hack to fix building on ghc-7.8.1-rc2 (closes #402 and #403)
hack to fix building on ghc-7.8.1-rc2 (closes #402 and #403)

hvr/lens,Icelandjack/lens,cchalmers/lens,danidiaz/lens,Gabriel439/lens,cdepillabout/lens,hvr/lens,rpglover64/lens,ddssff/lens,timjb/lens,Fuuzetsu/lens,omefire/lens