lfp-tictactoe
For London (Canada) Functional Programmers: my notes on Chris Penner's blog post Type Tac Toe: Advanced Type Safety.
Direct from Chris Penner's post:
- BasicLib.hs: no type safety
- Alternating.hs: types enforce alternating turns
- PreviousMoves.hs: types enforce alternating turns and taken board positions
Additional stuff by me:
- TypeLevel.hs: Lift entire game board to the type level and show how to display it
- Consolidated.hs: Consolidate "play" functions into single function that can statically enforce alternating turns and prevent replays. Entire board is represented at the type level. Doesn't support enforcing the invariants with runtime input.
- Lib.hs: Show exactly where we need dependent (pi-)types for the first time to enforce the invariants with runtime (term-level) input.
To use this repo, first install the Haskell Tool Stack.