List does not throw runtime exceptions

[laszlopandy]

• Changed type List.head : List a -> Maybe a
• Deleted List.tail in favour of List.drop 1
• Deleted List.foldl1, List.foldr1, List.scanl1
• Added List.uncons
• Changed List.maximum and List.minimum to take default values

[evancz]

This code does extra traversals compared to the old way. I don't know how big a deal that is, but I wrote it the old way with this in mind.

[evancz]

I think this is buggy. s is the leftmost thing, but it is used as the rightmost. I think foldr needs the last element.

[laszlopandy]

I did a reverse and foldl. I'm pretty sure this is equivalent to foldr, but please check if over again.

[evancz]

I think it is often hard to pick a minimum value. I'm imagining people writing minimum (maximum 0 xs) xs.

Why did you go for this instead of returning a maybe?

[evancz]

I am having a hard time evaluating this change without any examples as data.

[laszlopandy]

Yeah I just realized today that there is a difference between a default
value (which will be ignored if the list is non-empty) and a base value for
foldl.

So I will change it back to maybe.

On Saturday, January 10, 2015, Evan Czaplicki notifications@github.com
wrote:

In src/List.elm
https://github.com/elm-lang/core/pull/90#discussion-diff-22759619:

-}
-minimum : List comparable -> comparable
-minimum = foldl1 min
+minimum : comparable -> List comparable -> comparable
+minimum def list = foldl min def list

I am having a hard time evaluating this change without any examples as
data.

—
Reply to this email directly or view it on GitHub
https://github.com/elm-lang/core/pull/90/files#r22759619.