chi questions

chi answers

• How does mzero match guard type signature?
• Defining fmap with id and return
• What is the difference between :~: and :~~: equalities?
• Writing Category Instance for custom Lens
• why it was infinite type ? (Occurs check: cannot construct the infinite type: a ~ Tree a)
• Deriving a base monad using a monad transformer and the identity monad
• How to filter all multiples of a certain number out of a list in Haskell using filter
• Create my own state monad transformer module hiding underlying state monad
• H-99 Problems: #26 Can't Understand The Solution
• Combine results within a monad without do