Missing examples

In the initial solution template the pattern a (++) b should be a ++ b or (++) a b

Obsolete solutions tab on the profile page doesn't work

I didn't ban any modules.
According to the list of packages posted in the comments to Lensmaker, parsec isn't installed in the test environment, but attoparsec is.

Tests do not check myMinimum on empty Foldable (I assume it should be Nothing)

Real-life NMEA sentences do not contain * in data. I should probably clarify this.

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Isn't it nicer to have balancedParens 0 = [""]?

Haskell tests don't sort anything.

In the paper (http://okmij.org/ftp/tagless-final/JFP.pdf) it is briefly mentioned that it has something to do with coalgebraic structure of λ-calculus with reference to works of F.Honsell and M.Lenisa which consider untyped λ-calculus.

From what I gather:

Set of terms of untyped λ-calculus can be thought as an algebra with operations of λ-abstraction and application. The initial algebra in this setting is the AST and the semantics if a morphism from this initial algebra to some other.

It can also be thought as a coalgebra of a functor F(X) = (T -> X) ∪ {⟂} (here T is the set of terms, each element x in X corresponds to an application function λt.(x t) : T -> X) in some category of sets (they use a weird set theory without foundation axiom, probably to have models of λ-calculus in it). The final coalgebra is a model of λ-calculus and the semantics is given by specifying a "real function" to each term

I'm not sure how all this can be properly done in types.

Fixed