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+# What is this project?
+
+This project contains a compiler and runtime environment to calculate
+simple arithmetic expressions (simple as in only `+-*/`).  
+The compiler is written in Haskell and the the runtimesystem
+is written in C.
+
+# How does it work?
+
+The compiler restructures the arithmetic expression into an abstract
+syntax tree.
+The nodes of this tree contain the operation and the leafes are the
+constants of the expression.
+The syntax tree is then traversed in order to transform the expression
+into Reverse Polish Notation ([RPN](https://en.wikipedia.org/wiki/Reverse_Polish_notation))
+and building the commands to calculate the results on a [stack machine](https://en.wikipedia.org/wiki/Stack_machine).
+The assembler then translates the commands into a bytestring an saves the result an a file.
+The runtime system reads the bytestring reconstructing the
+commands and executes them using an operand stack.
+This design is heavily influence by the [Java Virtual Machine](https://en.wikipedia.org/wiki/Java_virtual_machine), but providing not nearly as much features.
+
+# But why?!
+
+Mainly for the fun and learning.
+I need to learn Haskell for University so I figuered I try to
+write the compiler and assembler in it.
+However I also always wanted to write something more than a "Hello world!"
+in C and figured a stack machine would be the perfect fit, as it isn't too
+complex but also more than the simple "Hello world!".