> Summary: the Haskell 98 Report claims
>
> minimumBy :: (a -> a -> Ordering) -> [a] -> a
>
> but Hugs and GHC implement
>
> minimumBy :: (a -> a -> a) -> [a] -> a
> minimumBy = foldl1
The Haskell report says first
mimimumBy :: (a -> a -> Ordering) -> [a] -> a
in 7.7 - where the types are declared. And I like this.
In 7.8 it gives the "definition":
mimimumBy :: (a -> a -> a) -> [a] -> a
as foldl min.
Which I dislike.
So, in my programs, I use
minBy :: (a -> a -> Ordering) -> [a] -> a
minBy _ [] = error "minBy _ []\n"
minBy cp xs = m xs
where m [x] = x
m (x:y:xs) = case cp x y of GT -> m (y:xs)
_ -> m (x:xs)
And this implementation has also more chances to run without stack
overflow.
Probably, it is good to improve minimumBy in this manner.
Also it agrees with the type of sortBy.
Suggestion for standard library:
--------------------------------
to remove the names minimum(By), maximum(By)
and to make min(By), max(By), gcd, lcm
for the lists only.
For example,
min [x,y], min [x,y,x,u], minBy compare [x,y,x,u]
gcd [4,6], gcd [4,6,4], gcd [4]
This is for the economy of function names. Less names to recall.
------------------
Sergey Mechveliani
[EMAIL PROTECTED]
