Inform 7
Inform 7 is a natural language based programming language for Interactive Fiction.
Factoid
Inform 7 is among the easiest languages to read, and was surreptitiously featured in why the lucky stiff's printer spool book. His code and the game it compiles to can be played online.
Length 3
X:Y
Inform 7 is a rules based language. The standard library defines many rulebooks and the player can define more. These rules are used for event handling and to create extensible procedures. Each rulebook can contain several rules, which consist of a rule preamble, and a body. The rule preamble is at a minimum the name of the rulebook, but it can also have many additional conditions.
In this example the rulebook preamble is the name of the rulebook X, and the body consists of a single phrase (function) Y. Inform 7 code is usually much more verbose than this, so these short examples will not be able to showcase the natural language aspects of the language ;).
Length 4
X YY
Each rulebook has a name and a basis: a variable type which is the main parameter for the rulebook. When you call a rulebook you can optionally call it for a particular value, which must match the type of the basis.
When a rulebook is called it goes through the rules in order and runs whichever rules have matching preambles. The preambles can specify that they want to run only for a particular subclass of the basis, only for values which meet a specific condition, or only for a single specific value. Rulebooks normally run all the rules with a matching preamble, but rules can stop it from continuing. The rules of a rulebook are automatically sorted in order from most to least specific so that if only one rule will be run, it will be the most specific one (though rules can be manually repositioned).
This example specifies a rule preamble for the rulebook X. YY could be either a subclass of the basis, an adjective phrase which checks whether the value matches some condition, or a particular object called YY.
Length 5
"[s]"
Here's the first example of real code! Text in Inform 7 can either be a simple literal string, or a dynamic text with substitutions which are processed at run time. Under the hood these texts are compiled to functions, but they are entirely interchangeable with simple literals.
Text substitutions can run essentially any other phrases/functions, and can be passed arguments too. Many come predefined in the base library. This example, the to say s phrase, will print an 's' if the last number printed was not 1. Similar substitutions can be used for entire sentences to output the correct grammatical inflections for a particular narration style (such as first person past tense or third person future tense), even allowing the narration style to be changed at run time.