Documentation

Paths are non-empty lists of identifiers in Nix.

>>> path # [ident # "yo"]
Path [Identifier "yo"]

Any attempt to construct the empty path throws an error:

>>> :set -XScopedTypeVariables
>>> either (\(_::SomeException) -> "empty paths are illegal") show <$> Excpt.try (evaluate (path # []))
"empty paths are illegal"

Paths can be pretty-printed and parsed with the Text class:

>>> parse "Path" "foo.\"foo.bar\".bar" :: Path
Path [Identifier "foo",Identifier "foo.bar",Identifier "bar"]
>>> pPrint (parse "Path" "foo.\"foo\".\"bar\".bar" :: Path)
foo.foo.bar.bar

\p -> Just (p :: Path) == parseM "Path" (prettyShow p)

Paths are instances of strings and can be implicitly converted:

>>> :set -XOverloadedStrings
>>> pPrint $ ("yo.bar" :: Path)
yo.bar
>>> pPrint $ ("  yo  .  bar" :: Path)
yo.bar

Freaky quoted identifiers are fine throughout:

>>> pPrint $ path # ["yo","b\"ar"]
yo."b\"ar"
>>> pPrint ("\"5ident\"" :: Path)
"5ident"
>>> pPrint $ path # ["5ident","foo.bar","foo\nbar"]
"5ident"."foo.bar"."foo\nbar"

Use this isomorphism to construct a path from a list of identifiers, or to access that list for a given path.