The following shows that the latest nixos-unstable channel has all the transitive dependencies for
haskellPackages.lens available for fetching from the binary cache:
$ nix-env -f https://releases.nixos.org/nixos/unstable/nixos-18.09pre149415.8395f9aa85e/nixexprs.tar.xz \
-iA haskellPackages.lens --dry-run
(dry run; not doing anything)
installing 'lens-4.16.1'
these paths will be fetched (136.28 MiB download, 1899.17 MiB unpacked):
/nix/store/1igraczgfcnik4dcm7qdhw71ww7cipqg-semigroupoids-5.2.2-doc
/nix/store/1mclh2v2w8wq5bnk9sg4svrrcskpa5l6-lens-4.16.1-doc
/nix/store/2bfj10yf31z3s5ga61pyqdhnmqx8q888-exceptions-0.10.0-doc
/nix/store/2r3pa71z7g56bx65dqs93w3285xx9cn4-bifunctors-5.5.3
/nix/store/2vxhd8x1lq85jjkhjahh7inqrg0iv6qf-comonad-5.0.4
/nix/store/2zh7xsl3wg37ysj0zc6xc8ywz5rjvgpc-gmp-6.1.2-dev
/nix/store/36gb9s8vl3vfmq531g732l49l8cd93m6-transformers-base-0.4.5.2
/nix/store/3fq70grvdwdzrxg4jb077nqf6yl99lwd-profunctors-5.2.2-doc
/nix/store/4ai2f6sv82r82khjmczbimzk6d339xv3-semigroupoids-5.2.2
/nix/store/4bjjiqi5yj6b7agfbngwp68kb3f17v15-semigroups-0.18.5
/nix/store/507h0v7ngmzqc018jm0r2bswx8ji4ly9-hashable-1.2.7.0-doc
/nix/store/50skf9rlag69wswzl7f92abiqrj88v8s-transformers-compat-0.6.2
/nix/store/54fg70ffinghp2s1dyxjjz9cwp5zdz22-transformers-base-0.4.5.2-doc
/nix/store/71rspnn0lg7cgkigywwkp414s0ivysb4-unordered-containers-0.2.9.0-doc
/nix/store/7jgd2ih28l6354ckpsj20wwf33zy73zh-th-abstraction-0.2.8.0-doc
/nix/store/7pq7x9dzx2jcc206v33fpiv2sbyfg7ng-lens-4.16.1
/nix/store/90nsh4qr5j474wg2kb8hirnygqbifjld-invariant-0.5.1-doc
/nix/store/9jz97ylpxy57f41146i9hwn27368crzc-kan-extensions-5.2
/nix/store/9wj46jfahzddy0nkrzczsp819h0p7cis-bifunctors-5.5.3-doc
/nix/store/a0dr5x063v0zm8z0z5fwh8dldg10yl07-ghc-8.4.3
/nix/store/af8bmnbh3h20p9r3alazqh6a7p0r42qn-parallel-3.2.2.0
/nix/store/ar8v6nhym950bagk8n5ldj6mmhwwkkqf-distributive-0.5.3-doc
/nix/store/bqwhqa4z8z0n3jr9z0b4815kpyjmkkf4-StateVar-1.1.1.0
/nix/store/c9cvv73vilsba21xzi50sjs5kqz8b1qi-adjunctions-4.4
/nix/store/chww0b0ygyq9a84dwg20m2yil2s5lhij-base-orphans-0.7
/nix/store/d60s5bwv6r3hl6w8cg5j7znwaiva43n8-gmp-6.1.2
/nix/store/dz284sqnfsjl1ivqfmx5glby7fxdywm2-transformers-compat-0.6.2-doc
/nix/store/fbzjfsy1havxhc4xizfb395diphp18r9-hashable-1.2.7.0
/nix/store/fsmfcnimyyab5rhgksd02vhb6bwbn55m-adjunctions-4.4-doc
/nix/store/fz4lx66fjvi9dsv5qlfa07l48yc5hf20-distributive-0.5.3
/nix/store/gj2iik3wp816mqfbr1smyzx4nx2fcplh-contravariant-1.4.1
/nix/store/j2gb71m4mhdn625b92d324x3029vri0x-invariant-0.5.1
/nix/store/j3shm1pf1g3j1zn2gfrv1mk7vizznprh-StateVar-1.1.1.0-doc
/nix/store/j4vspd7kxv0gwn0j45gd2mr1hwzzq6b6-semigroups-0.18.5-doc
/nix/store/js55b2a94998sncw760wgn38rz7s5w20-th-abstraction-0.2.8.0
/nix/store/kf5ysi2wyjfy9c0bkmr3wpxkl49iyinw-call-stack-0.1.0
/nix/store/kwmzq0jnb9wf262l6r5yqaqv72ai8i59-base-orphans-0.7-doc
/nix/store/l4ayxz2m8yjd94syc1j406402prphfbg-call-stack-0.1.0-doc
/nix/store/mbcw4nvn2ql74k2bgkvcq84g0fabqrpn-free-5.0.2-doc
/nix/store/nhs0k30m69zlyfmdymf656n0ni6g2glh-comonad-5.0.4-doc
/nix/store/phb98bj6ypk5zrdpif55bnkdy9jzyz7j-tagged-0.8.5-doc
/nix/store/q8713z03bs42qg2isw93g812rwwg7g61-exceptions-0.10.0
/nix/store/qk8dr1ip0jgv7ld53x9qp6ggs8k82c1k-ghc-8.4.3-doc
/nix/store/qw4ns0ji3mys59h57g0cg7rgg9wvfmq9-reflection-2.1.4
/nix/store/qy80cinypwmj2xj0s7irk01dxb82zdn8-kan-extensions-5.2-doc
/nix/store/r86s8rqb1qqc7hprx4m6ckhbhckvw30a-contravariant-1.4.1-doc
/nix/store/rpgjrjiv5kkan2fpml6zhnnwwaqyl76p-primitive-0.6.3.0-doc
/nix/store/rvrclbll4kx2ysqy7zrl1081qzp5hr0w-reflection-2.1.4-doc
/nix/store/sxaxgw56lnh7rrr4i9h5wz74lp4xwqyp-free-5.0.2
/nix/store/wbml90xhcwc0n2xq2cgjph99m53x2nc8-vector-0.12.0.1-doc
/nix/store/wczc2zffwlp62db9bz5xbd7ca4il8mrz-vector-0.12.0.1
/nix/store/wlw8bqfh1xv07yg78b7lnlzla165prpn-void-0.7.2
/nix/store/x4x3943a149aw7q426yyzc9v7i3cpnfh-profunctors-5.2.2
/nix/store/z039zfi4b3kzzqrqgkavy7hxgsvq3spd-primitive-0.6.3.0
/nix/store/z3vq0dcd01qfqh395dyx5jzf3cailwds-parallel-3.2.2.0-doc
/nix/store/z55mif177b49wwc2lgmfidg724phhq6i-void-0.7.2-doc
/nix/store/zgbjzwbbc0h7w575z3sxqz13kfigdy0b-tagged-0.8.5
/nix/store/zjkc1abx2qmapdxpid9b86njabz37hcl-unordered-containers-0.2.9.0