i'm beginner in haskell terms. have exercise shows minimum positions. example: [1,2,3,1,1] => 0,3,4 these minimum positions. tried in 2 ways, these doesn't work. please can me recursive version?
first:
findpos :: [int]->int->[int] findpos list minimum (list) = [index | (index, e) <- zip [0..] list, e == minimum (list)] second:
findpos :: [int]->int->[int] findpos list (minim el) = [index | (index, e) <- zip [0..] list, e == (minim el)] minim :: [int] -> int minim x = if (tail(x)==[]) head(x) else n n = minim (tail(x)) n = if n < head(x) n else head(x)
the serious problem code have strange on left of function definitions.
in first case have:
findpos :: [int] -> int-> [int] findpos list minimum (list) = … what mean? judging signature gave findpos, takes list , element looking for. the definition has be:
findpos list m = [index | (index, e) <- zip [0..] list, e == m] and in case there no need call minim function on right hand side, instead you’ll have call minim before calling findpos pass minimal element this:
findpos' :: [int] -> [int] findpos' list = findpos list (minim list) or can change definition to:
findpos :: [int] -> [int] findpos list = [index | (index, e) <- zip [0..] list, e == minim list] and in case call minim on right hand side, signature of findpos becomes different.
now recursive minimum function. should use pattern matching as possible:
minim :: [int] -> int minim (x : []) = x minim (x : xs) = if x < m x else m m = minim xs otherwise minim correct except fact define n twice.
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