Add Sort ability

This adds a Sort ability, currently lacking any implementations of the
ability.

It's an open question whether this should be defined in a new top-level
Roc builtin. I can also see an argument for putting it in the List
module, and maybe there's other options. I plan to get some input on
this point before making a decision.

crates/compiler/builtins/roc/List.roc

@@ -69,6 +69,8 @@ module [
     walkBackwardsUntil,
     countIf,
     chunksOf,
+    Sort,
+    compare,
 ]
 
 import Bool exposing [Bool, Eq]
@@ -1324,3 +1326,6 @@ iterBackwardsHelp = \list, state, f, prevIndex ->
             Break b -> Break b
     else
         Continue state
+
+Sort implements
+    compare : a, a -> [LessThan, Equal, GreaterThan] where a implements Sort

crates/compiler/builtins/roc/main.roc

@@ -6,6 +6,7 @@ package [
     List,
     Dict,
     Set,
+    Sort
     Decode,
     Encode,
     Hash,

crates/compiler/module/src/symbol.rs

@@ -53,6 +53,7 @@ pub const DERIVABLE_ABILITIES: &[(Symbol, &[Symbol])] = &[
     (Symbol::DECODE_DECODING, &[Symbol::DECODE_DECODER]),
     (Symbol::HASH_HASH_ABILITY, &[Symbol::HASH_HASH]),
     (Symbol::BOOL_EQ, &[Symbol::BOOL_IS_EQ]),
+    (Symbol::LIST_SORT, &[Symbol::LIST_COMPARE]),
     (
         Symbol::INSPECT_INSPECT_ABILITY,
         &[Symbol::INSPECT_TO_INSPECTOR],
@@ -1739,6 +1740,10 @@ define_builtins! {
         5 JSON_ARRAY_CLOSING_STATE: "ArrayClosingState"
         6 JSON_OBJECT_STATE: "ObjectState"
     }
+    16 SORT: "Sort" => {
+        0 LIST_SORT: "Sort"
+        1 LIST_COMPARE: "compare"
+    }
 
-    num_modules: 16 // Keep this count up to date by hand! (TODO: see the mut_map! macro for how we could determine this count correctly in the macro)
+    num_modules: 17 // Keep this count up to date by hand! (TODO: see the mut_map! macro for how we could determine this count correctly in the macro)
 }