The form bakery 
is an educational tool for Laws of Form. It renders Laws of Form expressions like `<a>b` into truth tables. Note that the re-entry discussed in chapter 11 of Laws of Form is not discussed in the form bakery. The form bakery has been inspired by George Burnett-Stuart's work .
The form bakery is implemented with Functional Reactive Programming.
The algebraic data type representing Laws of Form expressions is slightly too big.
data Expr = Cross Expr | Call [Expr] | Var Char