Fails to install happy

[Joe Wood]

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 16.04 LTS
Release: 16.04
Codename: xenial

$ uname -a
Linux vb1 4.4.0-24-generic #43-Ubuntu SMP Wed Jun 8 19:27:37 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

$ ghc -V
The Glorious Glasgow Haskell Compilation System, version 7.10.3

$ cabal -V
cabal-install version 1.22.6.0
using version 1.22.5.0 of the Cabal library

$ cabal install hlint
Resolving dependencies...
Configuring haskell-src-exts-1.17.1...
Failed to install haskell-src-exts-1.17.1
Build log ( /home/joe/.cabal/logs/haskell-src-exts-1.17.1.log ):
Configuring haskell-src-exts-1.17.1...
setup-Simple-Cabal-1.22.5.0-x86_64-linux-ghc-7.10.3: The program 'happy'
version >=1.19 is required but it could not be found.
cabal: Error: some packages failed to install:
haskell-src-exts-1.17.1 failed during the configure step. The exception was:
ExitFailure 1
hlint-1.9.35 depends on haskell-src-exts-1.17.1 which failed to install.

Cant find happy