persistent-refs-0.1: dependencies

Dependencies for persistent-refs-0.1

library	base (>=4.0 && <5) containers (>=0.4 && <0.6) lens (>=3.7 && <3.9) mtl (>=2.1 && <2.2) ref-fd (>=0.3 && <0.4) transformers (>=0.3 && <0.4)