Monads for functional programming, Advanced Functional Programming (1995)

by Philip Wadler
Venue:x, t) 9 | x == 0 = 1 10 | x == ?nx = 0 11 | t == 0 = 0 12 | otherwise = h’ (x, t-1) + r * (h’ (x+1, t-1) - 2 * h’ (x, t-1) + h’ (x-1, t-1)) 13 where r = ?alpha * (?dt / (?dx * ?dx