 0; i < list.Count; i++) {
4. Console.WriteLine(list[i]);
5. }
6.
7. foreach (var item in list) {
8. Console.WriteLine(item);
9. }
@pati_gallardo 17
No Surprises

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C# : A Functional Lisp-like language?
1. var list = new List<int>(){ 40, 5, 9, 39, 19 };
2.
3. list
4. .Where(s => s < 10)
5. .ToList()
6. .ForEach(s => Console.WriteLine(s));
@pati_gallardo 18
No Surprises?

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Pigg Pig?
Norwegian
English
False Friends
“I had bad pigs in my tires”
Same Form
Stud / Nail
Not Same Meaning!

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20@pati_gallardo
False Friends
Bad Assumptions
Your mental shortcuts
are hurting you
Drift in Meaning
Special case of
False Friends

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Frokost Frokost?
Norwegian
Danish
LunchDrift in Meaning
Same Origin and Form
Breakfast
Not Same Meaning!

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std::list List?
C++
C#
ArrayList/
Vector
Not Same Meaning!
Same Origin and Form
Linked List
Drift in Meaning

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FormMeaning
Origin
Cognates
False Friends
False Cognates
Drift in MeaningDrift in Form
I’ll figure it out
Trip me up

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@pati_gallardo
How you learn
depends on what
you know?

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25@pati_gallardo
First language Scheme (Lisp)
I know Java - university
I know C++ and C
I have coded in probably 10-15
other languages.
Examples: Perl, Python, JavaScript
Programming for almost 20 years
So what do I know?

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@pati_gallardo
You can’t start
from scratch

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What to skip?
Languages inherit from each other
What is normal? What is different?
Danger: False Friends
Danger: Unknown Unknowns

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Plan
Skip over Cognates
For loop, break, continue, if, else…
If it’s “normal”, skip it

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@pati_gallardo
How do you know that you’re
not missing things? Skim?

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Learn the basics
Find surprises
Too much
repetition
Cognates

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Namespaces
Defines
Drift in Meaning

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1. namespace PackageName {
2. public class ClassName {
3. // Class definition
4. }
5. }
[C++] Namespaces
Recognition
Language
C#More like C++
modules really?
Drift in Meaning

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[C & C++] C# has defines!
1. #define HERE_I_AM
2. using NUnit.Framework;
3.
4. public class Preprocessor {
5. [Test]
6. public void TestPreprocessor() {
7. #if HERE_I_AM
8. Assert.Pass();
9. #else
10. Assert.Fail();
11. #endif
12. }
13. }
@pati_gallardo 33
N really though.
No preprocessor
Drift in Meaning

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34@pati_gallardo
Operator Overloading
Optional Arguments
Named Parameters
Struct Value Type
Cognates

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[C++] Operator Overloading Use
1. Box first = new Box(new Point(1, 1), 3, 2);
2. Box second = new Box(new Point(3, 4), 3, 3);
3. Box boundingBox = first + second;
@pati_gallardo 35
Some constructs are quite elegant
with operator overloading

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Bounding box
x = 1
y = 1
width = 5
height = 6
(1,1)
(3,4)
Box boundingBox = first + second;
first
second

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[C++] Operator Overloading Definition
1. public static Box operator +(Box left, Box right) {
2. Point top =
3. new Point(Math.Min(left.top().x, right.top().x),
4. Math.Min(left.top().y, right.top().y));
5. Point bottom =
6. new Point(Math.Max(left.bottom().x, right.bottom().x),
7. Math.Max(left.bottom().y, right.bottom().y));
8. int width = bottom.x - top.x;
9. int height = bottom.y - top.y;
10. return new Box(top, width, height);
11. }
@pati_gallardo 37

38. @pati_gallardo
TurtleSec
[C++] Optional Arguments
1. public class OptionalArguments {
2. private static int increase(int x, int y = 2) {
3. return x + y;
4. }
5.
6. [Test]
7. public void TestOptionalArguments() {
8. Assert.AreEqual(5, increase(3));
9. }
10. }
@pati_gallardo 38

39. @pati_gallardo
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[Objective-C] Named Parameters
1. public class NamedParameters {
2. private static int named(int x, int y) {
3. return x + y;
4. }
5.
6. [Test]
7. public void TestNamedParameters() {
8. Assert.AreEqual(5, named(y: 3, x: 2));
9. }
10. }
@pati_gallardo 39

