`?` reads the right-hand side as an identifier, according to the reference:
noogle.dev/f/builtins/h...
noogle.dev/f/builtins/h...
builtins.hasAttr - Nix function reference
hasAttr returns true if set has an attribute named s, and
false otherwise. This is a dynamic version of the ? operator,
since s is an expression rather than an identifier.
noogle.dev
December 24, 2025 at 1:36 PM
`?` reads the right-hand side as an identifier, according to the reference:
noogle.dev/f/builtins/h...
noogle.dev/f/builtins/h...