feat: collapse nested lambdas

src/rules/lambda.rs

@@ -14,7 +14,16 @@ pub fn rule(
 
     // a
     let child = children.get_next().unwrap();
-    steps.push_back(crate::builder::Step::Format(child.element));
+    let is_pattern_type =
+        child.element.kind() == rnix::SyntaxKind::NODE_PATTERN;
+    match layout {
+        crate::config::Layout::Tall => {
+            steps.push_back(crate::builder::Step::FormatWider(child.element));
+        }
+        crate::config::Layout::Wide => {
+            steps.push_back(crate::builder::Step::Format(child.element));
+        }
+    }
 
     if let rnix::SyntaxKind::TOKEN_COMMENT =
         children.peek_next().unwrap().element.kind()
@@ -35,29 +44,53 @@ pub fn rule(
     match layout {
         crate::config::Layout::Tall => {
             steps.push_back(crate::builder::Step::FormatWider(child.element));
-            steps.push_back(crate::builder::Step::NewLine);
-            steps.push_back(crate::builder::Step::Pad);
         }
         crate::config::Layout::Wide => {
             steps.push_back(crate::builder::Step::Format(child.element));
-            steps.push_back(crate::builder::Step::Whitespace);
         }
     }
 
     // /**/
     children.drain_comments(|text| {
-        steps.push_back(crate::builder::Step::Comment(text));
         steps.push_back(crate::builder::Step::NewLine);
         steps.push_back(crate::builder::Step::Pad);
+        steps.push_back(crate::builder::Step::Comment(text));
     });
 
     // c
+    let child_prev = children.peek_prev().unwrap();
     let child = children.get_next().unwrap();
     match layout {
         crate::config::Layout::Tall => {
+            if is_pattern_type {
+                steps.push_back(crate::builder::Step::NewLine);
+                steps.push_back(crate::builder::Step::Pad);
+            } else if let rnix::SyntaxKind::TOKEN_COMMENT =
+                child_prev.element.kind()
+            {
+                steps.push_back(crate::builder::Step::NewLine);
+                steps.push_back(crate::builder::Step::Pad);
+            } else if child.element.kind() == rnix::SyntaxKind::NODE_LAMBDA
+                && child
+                    .element
+                    .clone()
+                    .into_node()
+                    .unwrap()
+                    .children_with_tokens()
+                    .next()
+                    .unwrap()
+                    .kind()
+                    == rnix::SyntaxKind::NODE_IDENT
+            {
+                steps.push_back(crate::builder::Step::Whitespace);
+            } else {
+                steps.push_back(crate::builder::Step::NewLine);
+                steps.push_back(crate::builder::Step::Pad);
+            }
             steps.push_back(crate::builder::Step::FormatWider(child.element));
         }
         crate::config::Layout::Wide => {
+            steps.push_back(crate::builder::Step::Whitespace);
             steps.push_back(crate::builder::Step::Format(child.element));
         }
     }

src/rules/pattern.rs

@@ -40,18 +40,17 @@ pub fn rule(
                 steps.push_back(crate::builder::Step::FormatWider(
                     child.element,
                 ));
-                if !has_comments && items_count <= 1 {
-                    steps.push_back(crate::builder::Step::Whitespace);
-                } else {
-                    steps.push_back(crate::builder::Step::NewLine);
-                    steps.push_back(crate::builder::Step::Pad);
-                }
             }
             crate::config::Layout::Wide => {
                 steps.push_back(crate::builder::Step::Format(child.element));
-                steps.push_back(crate::builder::Step::Whitespace);
             }
         }
+        if !has_comments && items_count <= 1 {
+            steps.push_back(crate::builder::Step::Whitespace);
+        } else {
+            steps.push_back(crate::builder::Step::NewLine);
+            steps.push_back(crate::builder::Step::Pad);
+        }
         children.move_next();
     }
 
@@ -152,18 +151,11 @@ pub fn rule(
 
     // }
     let child = children.get_next().unwrap();
-    match layout {
+    if !has_comments_between_curly_b && items_count <= 1 {
-        crate::config::Layout::Tall => {
+        steps.push_back(crate::builder::Step::Whitespace);
-            if !has_comments_between_curly_b && items_count <= 1 {
+    } else {
-                steps.push_back(crate::builder::Step::Whitespace);
+        steps.push_back(crate::builder::Step::NewLine);
-            } else {
+        steps.push_back(crate::builder::Step::Pad);
-                steps.push_back(crate::builder::Step::NewLine);
-                steps.push_back(crate::builder::Step::Pad);
-            }
-        }
-        crate::config::Layout::Wide => {
-            steps.push_back(crate::builder::Step::Whitespace);
-        }
     }
     steps.push_back(crate::builder::Step::Format(child.element));
 
@@ -177,20 +169,19 @@ pub fn rule(
     // @ x
     if let Some(child) = children.peek_next() {
         if let rnix::SyntaxKind::NODE_PAT_BIND = child.element.kind() {
+            if !has_comments && items_count <= 1 {
+                steps.push_back(crate::builder::Step::Whitespace);
+            } else {
+                steps.push_back(crate::builder::Step::NewLine);
+                steps.push_back(crate::builder::Step::Pad);
+            }
             match layout {
                 crate::config::Layout::Tall => {
-                    if !has_comments && items_count <= 1 {
-                        steps.push_back(crate::builder::Step::Whitespace);
-                    } else {
-                        steps.push_back(crate::builder::Step::NewLine);
-                        steps.push_back(crate::builder::Step::Pad);
-                    }
                     steps.push_back(crate::builder::Step::FormatWider(
                         child.element,
                     ));
                 }
                 crate::config::Layout::Wide => {
-                    steps.push_back(crate::builder::Step::Whitespace);
                     steps
                         .push_back(crate::builder::Step::Format(child.element));
                 }

tests/cases/lambda/in

@@ -1,4 +1,7 @@
 [
+  (a: b: /*c*/ d)
+  ({}: b: /*c*/ d)
+  (a: {}: /*c*/ d)
   (a       :       d)
   (a       : /*c*/ d)
   (a /*b*/ :       d)
@@ -7,4 +10,5 @@
     aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
   )
   ( aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa )
+  ({ pkgs ? import ./.. { }, locationsXml }: null)
 ]

tests/cases/lambda/out

@@ -1,4 +1,27 @@
 [
+  (
+    a: b:
+    /*
+     c
+     */
+    d
+  )
+  (
+    { }:
+    b:
+    /*
+     c
+     */
+    d
+  )
+  (
+    a:
+    { }:
+    /*
+     c
+     */
+    d
+  )
   (a: d)
   (
     a:
@@ -31,4 +54,10 @@
     aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa:
     aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
   )
+  (
+    { pkgs ? import ./.. { }
+    , locationsXml
+    }:
+    null
+  )
 ]

tests/cases/pattern/out

@@ -26,7 +26,13 @@
     }:
     _
   )
-  ({ b, e, ... }: _)
+  (
+    { b
+    , e
+    , ...
+    }:
+    _
+  )
   (
     { b
     , e