RosettaCodeData/Task/Happy-numbers/Miranda/happy-numbers.miranda
2023-07-01 13:44:08 -04:00

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Text

main :: [sys_message]
main = [Stdout (lay (map show (take 8 happynumbers)))]
happynumbers :: [num]
happynumbers = filter ishappy [1..]
ishappy :: num->bool
ishappy n = 1 $in loop (iterate sumdigitsquares n)
sumdigitsquares :: num->num
sumdigitsquares 0 = 0
sumdigitsquares n = (n mod 10)^2 + sumdigitsquares (n div 10)
loop :: [*]->[*]
loop = loop' []
where loop' mem (a:as) = mem, if a $in mem
= loop' (a:mem) as, otherwise
in :: *->[*]->bool
in val [] = False
in val (a:as) = True, if a=val
= val $in as, otherwise