Lamb

lamb is an implementation of the pure untyped lambda calculus in modern, safe Rust.

Installation

• Library

  Add lamb as a dependency in Cargo.toml:

  [dependencies]
  
  lamb = "0.1.0"
  
  

  The Cargo features repl and prelude can also be enabled to interface with the REPL and prelude:

  [dependencies]
  
  lamb = { version = "0.1.0", features = ["repl", "prelude"] }
  
  

• Binary

  Install lamb through Cargo:

  cargo install lamb
  

Features

• Library

  Default:

  • Construct terms programmatically
  • β-reduce terms using different reduction strategies
  • Implement custom β-reduction strategies

  With prelude enabled:

  • Use pre-defined terms from the prelude

  With repl enabled:

  • Parse terms from strings
  • Construct REPLs programmatically and execute commands

• Binary

  • β-reduce terms using any pre-defined β-reduction strategy:

    λ> (λx. x) (w z)
    Info: Reduced 1 times
    w z
    λ>
    

  • Bind terms to names to automatically substitute in future free variables:

    λ> id = λx. x; const = λx y. y;
    Info: Binding id added
    Info: Binding const added
    λ>
    

  • Display or change the β-reduction limit:

    λ> :limit 1024
    Info: Reduction limit set to 1024
    λ> :limit
    Info: Current reduction limit is 1024
    λ>
    

  • Exit gracefully:

    λ> :exit