Untyped λ-calculus interpreter

Expressions E:

• λ-abstraction: ^ x y .. z . E
• λ-abstraction: \ x y .. z . E
• abstraction: E₁ E₂

Commands:

• E – evaluate expression E
• x := E – define x
• :constant x – declare constant x
• :context – print current context
• :lazy – lazy evaluation
• :eager – eager evaluation
• :deep – evaluate inside λ-abstractions
• :shallow – only evaluate top level

In a file commands must be separated with ;.