Trying to follow you: is in the following expression applied what you mean by
different types in the folding?
> Prelude> foldl (\(x,y) e -> (y,x+e)) (0,2) [1..5]
> (8,9)
Which I would translate into J like e.g:
;({:@],[+{.@])&.>/(;/1+i.5),<0 2
8 9
I can ask Haskell (GHCi interpreter) what this 'whole thing' is typed like:
Prelude> :t foldl (\(x,y) e -> (y,x+e))
foldl (\(x,y) e -> (y,x+e)) :: (Num b) => (b, b) -> [b] -> (b, b)
We have an initial element as tupel (a,a), a list [a] which results in a tupel
(a,a).
The basic type is here is Num b (Numeric b) because I apply (+) on b's.
b can be e.g. of type Int, Integer, Double
--
Met vriendelijke groet,
=@@i
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