Nix variables
From wikinotes
scope
var = "value" # assign variable (global)
# under 'let' variables are local to current scope
let
local_var = "value"
other_var = "value"
with
'with' exposes set keys as local variables within scope
fn = x:
with { a="A"; b="B"; c=x }
a + b + c
fn "C"
"ABC"