From 1cf8c29c2d8e5bafe45f134d26f916d61267ec13 Mon Sep 17 00:00:00 2001
From: tocariimaa <tocariimaa@firemail.cc>
Date: Sat, 8 Mar 2025 15:37:23 -0300
Subject: [PATCH] articles/smalltalk.md: more information, code examples

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 1 file changed, 48 insertions(+), 4 deletions(-)

diff --git a/articles/smalltalk.md b/articles/smalltalk.md
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 # Smalltalk
-Smalltalk is a pure [object oriented](oop.md) (not the "modern" variant) and highly dynamic programming language created in Xerox PARC
-by a group of scientists, including Alan Kay. Smalltalk builds upon a minimal set of primitive objects.
+Smalltalk is a pure [object oriented](oop.md) (not the "modern" variant), [garbage collected](garbage_collection.md)
+and highly dynamic [programming language](programming_language.md) created in Xerox PARC by a group of scientists, including Alan Kay.
+Smalltalk has a [minimal](minimalism.md) [syntax](syntax.md) which is famously said to be able to "fit on a postcard";
+building upon a minimal set of primitive objects.
+
+Smalltalk is built upon the concept of message passing, where objects communicate between each other by sending messages, which
+can optionally carry a value. Unlike most OOP languages, an object can receive any message and its up to it whether to reply it
+or return an error if it doesn't understand the received message.
+
+```smalltalk
+"Sends the message `say` to `anObject` with the value `hi`"
+anObject say: 'hi'
+```
 
 Being a highly dynamic language, Smalltalk is usually used in an [IDE](ide.md) supporting this paradigm by using
 [GUI](gui.md) to allow for easier inspection of the program, but "headless" implementations of Smalltalk exist.
 
+In Smalltalk implementations that provide with an interactive environment, Smalltalk code is not saved exactly
+in a textual form like other programming languages; instead Smalltalk is more "image" oriented, with an image
+being able to contain the code of a program and its live state (similar to how some [Lisps](lisp.md) work).
+
 TODO
 
 ## Implementations
 - [Squeak](https://squeak.org/)
-- [Pharo](https://pharo.org/)
+- [Pharo](https://pharo.org/): fork of Squeak
 - [GNU Smalltalk](https://www.gnu.org/software/smalltalk/): headless implementation
 - ...
 
 ## Examples
+For now the examples that I will show here are run in GNU Smalltalk to keep things textual. GNU Smalltalk uses
+the `.st` extension for Smalltalk files.
+
+### Hello world
+Here we send a string to the global `Transcript` object, which will output
+the message in the "transcript" window (on a GUI environment) or to stdout for a headless implementation (like GNU Smalltalk).
+```smalltalk
+Transcript show: 'Hello, world!'; cr.
+```
+and run it with:
+```sh
+gst hello.st
+```
+
+### Extending a class: `String`
+We can also extend builtin classes such as `String` to add our own method:
+```smalltalk
+'smalltalk' removeVowels.       "Error: `String` doesn't understand this message"
+String extend [
+    removeVowels [
+        ^(self reject: [:c | c isVowel])
+    ]
+]
+'smalltalk' removeVowels.       "==> smlltlk"
+```
+
 TODO
 
 ## Resources
+- <https://learnxinyminutes.com/smalltalk>
+- [Smalltalk Cheatsheet](https://angelfire.com/tx4/cus/notes/smalltalk.html)
+- [GNU Smalltalk User's Guide](https://www.gnu.org/software/smalltalk/manual/)
 - [*The Cuneiform Tablets of 2015*](https://tinlizzie.org/VPRIPapers/tr2015004_cuneiform.pdf):
-paper describing how an Smalltalk-72 interpreter could be engraved in a rock.
+paper describing how an Smalltalk-72 interpreter could be engraved in a rock for reliable future-proof preservation.