#lang plait
number: DIGIT number
eval(0) = 0
eval(1) = 1
...
eval(9) = 9
eval(DIGIT) = DIGIT
eval(DIGIT number) = 10*eval(DIGIT) + eval(number)
#lang plait
number: DIGIT number
eval(0) = 0
eval(1) = 1
...
eval(9) = 9
eval(DIGIT) = DIGIT
eval(DIGIT number) = 10*eval(DIGIT) + eval(number)