guile-algorithms/graphs/lib/distances.scm

(library (distances)
  (export manhattan)
  (import
   (except (rnrs base) let-values map error)
   (only (guile)
         lambda* λ))

  (define manhattan
    (λ (y1 y2 x1 x2)
      (+ (abs (- y1 y2))
         (abs (- x1 x2))))))