A hacky lambda calculus interpreter
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HackyLambdas is the final project for Lambda Calculus by Ian Wold and Paul Yon.

I used the Sprache parser to parse the lambda terms. The lambda calculus is very left-recursive, so I got around this by using Sprache's operator capabilities to parse the functions and applications - viewing the period and the space as operators allows one to hackily get around the left recursion in the grammar. Surely there's a better way, but this is the fun way.

Using it

HackyLambdas can do several things. First, it can beta-reduce and compute typing constraints for simply typed lambda calculus terms. In place of a lambda, a backslash is used. For example, one could input the following:

>: (\x.x) y

And HackyLambdas will beta-reduce it, as well as compute the typing constraints on the term.

You can define terms with HackyLambdas:

>: true = \a.\b.a

You can type in integers, and they will be translated into Church-encoded numerals automagically:

>: 5

HackyLambdas can convert any LC term to its corresponding DeBruijn notation:

>: debruijn
db>: \x.x

And HackyLambdas can check for alpha-equivalence between any two terms

>: alpha
a1>: \x.x
a2>: \y.y