Layering environments Because .envrc files are scripts, you can add as many use flake statements as you want, which enables you to layer Nix environments. Here’s an example .envrc:

Terminal window use flake "github:the-nix-way/dev-templates?dir=elixir" use flake "github:the-nix-way/dev-templates?dir=gleam"

In this case, both an Elixir and a Gleam environment would be applied to the current directory. This may not always be the best idea, as Nix honors the flake listed last in case of a clash, for example in the case of two packages named cargo that refer to different versions of Cargo. But if you apply due care, you can reap the benefits of layered environments without being stung by ambiguity.

https://determinate.systems/blog/nix-direnv/