Update README.md

README.md

@@ -4,10 +4,7 @@ Extensible HAHA transpiler.
 ![Logo](assets/logo.svg)
 
 ## Overview
-Humouresque is a transpiler/code extraction utility to turn HAHA proofs into programs. Any function written using the [Hoare Advanced Homework Assistant (HAHA)](http://haha.mimuw.edu.pl/) can be converted into a function in any of the supported target languages. Currently only Java is suppported as a transpilation target. A few things to note:
-+ The transpiler project and [parser project](https://github.com/lambdacasserole/haha-parser/) are separate, though this one depends on that one.
-+ This project uses precisely *none* of the original HAHA source code. It may therefore be the case that code that works just fine in HAHA causes the parser to choke. This can usually be worked around with minor syntax tweaks.
-+ This project is not formally verified, nor does it generate/discharge any verification conditions. Hoare logic annotations are completely ignored, except to be erased during transpilation (actually, they're converted to comments, but same thing).
+Humouresque is a transpiler/code extraction utility to turn HAHA proofs into programs. Any function written using the [Hoare Advanced Homework Assistant (HAHA)](http://haha.mimuw.edu.pl/) can be converted into a function in any of the supported target languages. Currently only Java is suppported as a transpilation target. The transpiler project and [parser project](https://github.com/lambdacasserole/haha-parser/) are separate, though this one depends on that one.
 
 ## Building
 This is a [Maven](https://maven.apache.org/) project and can be built like one. To generate classes:
@@ -60,9 +57,79 @@ The options are quite straightforward:
 | Option        | Values              | Required? | Description                                                               |
 |---------------|---------------------|-----------|---------------------------------------------------------------------------|
 | input_file    | Any                 | Yes       | The HAHA source file to transpile.                                        |
-| `-e`          | None                | No        | Enumeration mode. Prints out the names of all functions in the file.       |
+| `-e`          | None                | No        | Enumeration mode. Prints out the names of all functions in the file.      |
 | `-f`          | `fname1,fname2,...` | No        | Transpile only specific functions with names in the comma-delimited list. |
 | `-a`          | `fname`             | No        | Arity mode. Gets the number of arguments taken by the specified function. |
 | `-t`          | Target language     | No        | Specify target language. Defaults to Java. Only Java currently supported. |
 
 Results are written to standard output.
+
+### Example
+As an example, consider the following HAHA source file `sum.haha` that performs addition of two numbers:
+
+```pascal
+function sum (x : Z, y : Z) : Z
+precondition y >= 0
+postcondition sum = x + y
+var ans : Z
+    n : Z
+begin
+	ans := x
+	{ y >= 0 /\ ans = x }
+	n := y
+	{ y >= 0 /\ n >= 0 /\ ans = x /\ n = y }
+	while n != 0 do
+	invariant y >= 0 /\ n >= 0 /\ ans + n = x + y 
+	begin
+		ans := ans + 1
+		{ y >= 0 /\ n > 0 /\ ans + n - 1 = x + y } 
+		n := n - 1
+		{ y >= 0 /\ n >= 0 /\ ans + n = x + y }
+		skip
+	end
+	{ n = 0 /\ ans + n = x + y }
+	sum := ans
+end
+```
+
+Running Humoresque with `java -jar humoresque.jar sum.haha`, we get the following output:
+
+```java
+int sum(int x, int y)
+{
+	int ans;
+	int n;
+	int sum;
+	ans = x;
+	/* y >= 0 /\ ans = x */
+	n = y;
+	/* y >= 0 /\ n >= 0 /\ ans = x /\ n = y */
+	while(n != 0)
+	{
+		ans = ans + 1;
+		/* y >= 0 /\ n > 0 /\ ans + n - 1 = x + y */
+		n = n - 1;
+		/* y >= 0 /\ n >= 0 /\ ans + n = x + y */
+	}
+	/* n = 0 /\ ans + n = x + y */
+	sum = ans;
+	return sum;
+}
+```
+
+As you can see, all proof-related stuff is erased, aside from annotations which are preserved as comments.
+
+## Limitations
+This tool is currently subject to the same limitations as [the parser it's built on](https://github.com/lambdacasserole/haha-parser/), plus a few others:
+* This project uses precisely *none* of the original HAHA source code. It may therefore be the case that code that works just fine in HAHA causes the parser to choke. This can usually be worked around with minor syntax tweaks.
+* This project is not formally verified, nor does it generate/discharge any verification conditions. Hoare logic annotations are completely ignored, except to be erased during transpilation (actually, they're converted to comments, but same thing).
+
+## Contributing
+For most intents and purposes, this project is considered to fulfil its original use case. Bug fixes and suggestions are welcome, however, from any member of the community.
+
+## Acknowledgements
+A big thank you to the team at the [University of Warsaw](https://mimuw.edu.pl/en) behind [HAHA](http://haha.mimuw.edu.pl/). This really is an awesome tool for teaching software verification! By name, they're:
+* [Tadeusz Sznuk](http://www.mimuw.edu.pl/~tsznuk/)
+* Jacek Chrząszcz
+* [Aleksy Schubert](http://www.mimuw.edu.pl/~alx/)
+* Jakub Zakrzewski