Nix Language Quirks

with and let

with gets less priority then let. This can lead to confusions, especially if you like to write with pkgs;:

nix-repl> pkgs = { x = 1; }

nix-repl> with pkgs; x
1

nix-repl> with pkgs; let x = 2; in x
2

So we see, that let binding overrides with binding. But what about this?

nix-repl> let x = 2; in with pkgs; x
2

Nah, with and let have different priority when resolving names.

Good discussion on this topic

Old let syntax

This is an old Nix syntax, that probably isn't used much

nix-repl> let { x = 1; y = x + 1; body = y; }
2

It is equivalent to modern syntax expression let x = 1; y = x + 1; in y. Note, that it doesn't require rec keyword.

Note, that it isn't equivalent to with rec { x = 1; y = x + 1; body = y; }; body because of mentioned with and let quirk, but is same as rec { x = 1; y = x + 1; body = y; }.body