scrambled
scrambled
Concept

Parallel simultaneous let

Modified just now
Books JourneyProgramming Language Theory Statuslearning
scheme
(let ([x 1]
      [y (+ x 1)])  ; this x refers to outer scope, not the x being bound
  (+ x y))
; Error if no outer x exists

Python's multi-assignment's semantic is similar to parallel let:

python
x = 1
y = 2
x, y = y, x + y
## X => 2, y => 3
## RHS evaluated first: (2, 1+2) => (2, 3)
## Then both assigned simultaneously