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Open Source Day: learning Smalltalk
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osd-8-2017-08-28.md

OSD #8

TL;DR: Learning Smalltalk

Objective

  1. Run Pharo http://pharo.org/
  2. Use Moose http://www.moosetechnology.org/
  3. Try SmaCC https://github.com/ThierryGoubier/SmaCC

Main sources:

Learning Smalltalk

Screenshot of running Pharo VM

Good resources:

0. Installing & Launching Pharo VM

brew cask install pharo-launcher
# Chose Moose 6.0
# follow http://themoosebook.org/book/index.html#h1mooseinanutshell
Pharo6.0.app/Contents/MacOS/Pharo Pharo6.0.app/Contents/Resources/Pharo6.1.image

I. Simple Smalltalk program

World (click) -> Playground

ProfStef go. (cmd+d to evaulate, using "Do It")

a := OrderedCollection new
  add: 1;
  add: 2;
  add: 3;
  yourself.

a. (cmd+p to print)

Number extend [
  my_factorial [
    (self < 2) ifTrue: [ ^1 ]
               ifFalse: [ |c|
                 c := OrderedCollection new.
                 2 to: self do: [ :i | c add: i ].
                 ^ (c fold: [ :a :b | a * b ] ) ]]].

7 factorial.
7 my_factorial.


a := OrderedCollection new
  add: 1;
  add: 2;
  add: 3.

Transcript show: a.

Built-in tools and commands:

  • Playground/workspace: "Do it", "Print it", "Insepct it"
  • Transcript as console.log or System.out
  • System Browser message or cmd+b
  • Spotter - just Shift+Enter
    • #class
    • #implementor

II. Code visualization using Moose

Steps:

  • Extract the data, build model

    wget .../jdt2famix-bin-1.0.3.zip
unzip jdt2famix-bin-1.0.3.zip
git clone --depth 1 git@github.com:rastaman/argouml-maven.git
cd argouml-maven
mvn dependency:copy-dependencies -DoutputDirectory=dependencies -DoverWriteSnapshots=true -DoverWriteReleases=false
../jdt2famix-1.0.3/jdt2famix.sh

  • Open Moose: World (click anywhere) -> Moose

  • Load the model: MSE (right corner) -> coose "argouml-maven.mse"

  • Select just loaded "argouml-maven" model

  • Select "All methods"

  • Visualize all/@Deprecated methods

    view := RTMondrian new.

view shape circle
	if: [ :each | each isAnnotatedWith: 'Deprecated' ]
	color: Color red.
	
dep := (self, ( self flatCollect: #clientTypes ) ) asSet.

view nodes: dep.
view layout grid.
view

Screenshot of code visualization using Moose

Further reading:

III. Simple parser using SmaCC

  • World (click anywhere) -> Tools -> SmartCC Parser Generator

  • Simple grammar

    <number> : [0-9]+; 
<whitespace> : \s+;

Expression 
	: Expression "+" Number
	| Number
	;
Number 
	: <number>
	;

  • add Scanner/parser names

    • Options -> Scanner Class
    • Options -> Parser Class

  • File -> Save

  • Test tab

    3 + 4
    • Validate: (Select text) -> Evaluate
    • Inspect AST: (Select text) -> Inspect

IV. Add Smalltalk to exercism.io

http://exercism.io/ is awesome, but lacks any Smalltalks for now.

Apps

Articles

Learnings

 + image-based approach to programming (Docker/VirtualBox)
 + everything is an _object_ (blocks, control structures, etc) that sends _messages_
 + Less is more: No type declarations, no primitive objects,
    no generic types, no modifiers, no operators, no inner classes,
    no constructors, and no static methods
 + Awesome tooling: System Browser, Spotter
 + at least single VM tree: https://github.com/OpenSmalltalk/opensmalltalk-vm
 + Existing grammars in SmaCC: JS, Java, C/C#, etc

 - fragmentation of the world: VisualWorks, Dolphine, Squeak, Pharo, GemTalk,  ... 
 - external Pharo-launcher to manage VMs/Images that the OS app loads
 - no propper default keybidings support for editors :/
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