Does this work if justStaticExecutables is not enabled?

dang!, yeah, it only works if justStaticExecutables is also ran over it

i'm not sure if anything can be done about that, things like libHSpurescript-0.11.5-ELQ93PZ2tNq8ropwfk7fQs-ghc8.0.2.dylib are referencing ghc

That's what static means, it compiles haskell packages statically. Otherwise it does need to depend on warp.

So we should only enable reference stripping for pkgs.purescript.

when cabal auto-generates the Paths_warp[1] module, it creates a bindir variable, pointing to ${warp}/bin/, which lands in the ${warp}/lib/ghc-8.0.2/warp-3.2.11.2/Paths_warp.hi

using [2] i can then see

  bindir :: FilePath
  {- Unfolding: (unpackCString#
                   "/nix/store/6i6bs80l129d6mlij6zdd63m1gydgfxw-warp-3.2.11.2/bin"#) -}

but under linux, when dead-code elimination is working, that path vanishes from the final ${purescript}/bin/purs binary

[1] https://github.com/yesodweb/wai/blob/master/warp/warp.cabal#L102
[2] https://ghc.haskell.org/trac/ghc/wiki/Commentary/Compiler/IfaceFiles

this fix may also work for #21200

the latest commit enables -dead-strip for justStaticExecutables, which shrinks the closure for purescript, and also shrinks the main output for things like hlint from 30mb to 19mb and pandoc from 129mb to 106mb