lambdaCalc

Code to evaluate lambda expressions.

How to use

Load lambda.hs into GHCi

ghci lambda.hs

To define an expression use the lambda function

lambda "\\x.x"

If you want to store the expression

let e = lambda "(\\x.xx)y"

In the interpreter you must use two '\' since it is an escape character.

\ is used in the place of λ

Variables are one character that aren't '(', ')', '\', '.'

To reduce a lambda expression use reduce.

reduce $ lambda "(\\x.xx)y"

If you want to reduce the expression one reduction at a time (mostly works...) use reduceOne

reduceOne $ lambda "(\\x.\\y.xy)z"

The string parser supports currying. It will allow multiiple parameters and will turn it into nested lambdas.

Reduce does not stop when passed a diverging expression.

reduce $ lambda "(\\x.xx)(\\x.xx)"

will try to reduce forever and will need to be stopped.

The function apply takes 2 strings of lambda expressions and applys the first to the second.

apply "\\x.x" "y"

This produces an expression as output.

The function applyMix applies an expression to a string (to be interpretted as an expression)

let e = lambda "(\\x.x)(\\y.yy)"

applyMix (reduce e) "z"