List.sortWith given invalid order function causes compiler to hang

[mordrax]

List.sortWith (Tuple.second >> (>)) [("a",4),("d",7),("b",6)]

causes my 0.18 compiler to hang, cpu and memory goes through the roof.

I fixed this by realising that the order function is completely wrong and that I should have gone with

List.sortBy Tuple.second [("a", 4), ... ]

However, the usually friendly compiler got very confused and never returned.

[process-bot]

Thanks for the issue! Make sure it satisfies this checklist. My human colleagues will appreciate it!

Here is what to expect next, and if anyone wants to comment, keep these things in mind.

[process-bot]

Thanks for the issue! Make sure it satisfies this checklist. My human colleagues will appreciate it!

Here is what to expect next, and if anyone wants to comment, keep these things in mind.

[evancz]

This is "infinite types can hang rather than give a nice error" problem. The upcoming error is like this:

-- INFINITE TYPE ------------------ /Users/evan/Documents/pkgs/core/src/List.elm

I am inferring a weird self-referential type for the 1st argument to function
`sortWith`:

57|   sortWith (Tuple.second >> (>)) [("a",4),("d",7),("b",6)]
                ^^^^^^^^^^^^^^^^^^^
Here is my best effort at writing down the type. You will see ∞ for parts of the
type that repeat something already printed out infinitely.

    ( comparable, ∞ ) -> ( comparable, ∞ ) -> Order

Usually staring at the type is not so helpful in these cases, so definitely read
the debugging hints for ideas on how to figure this out:
<https://github.com/elm-lang/elm-compiler/blob/0.19.0/hints/infinite-type.md>

Probably could be improved, but that is for https://github.com/elm-lang/error-message-catalog

[evancz]

This is "infinite types can hang rather than give a nice error" problem. The upcoming error is like this:

-- INFINITE TYPE ------------------ /Users/evan/Documents/pkgs/core/src/List.elm

I am inferring a weird self-referential type for the 1st argument to function
`sortWith`:

57|   sortWith (Tuple.second >> (>)) [("a",4),("d",7),("b",6)]
                ^^^^^^^^^^^^^^^^^^^
Here is my best effort at writing down the type. You will see ∞ for parts of the
type that repeat something already printed out infinitely.

    ( comparable, ∞ ) -> ( comparable, ∞ ) -> Order

Usually staring at the type is not so helpful in these cases, so definitely read
the debugging hints for ideas on how to figure this out:
<https://github.com/elm-lang/elm-compiler/blob/0.19.0/hints/infinite-type.md>

Probably could be improved, but that is for https://github.com/elm-lang/error-message-catalog