scalambda

scalambda is a lambda calculus interpreter which allows to choose between different reduction strategies.

It currently supports three different strategies:

• normal-order strategy which choose the leftmost outermost term to reduce
• call-by-name strategy which does not allow reduction inside a lambda abstraction
• call-by-value strategy which only reduces the left part of an application when the right part is a value (that is a term that cannot be further reduced)

scalambda is designed after the presentation of the lambda calculus in "Types and Programming Languages" by Benjamin C. Pierce and is primarily a personal project used as companion to the book. At term it will contain more concepts from the book, such as the possibility to enable typed lambda calculus.

Usage

$ scalambda [file1 [file2 ...]]

Starts scalambda. All the file passed in command line are processed as library files and scalambda will try to load the definition to the environment.

Once scalambda is started, you will get a prompt

λ >

Simply type `:help' to get some help.

You can enter any lambda expression that you want to evaluate under the current strategy like this:

λ > (x.x x) y (λx.x x) y → y y ⇸

The last line indicates that the normal form under this strategy was reached (the default strategy is the call-by-value strategy).

Build

$ git clone git://github.com/gnieh/scalambda.git $ cd scalambda $ ant dist

The project is compiled and a distribution is created in the `dist' directory.