Programming with Dependent Types

Getting Started

Prerequisites

• Haskell Platform
• Emacs
• git

Installing Agda

• cabal update
• cabal install Agda
• agda-mode setup

Getting the libraries

• git clone https://github.com/UlfNorell/agda-prelude
• git clone https://github.com/UlfNorell/agda-summer-school
• cd agda-prelude/agda-ffi
• cabal install

Set up Emacs paths

• M-x agda2-mode
• M-x customize-group agda2
• Add the absolute path to agda-prelude/src to Include Dirs (do not remove "." from the list)

Check that it works

• Open agda-summer-school/exercises/Lambda.agda in Emacs
• Hit C-c C-l to type check
• Hit C-c C-x C-c to compile
• You should now have an executable Lambda in exercises/
• Run ./Lambda example.lam. This should print a desugared lambda term and the result of running it through the SECD machine.

Exercises

Resources

• Agda Wiki
• Mailing list
• IRC channel #agda on freenode
• doc/AgdaCheatSheet.agda contains a number of small examples showing some of the features of Agda.
• doc/EmacsCheatSheet.html lists the most commonly used Emacs mode commands.
• Browse the library. Use M-. or middle mouse to jump to the definitions of library functions.

Day 1

• exercises/Lists.agda
• Bonus: exercises/Grep.agda

Day 2

• exercises/Term.agda
• exercises/Term/Eval.agda
• exercises/TypeCheck.agda

Day 3

• Copy exercises/SECD/Unchecked.agda to exercises/SECD/StackSafe.agda and add types to ensure stack safety.
• Copy your stack safe SECD machine to exercises/SECD/TypeSafe.agda and add type safety (running well-typed terms).
• Change the compiler in exercises/SECD/Compiled.agda to compile well-typed terms and adapt your type safe SECD machine to run the compiled terms.
• Bonus (hard): Track semantics in the types. In the end you should have a run function that is guaranteed to compute a value corresponding to eval t for an input term t.

Day 4

• Add more features to the lambda calculus (natrec, booleans, ...).
• Invent your own exercises.

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Git commands for keeping fork up-to-date with upstream repo

git remote add upstream [email protected]:UlfNorell/agda-summer-school.git
git fetch upstream
git merge upstream/OPLSS
git push origin OPLSS