Let expression?

[ahdinosaur]

let (a = 10, b = 20) { a + b }

let (
  a = 10,
  b = 20,
  c = 40,
) {
  a + b / c
}

OR

let a = 10, b = 20 { a + b }

let
  a = 10,
  b = 20,
  c = 40,
{
  a + b / c
}

[ahdinosaur]

or

let (a = 10, b = 20) => a + b

let (
  a = 10,
  b = 20,
  c = 40,
) => a + b / c

[ahdinosaur]

or inspired by Nix's expression language

let a = 10, b = 20 in a + b

let
  a = "oh my",
  b = "hello",
  c = "world",
in join([a, b, c], " ")