Free Monad Generation Skill (PLUS +1)

Free structure generation from signatures

Trit: +1 (PLUS)
Color: #D82626 (Red)
Role: Generator/Creator

Core Concept

Free monads generate structure from a functor signature:

data Free f a 
  = Pure a                    -- Leaf (return)
  | Roll (f (Free f a))       -- Node (bind)

Universal property: Free f is left adjoint to forgetful functor U.