40. @pati_gallardo
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[C++] Struct - value type
1. struct Point {
2. public int x;
3. public int y;
4. }
@pati_gallardo 40
Similar in meaning to C++Drift in Form
In C++ structs are classes with default
public access - in C# structs are
classes that don’t allow inheritance
In C++ all types
are value types
Cognates

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41@pati_gallardo
Properties
Out Parameters
Drift in Form

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[Qt?] Properties
1. public class Properties {
2. public string ReadWriteProperty { get; set; } = "Hello";
3. public string ReadOnlyProperty { get; }
4. // Auto-implemented properties must have get accessors.
5. // public string WriteOnlyProperty { set; }
6. public string PrivateReadWriteProperty { private get; set; }
7. public string ReadPrivateWriteProperty { get; private set; }
8.
9. private string PrivateReadWriteField;
10. public string WrapField {
11. set => PrivateReadWriteField = value;
12. get => PrivateReadWriteField;
13. }
14. }
@pati_gallardo 42
Magic “value”

43. @pati_gallardo
TurtleSec
[C & C++] (Inline) Out Parameters
1. private static int outParam(int x, int y, out int mod) {
2. mod = x % y;
3. return x / y;
4. }
5.
6. [Test]
7. public void TestOutParameters() {
8. int quotient = outParam(25, 5, out var remainder);
9. Assert.AreEqual(0, remainder);
10. Assert.AreEqual(5, quotient);
11. }
@pati_gallardo 43
Passing int
by ref

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[] Null-conditional operators ?. and ?[]
1. int GetCoffee(List<Shop> coffeeShops, int index) {
2. // If there are any coffeeShops and
3. // if there is a shop at that index,
4. // please get me that coffee,
5. // if not, just get me 0
6. return coffeeShops?[index]?.Coffee ?? 0;
7. }
@pati_gallardo 44

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45@pati_gallardo
Destructor / Finalize
False Friends

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Point out false friends
C# finalizers (also called destructors!)
look like C++ destructors
but act like Java’s finalize()

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[C++ & Java] Destructor / Finalize
1. public class DestroyMe {
2. ~DestroyMe() {
3. // Might be called by the
4. // Garbage Collector
5. }
6. }
@pati_gallardo 47
More like Java
finalize
Drift in Meaning

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@pati_gallardo What are the semantics?

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Learn the middle
What’s the
middle?
Beyond
basic
syntax?

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[Java & C++] IDisposable
1. public class DisposeMe : IDisposable {
2. private FileStream fileStream;
3.
4. public void Dispose() {
5. fileStream?.Dispose();
6. }
7. }
@pati_gallardo 50
Similar to Javas
Closeable
Drift in Form
Same semantics
Different syntax

51. @pati_gallardo
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[Python] yield return (Generators)
1. public IEnumerable<int> YieldReturn() {
2. yield return 3;
3. yield return 4;
4. yield return 5;
5. }
6. [Test]
7. public void TestingYieldReturn() {
8. using var it = YieldReturn().GetEnumerator();
9. it.MoveNext();
10. Assert.AreEqual(3, it.Current);
11. it.MoveNext();
12. Assert.AreEqual(4, it.Current);
13. it.MoveNext();
14. Assert.AreEqual(5, it.Current);
15. }
@pati_gallardo 51

52. @pati_gallardo
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[Python, Java, C++] IEnumerable (Lazy Iterators)
1. // C# In Depth, Jon Skeet
2. // Lazy Evaluation
3. static IEnumerable<int> Fibonacci() {
4. int current = 0;
5. int next = 1;
6. while (true) {
7. yield return current;
8. int oldCurrent = current;
9. current = next;
10. next = next + oldCurrent;
11. }
12. }
@pati_gallardo 52

53. @pati_gallardo
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[?] Extension Methods (Extend 3-party Classes)
1. public class Target {}
2. public static class Extension {
3. public static void PrintHello(this Target t) {
4. Console.WriteLine("Hello World");
5. }
6. }
7. public class Test {
8. [Test]
9. public void TestExtension() {
10. Target target = new Target();
11. target.PrintHello();
12. }
13. }
@pati_gallardo 53

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@pati_gallardo
How do we teach?

