dhall-nix Use z-encoding for nix symbol names

[Profpatsch]

When trying to encode a function like

\(Foo/Bar: Text) -> Foo/Bar

I get the nix code

Foo/Bar:
  Foo/Bar

which fails with the nix parsing error

error: syntax error, unexpected ':', expecting end of file

       at «string»:1:8:

            1| Foo/Bar:
             |        ^

… this is not good, because “namespaced” symbols like that are quite frequent in dhall code.

I would suggest using the Z-Encoding scheme that is also used by GHC to create nix symbols.

[Gabriella439]

You can escape identifiers using backticks, like this:

λ(`Foo/Bar` : Text) → `Foo/Bar`

[Profpatsch]

Yeah, but the generated nix code is still not valid nix syntax, this generates

Foo/Bar:
  Foo/Bar