Detect missing alex and happy in make deps

diff --git a/Makefile b/Makefile
index a29d773995cc7518ae4f141cb213b4724268d6b0..6945d0c5410e10e4327c281c0e296769d471ba69 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -10,6 +10,8 @@ upstream:
        cabal install --user external/ekmett-parsers external/ekmett-trifecta 
 
 deps:
+       alex --version || cabal install alex
+       happy --version || cabal install happy
        cabal install --user --enable-tests --only-dependencies .
 
 build: