scala - Accessing the Accumulator & Element in `foldl` -


in scala's foldleft, know how access accumulator , element values in scala, not haskell.

i use foldleft find out, between 1 , 100, how many numbers have remainder of 1 when divided 3:

scala> list.range(1, 101).foldleft(0){ (acc, elem) =>      |    if (elem % 3 == 1) acc + 1      |    else acc      | } res2: int = 33

how can same in haskell?

this direct translation of scala code haskell:

foldl (\acc x -> if x `mod` 3 == 1 acc + 1 else acc) 0 [1..100]

in haskell, because of laziness of it, using foldl not idea, better choose foldl' or foldr, here foldr version:

foldr (\x acc -> if x `mod` 3 == 1 acc + 1 else acc) 0 [1..100]

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