Update generic syntax in tests.

examples/tests/d/lib/main.ak

@@ -1,15 +1,15 @@
-pub fn foldr(xs: List(a), f: fn(a, b) -> b, zero: b) -> b {
+pub fn foldr(xs: List<a>, f: fn(a, b) -> b, zero: b) -> b {
   when xs is {
     [] -> zero
     [x, ..rest] -> f(x, foldr(rest, f, zero))
   }
 }
 
-pub fn prepend(x: a, xs: List(a)) -> List(a) {
+pub fn prepend(x: a, xs: List<a>) -> List<a> {
   [x, ..xs]
 }
 
-pub fn concat(left: List(a), right: List(a)) -> List(a) {
+pub fn concat(left: List<a>, right: List<a>) -> List<a> {
   foldr(left, prepend, right)
 }