Add build instructions

Thanks to Jesse Selover <jselover@google.com> for trying them out.

1 files changed, 26 insertions, 0 deletions

diff --git a/README.md b/README.md
index 479da5a..fd46043 100644
--- a/README.md
+++ b/README.md
@@ -12,6 +12,32 @@ Policy](https://pvp.haskell.org), and we will not post btls on Hackage.
 **btls is not production ready yet.** It is feature-incomplete and has not
 undergone review or auditing.
 
+## Building
+
+btls includes a copy of BoringSSL as a Git submodule. Ensure you’ve checked out
+that submodule before building. If you’ve just cloned btls, `git submodule
+update --init` should do it. You’ll also need all of BoringSSL’s build
+dependencies. On Debian, run
+
+    apt install cmake gcc g++ golang ninja-build perl
+
+to install them. You do not need to build BoringSSL itself; btls’s Setup.hs will
+take care of that for you.
+
+btls needs GHC, c2hs and a few Haskell libraries to build. On Debian,
+
+    apt install c2hs ghc libghc-gtk2hs-buildtools-dev
+
+should get you everything you need; you can also run
+
+    apt install libghc-{base-compat,base16-bytestring,smallcheck,tasty,tasty-hunit,tasty-smallcheck}-dev
+
+if you want to install everything you can through APT instead of Cabal. Once
+you’ve done so, you can build and run the test suite.
+
+    cabal new-build tests
+    dist-newstyle/build/btls-*/build/tests/tests
+
 ---
 
 This is not an official Google product.