The standard library aims to contain all the tools needed to easily write both programs and proofs. While we always try and write efficient code, we prioritise ease of proof over type-checking and normalisation performance. If computational performance is important to you, then perhaps try agda-prelude instead. You can browse the library source code in glorious clickable html here.
Use version v0.15 of the standard library with Agda 2.5.3.
Install it as follows. Say you are in directory $HERE (replace appropriately).
git clone https://github.com/agda/agda-stdlib.git
cd agda-stdlib
git checkout v0.15
cabal install
The last comment is optional, omit it if you are lacking cabal.
Register it by adding the following line to $HOME/.agda/libraries:
$HERE/agda-stdlib/standard-library.agda-lib
To use the standard library in you project $PROJECT, put a file
$PROJECT.agda-lib file in the project root containing:
depend: standard-library
include: $DIRS
where $DIRS is a list of directories where Agda
searches for modules, for instance . (just the project root).
If you want to refer to the standard library in all your
projects, add the following line to $HOME/.agda/defaults
standard-library
Find the full story at readthedocs.
If you would like to suggest improvements, feel free to use the Issues tab.
If you would like to make improvements yourself, follow the instructions in
HACKING.
If you're using an old version of Agda, you can download the corresponding version of the standard library on the Agda wiki.
If you're using a development version of Agda rather than the latest official release
you should use the experimental branch of the standard library rather than master.
The experimental branch contains non-backwards compatible patches for upcoming
changes to the language.