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Use Terms People Recognize
Explain how this is different
But give folks a frame of reference
Delegate -> Fancy Function Pointer

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[C & C++] Delegates ( Fancy Function Pointers)
1. public class DelegateTest {
2. public delegate void printMe();
3. [Test]
4. public void TestExtension() {
5. printMe printHello =
6. delegate {
7. Console.WriteLine("Hello World!");
8. };
9. printHello();
10. }
11. }
@pati_gallardo 56
Function Pointer
Type
Function
DefinitionUsing Function
Pointer

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[C & C++] Delegates ( Fancy Function Pointers)
1. printMe first = delegate { Console.WriteLine("Hello"); };
2. printMe second = delegate { Console.WriteLine("World"); };
3.
4. var helloWorld = first + second;
5. helloWorld();
57
Composable
Function Pointers!
Operator + defined on
“function pointers”
@pati_gallardo

58. @pati_gallardo
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[C++ Qt] Events (Event Handlers)
1. EventHandler handler =
2. delegate {
3. Console.WriteLine("Hello Event!");
4. };
5. handler?.Invoke(this, EventArgs.Empty);
@pati_gallardo 58

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59@pati_gallardo
Non Zero Based Array
Nullable Types
Decimal
What about
surprises?
128 bit floating
point type with
28-29 significant
digit precision
What else
have I
missed?

60. @pati_gallardo
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Non Zero Based Array
1. Array array = Array.CreateInstance(typeof(int),
2. new[] {2},
3. new[] {42});
4. array.SetValue(5, 42);
5. array.SetValue(6, 43);
6. Assert.AreEqual(2, array.GetLength(0));
7. Assert.AreEqual(42, array.GetLowerBound(0));
8. Assert.AreEqual(43, array.GetUpperBound(0));
9. Assert.AreEqual(5, array.GetValue(42));
10. Assert.AreEqual(6, array.GetValue(43));
@pati_gallardo 60
I mean…. Wat?

61. @pati_gallardo
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Nullable Types
1. bool? maybe = null;
2.
3. if (maybe ?? true)
4. Console.WriteLine("Print Me!");
5.
6. maybe = false;
7.
8. if (!maybe ?? false)
9. Console.WriteLine("Print me too!");
@pati_gallardo 61
Maybe??

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62@pati_gallardo
Anonymous Types
ExpandoObject
JavaScript
Love

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[JavaScript] Anonymous Types
1. var gilmoreGirls =
2. new[] {
3. new { Name = "Loralai", Age = "36" },
4. new { Name = "Rory", Age = "20" }
5. };
@pati_gallardo 63
If you squint it looks
a bit like JS objects

64. @pati_gallardo
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[JavaScript] ExpandoObject
1. public delegate void printMe();
2.
3. [Test]
4. public void Test() {
5. dynamic expando = new ExpandoObject();
6. // Add a field
7. expando.GilmoreGirl = "Rory";
8. Assert.AreEqual("Rory", expando.GilmoreGirl);
9. // Add a function
10. printMe order = delegate { Console.WriteLine("Coffee!"); };
11. expando.getCoffee = order;
12. expando.getCoffee();
13. }
14.
@pati_gallardo 64
Full on JS!

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Killer features
Why C#?
N just
Nice To
Have

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Why would I choose C#?
Platform Integration
LINQ

67. @pati_gallardo
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@pati_gallardo
How do we learn?

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Rewrite an application you have written already
Focus on the language
and n the application
What are the Unknown
Unknowns?
Hard to get confident

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FormMeaning
Origin
Cognates
False Friends
False Cognates
Drift in MeaningDrift in Form
Unknown
Unknowns!
How do you find out
what you don’t know?

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The best way to learn
a programming language is
to make something interesting
next to someone who’s
knowledgeable and kind

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1. #define DEBUG 1
2.
3. namespace Communication {
4. class Telephone {
5. bool log = false;
6.
7. Telephone() {
8. #if DEBUG
9. log = true;
10. #endif
11. }
12.
13. ~Telephone() {
14. log = false;
15. }
16. };
17. }
@pati_gallardo 71
1. #define DEBUG
2.
3. namespace Communication {
4. class Telephone {
5. bool log = false;
6.
7. Telephone() {
8. #if DEBUG
9. log = true;
10. #endif
11. }
12.
13. ~Telephone() {
14. log = false;
15. }
16. }
17. }
telephone.cpp
Telephone.cs
C++
C#
You can have an
accent in code!
Or “not idiomatic”

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Where to start?
Procrastinate
Anything that gets you
out of this is good
Maybe even
submitting a talk
to a conference?

73. @pati_gallardo
TurtleSec
@pati_gallardo

74. @pati_gallardo
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Questions?
Photos from pixabay.com
Patricia Aas, TurtleSec

75. @pati_gallardo
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@pati_gallardo
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