For the CodeMash Precompiler

1. Learning Go From Hello
World to Web Service
Eric Potter

2. Learning Go From Hello
World to Web Service
Eric Potter

3. Background
Before we go
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4. Creators
Rob Pike
• Worked at Bell
Labs and Google
• co-creator of
UTF-8
Ken Thompson
• Designed and
implemented the
original Unix
Robert Griesemer
• Worked on
Google's V8
JavaScript engine
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5. Fast
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7. Tools
All systems go
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8. Installation
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9. Go CLI
• go run
• go build
• go mod init
• go test
• go get
• go fmt
• etc
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10. IDEs
VS Code GoLand ($)
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11. Hello World
Demo
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12. Hello World
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13. Types
Go your own way
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14. Basic Types
• bool
• string
• int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64
• rune // alias for int32 that represents a Unicode code point
• float32, float64
• complex64, complex128
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15. Variable Declaration
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16. Syntax
Let it go
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17. Terse
; ( )
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18. Notable Omissions
++i
do {}
while
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19. Function Syntax
C#
public <returnType> <name> (<args>)
Go
func <name> (<args>) <returnType>
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20. Fizz Buzz
Demo
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21. Fizz Buzz
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22. Questions
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23. Exercise 1
Euler 1
1) If we list all the natural numbers below 10 that are multiples of 3
or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.
Find the sum of all the multiples of 3 or 5 below 1000.
2) The Math.Sin values for 2 is positive and the value for 5 is
negative. Print the sum of the positive sine values from the input
between 0 and 10.
If you get done, try Euler 2 (https://projecteuler.net/problem=2)
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24. Euler 1
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26. Arrays
Go home
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27. Declaring Arrays
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28. Accessing Array Elements
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30. Iterate over an Array
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31. The size is part of the type
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32. Slices
Go home
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34. Dynamic Sizing
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35. Ranges
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36. Classes
Go home
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37. Classes
Go home
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Packages & Structs

38. Defining a Struct
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41. Associating Functions with Structs
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42. Interfaces
Go home
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43. Defining an Interface
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44. Questions
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45. Exercise 2
Create a GIF
Using the image/gif and image/color packages, create a gif of a
checker board.
Using the same libraries, create an animated gif of a sine wave.
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46. Concurrency
You go your way,
I’ll go mine
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47. Concurrent Functions
Demo
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49. Channels
Go change the
channel
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50. TextEntryWithTimeout
Demo
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51. TextEntryWithTimeout
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52. WaitGroups
Go wait in the corner
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54. Questions
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55. Exercise 3
Create a GIF Concurrently
Modify your code that creates a sine wave gif to create the file
concurrently while the user enters the output file name.
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58. Web Services
Go on
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59. net/http Package
• The core functionality is in a standard library.
• There are packages like gin that provide structure.
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60. net/http
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61. Data Access
Go get it
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62. database/sql
• Go uses a driver and plugin model.
• There are larger frameworks like Gorm
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63. database/sql
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64. Questions
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65. Exercise 4
Web Services
Create a webservice that returns the sine of a given number.
Create a webservice that returns your sine wave GIF
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66. Thank you
Eric Potter • @pottereric •
HumbleToolsmith.com
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