Introduction to programming language theory in Agda
Switch branches/tags
Nothing to show
Clone or download

layout title permalink

Build Status

How to build the book

There are several tools you need to build a local copy of the book:

For most of the tools, you can simply follow their respective build instructions. We aim to maintain compatibility with the latest release of Agda and the standard library. Most recent versions of Ruby should work.

We advise installing agda2html using Stack:

git clone
cd agda2html
stack install 

Once you have installed these tools, you can build the book from source:

make build

You can host your copy of the book locally by running

make serve

The Makefile offers more than just these options:

make                      (builds lagda->markdown)
make build                (builds lagda->markdown and the website)
make build-incremental    (builds lagda->markdown and website incrementally)
make test                 (checks all links are valid)
make serve                (starts the server)
make server-start         (starts the server in detached mode)
make server-stop          (stops the server, uses pkill)
make clean                (removes all ~unnecessary~ generated files)
make clobber              (removes all generated files)

If you simply wish to have a local copy of the book, e.g. for offline reading, but don't care about editing and rebuilding the book, you can grab a copy of the master branch, which is automatically built using Travis. You will still need Ruby and Bundler to host the book (see above). To host the book this way, download a copy of the master branch, unzip, and from within the directory run

bundle install
bundle exec jekyll serve

GNU sed and macOS

The version of sed that ships with macOS is not fully compatible with the GNU sed. Therefore, you may get errors such as:

sed: 1: "out/plfa/": invalid command code o

You can fix this error by installing a GNU compatible version of sed, e.g. using Homebrew:

brew install gnu-sed --with-default-names

Updates to agda2html

Sometimes we have to update agda2html. To update your local copy, run the following commands from your clone of the agda2html repository, or simply follow the installation instructions again:

git pull
stack install

Unicode characters

If you're having trouble typing the Unicode characters into Emacs, the end of each chapter should provide a list of the unicode characters introduced in that chapter. For a full list of supported characters, see agda-input.el.

Using agda-mode

?            create hole
{!...!}      create hole
C-c C-l      load buffer

Command to give when in a hole:

C-c C-c x    split on variable x
C-c C-space  fill in hole
C-c C-r      refine with constructor
C-c C-a      automatically fill in hole
C-c C-,      Goal type and context
C-c C-.      Goal type, context, and inferred type

See the emacs-mode docs for more details.

If you want to see messages beside rather than below your Agda code, you can do the following:

  • Load your Agda file and do C-c C-l;
  • type C-x 1 to get only your Agda file showing;
  • type C-x 3 to split the window horizontally;
  • move your cursor to the right-hand half of your frame;
  • type C-x b and switch to the buffer called "Agda information"

Now, error messages from Agda will appear next to your file, rather than squished beneath it.


The book is written in Kramdown Markdown.


Clone this repository with

git clone

Travis Continuous Integration

Travis offers continuous integration, and automatically updates the website. View the build history and error messages at