articles/smalltalk.md: add syntax postcard example

articles/smalltalk.md

@@ -28,6 +28,28 @@ being able to contain the code of a program and its live state (similar to how s
 - Smalltalk-80: most popular standard
 - ANSI Smalltalk: released in 1998
 
+## Smalltalk minimal syntax demostration
+Unknown author.
+```smalltalk
+exampleWithNumber: x
+
+"A method that illustrates every part of Smalltalk method syntax
+except primitives. It has unary, binary, and keyword messages,
+declares arguments and temporaries, accesses a global variable
+(but not and instance variable), uses literals (array, character,
+symbol, string, integer, float), uses the pseudo variables
+true false, nil, self, and super, and has sequence, assignment,
+return and cascade. It has both zero argument and one argument blocks."	
+
+    |y|
+    true & false not & (nil isNil) ifFalse: [self halt].
+    y := self size + super size.
+    #($a #a "a" 1 1.0)
+        do: [:each | Transcript show: (each class name);
+                                 show: ' '].
+    ^ x < y
+```
+
 ## Implementations
 - [Squeak](https://squeak.org/)
 - [Pharo](https://pharo.org/): fork of Squeak