[clean-list] order of parameters of "fwrites"

[Marco Kesseler]

erik.zuurbier at tiscali.nl wrote:

>One reason is the possibility to chain various write-functions with <<< 
>as follows:
>where file1 = file <<< fwritec 'A' <<< fwritei 12 <<< 
>fwrites "abc"
>
>  
>
Funny that you mention this, because the type of (<<<) actually  is:

class (<<<) infixl a :: !*File !a -> *File

which is exactly the kind of argument reversal that the original poster 
suggested. The compiler won't accept the code above.  The expression 
goes like: file <<< 'A' <<< 12 <<< "abc". The instance definitions for 
<<< actually reverse the arguments before mapping onto fwrites, fwritei, 
etc.

Now as to the original fold problem: you can also solve this by defining 
a fold that applies the arguments in the reverse order to the operation.

rfoldl op r l :== foldl r l
    where
        foldl r []        = r
        foldl r [a:x]    = foldl (op a r) x

regards
Marco