Fix formatter bugs (#1619)

pkl-formatter/src/main/java/org/pkl/formatter/Builder.java

@@ -166,7 +166,13 @@ final class Builder {
     var nodes =
         formatGeneric(
             node.children,
-            (prev, next) -> linesBetween(prev, next) > 1 ? TWO_NEWLINES : forceLine());
+            (prev, next) -> {
+              var sep = linesBetween(prev, next) > 1 ? TWO_NEWLINES : forceLine();
+              if (prev.type == NodeType.MODULE_DECLARATION || prev.type == NodeType.IMPORT_LIST) {
+                sep = TWO_NEWLINES;
+              }
+              return sep;
+            });
     return new Nodes(nodes);
   }
 
@@ -697,9 +703,20 @@ final class Builder {
   /**
    * Tells if an argument list has a trailing lambda, new expr, or amends expr.
    *
-   * <p>Only considered trailing lamdba if: 1. There is only one lambda/new expr/amends expr in the
-   * list. E.g. avoid formatting `toMap()` weirdly: ``` foo.toMap( (it) -> makeSomeKey(it), (it) ->
-   * makeSomeValue(it), ) ``` 2. The lambda does not have leading or trailing line comment.
+   * <p>Only considered trailing lambda if and only if:
+   *
+   * <ol>
+   *   <li>There is only one lambda/new expr/amends expr in the list.
+   *       <p>E.g. avoid formatting {@code toMap()} weirdly:
+   *       <pre>{@code
+   * foo.toMap((it) -> makeSomeKey(it), (it) ->
+   *   makeSomevalue(it)
+   * )
+   *
+   * }</pre>
+   *   <li>The lambda does not have leading or trailing line comment.
+   *   <li>The user has not broken 3+ arguments across lines.
+   * </ol>
    */
   private boolean hasTrailingLambda(Node argList) {
     var elementsNode = firstProperChild(argList);
@@ -707,6 +724,10 @@ final class Builder {
     var children = elementsNode.children;
     var seenLambda = false;
     if (children.get(children.size() - 1).type == NodeType.LINE_COMMENT) return false;
+    var properArgCount = 0;
+    for (var child : children) {
+      if (isProper(child)) properArgCount++;
+    }
     for (var i = children.size() - 1; i >= 0; i--) {
       var child = children.get(i);
       if (!isProper(child)) continue;
@@ -719,7 +740,7 @@ final class Builder {
         return false;
       }
     }
-    return true;
+    return properArgCount <= 2 || !shouldMultilineNodes(elementsNode, n -> isTerminal(n, ","));
   }
 
   private List<Node> pairArguments(List<Node> nodes) {

pkl-formatter/src/test/files/FormatterSnippetTests/input/module.pkl

@@ -0,0 +1,3 @@
+module foo
+import "pkl:json"
+foo: Int = 10

pkl-formatter/src/test/files/FormatterSnippetTests/input/trailing-objects.pkl

@@ -0,0 +1,7 @@
+
+foo =
+  bar("string",
+    true, new Baz {
+      name = "name"
+      num = 10
+    })

pkl-formatter/src/test/files/FormatterSnippetTests/output/module.pkl

@@ -0,0 +1,5 @@
+module foo
+
+import "pkl:json"
+
+foo: Int = 10

pkl-formatter/src/test/files/FormatterSnippetTests/output/trailing-objects.pkl

@@ -0,0 +1,9 @@
+foo =
+  bar(
+    "string",
+    true,
+    new Baz {
+      name = "name"
+      num = 10
+    },
+  )