pkg/list: remove use of :: (Incompatible!!!)

WARNING: this change causes a breaking change.

Change-Id: I379b5db972e30d0de81096c7ddac115064658d6d
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/6201
Reviewed-by: CUE cueckoo <cueckoo@gmail.com>
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>

pkg/list/sort.cue

@@ -15,8 +15,8 @@
 package list
 
 // A Comparer specifies whether one value is strictly less than another value.
-Comparer :: {
-	T ::  _
+Comparer: {
+	T:    _
 	x:    T
 	y:    T
 	less: bool // true if x < y
@@ -26,11 +26,11 @@ Comparer :: {
 //
 // Example:
 //     list.Sort(a, list.Ascending)
-Ascending :: {
+Ascending: {
 	Comparer
-	T :: number | string
-	x:   T
-	y:   T
+	T: number | string
+	x: T
+	y: T
 	// TODO: the following will be fixed when removing old-school templating.
 	less: true && (x < y)
 }
@@ -39,9 +39,9 @@ Ascending :: {
 //
 // Example:
 //     list.Sort(a, list.Descending)
-Descending :: {
+Descending: {
 	Comparer
-	T ::  number | string
+	T:    number | string
 	x:    T
 	y:    T
 	less: (x > y)

pkg/list/sort.go

@@ -42,7 +42,7 @@ func (s *valueSorter) Less(i, j int) bool { panic("implemented in cue/builtinuti
 // Sort sorts data. It does O(n*log(n)) comparisons.
 // The sort is not guaranteed to be stable.
 //
-// cmp is a struct of the form {T :: _, x: T, y: T, less: bool}, where
+// cmp is a struct of the form {T: _, x: T, y: T, less: bool}, where
 // less should reflect x < y.
 //
 // Example: