frontend: Add join() methods to Array and Vec

pkgs/std/collections.dora

@@ -82,6 +82,22 @@ impl[T: Zero] Array[T] {
   }
 }
 
+impl[T: Stringable] Array[T] {
+  pub fn join(separator: String): String {
+    let output = StringBuffer::new();
+
+    for (idx, element) in self.enumerate() {
+      if idx > 0 {
+        output.append(separator);
+      }
+
+      output.append(element.toString());
+    }
+
+    output.toString()
+  }
+}
+
 impl[T] IntoIterator for Array[T] {
   type IteratorType = ArrayIter[T];
 
@@ -1407,6 +1423,20 @@ impl[T: Stringable] Vec[T] {
     sb.append(")");
     return sb.toString();
   }
+
+  pub fn join(separator: String): String {
+    let output = StringBuffer::new();
+
+    for (idx, element) in self.enumerate() {
+      if idx > 0 {
+        output.append(separator);
+      }
+
+      output.append(element.toString());
+    }
+
+    output.toString()
+  }
 }
 
 impl[T1: Equals, T2: Equals] Equals for (T1, T2) {

tests/stdlib/array-join1.dora

@@ -0,0 +1,13 @@
+fn main() {
+    let x = Array[Int64]::new(1, 2, 3);
+    assert(x.join(", ") == "1, 2, 3");
+    assert(x.join("-") == "1-2-3");
+
+    let x = Array[Char]::new('a', 'b', 'c');
+    assert(x.join(", ") == "a, b, c");
+    assert(x.join("-") == "a-b-c");
+
+    let x = Array[Int64]::new(101, 102, 103);
+    assert(x.join(", ") == "101, 102, 103");
+    assert(x.join("-") == "101-102-103");
+}

tests/stdlib/vec-join1.dora

@@ -0,0 +1,13 @@
+fn main() {
+    let x = Vec[Int64]::new(1, 2, 3);
+    assert(x.join(", ") == "1, 2, 3");
+    assert(x.join("-") == "1-2-3");
+
+    let x = Vec[Char]::new('a', 'b', 'c');
+    assert(x.join(", ") == "a, b, c");
+    assert(x.join("-") == "a-b-c");
+
+    let x = Vec[Int64]::new(101, 102, 103);
+    assert(x.join(", ") == "101, 102, 103");
+    assert(x.join("-") == "101-102-103");
+}