the-gpl

The Go Programming Language is a seminal programming language authored by Avengers: Alan A. A. Donovan and Brian W. Kernighan. This git repo is an attempt to share my learning from this book to showcase problems posed in the book and then some. The source-code by authors is on GitHub at gopl.io.

You can experience the deployed artifacts on the web as:

1. GPC Cloud Run the-gpl-book service.
   • Home, About
   • Post data
   • Lissajous Graph
   • Mandel, Black & White
   • Surfaces: Sinc, Eggs, Valley, Sq
2. As docker container image.
3. Curls eg: curl https://the-gpl.com/who

Running from Web

You can start a webserver and see simple web-server examples. The command is:

$ the-gpl server -port=8080 # start a web server at port 8080.

Running from CLI

Assuming, the program is installed locally as the-gpl you can access several methods using a CLI. To use autocompletion source the-gpl-autocomplete.sh. Some examples are:

Google API examples

To use the Google Dialogflow Agent and Speech-to-text set up:

1. GOOGLE_APPLICATION_CREDENTIALS shell variable
2. Enable APIs

Here are commands to communicate with the Dialogflow Agent.

$ the-gpl # Prints the help of all modules
$ the-gpl bot -project=gcp-project-id # Will do a short conversation with an agent. 
$ the-gpl bot -project=gcp-project-id -chat=true # Can send messages from stdin
$ the-gpl bot -chat=true -project=gcp-project-id -lang=en-US # Chat with an agent in en-US

To run live-caption speech to text first start a microphone stream on RTP port, and then use the-gpl to listen and apply STT.

$ ffmpeg -f avfoundation -i ":1" -acodec pcm_s16le -ar 48000 -f s16le udp://localhost:9999 # macOS Start microphone streaming
$ the-gpl stt -port=9999 # Will listen to RTP stream on port 9999 for 2 minutes and transcribe in real time

Simple Examples from book

Use these commands to run utilities:

1. bits: That counts number of 1 bits in a Hex input
2. Array examples using mas i.e., maps, arrays and string utilities.
3. Temperature conversions among °F, °K and °C.
4. Measure disk usage in a directory using command du
5. Saving Lissajous gif to a file.

$ the-gpl bits -n=0xBAD0FACE # will count 1 bits in n
$ the-gpl mas -fn=array # Tests array
$ the-gpl mas -fn=comp -n1=123 -n2=345 # Compare n1 and n2

# Temperature utilities
$ the-gpl temp -c=12 -f=12 -k=12 # Converts 12°C to °C/°F/°K
$ the-gpl degrees -c=12°F -f=12°K -k=12°C # Converts 12°C to °C/°F/°K

# du: Disk Usage calculates size of all files in a directory recursively, using go-routines
$ the-gpl du -dir=$HOME/gocode

# Output a Lissajous graph to -file of size 1024 pixels 20 frames and 10 cycles
$ the-gpl lissajous -file ~/Downloads/lis.gif -size=1024 -frames=20 -cycles=10

Crawling Examples

These commands fetch a website and does various operations on it.

# Parse various HTML content of sites URL
$ the-gpl parse -type=outline -site=https://www.airbnb.com # Creates a summary outline of a page
$ the-gpl parse -type=links -site=https://images.google.com #  Prints all links on a webpage
$ the-gpl parse -type=images -site=https://www.yahoo.com # Fetches image URLs in a site
$ the-gpl parse -type=pretty -site=https://www.google.com
$ the-gpl parse -type=crawl -site=https://www.google.com  -dir=/Users/guest/Downloads # Crawl pages to /Users/guest/Downloads/www.google.com 

Simple Servers and Clients

# Server-client 
$ the-gpl service -sp="clock:9999"  # -sp servicePort start clock  service on port 9999
$ the-gpl client  -cp="clock:9999"  # -cp clientPort  start clock  client  on port 9999
$ nc localhost 9999                 # use Mac netcat 'nc' client on port 9999
$ the-gpl service -sp="reverb:9998" # -sp servicePort start reverb service on port 9998
$ the-gpl client  -cp="reverb:9998" # -cp clientPort  start reverb client  on port 9998
$ the-gpl service -sp="chat:9997"   # starts a chat service. Join using:
$ nc localhost 9997                 # Joins chat session as a client

Building from Local Machine

The GPL application can be built using:

1. The plain old go install
2. GCP Cloud run container.
3. As a docker image on docker.com.

See The GPL Docker wiki for docker steps,

Mandelbrot

Here are some sample Mandelbrot fractals created.