Functions inside readers: there must be a better way. And, lenses start becoming useful!

Playing with indexed lenses, and binary search

Modular arithmetic and off-by-one.

Taking too long, and parallelism not working.

It's all about the sets

Laziness makes cycle finding easy to express

A*, beam search, and typeclasses

Data is code; code is data

Finding the right representation

Implementing the Ord typeclass

The return of A* search

Return of the RWS monad!

Plenty of scope for off-by-one errors

List munging and folding

Ah, tails.

Interval relations FTW

Overengineering for a part 2 that didn't come

Parse, don't validate

Easing back into it.

A few observations about completing the challenges.

Unfolding a simulation

Nondeterminism, list monads, and dodgy heuristics