Force-expand lists with more than one item

src/Nixfmt/Pretty.hs

@@ -91,21 +91,25 @@ prettyTerm (String s) = pretty s
 prettyTerm (Path p) = pretty p
 prettyTerm (Selection term selectors) = pretty term <> hcat selectors
 
+-- Empty list
 prettyTerm (List (Ann paropen Nothing []) [] parclose)
     = pretty paropen <> hardspace <> pretty parclose
 
+-- Singleton list
 prettyTerm (List (Ann paropen Nothing []) [item] parclose)
-    | isAbsorbable item
-        = pretty paropen <> pretty item <> pretty parclose
+        = pretty paropen <> hardspace <> pretty item <> hardspace <> pretty parclose
 
+-- General list
 prettyTerm (List (Ann paropen trailing leading) items parclose)
-    = base $ pretty paropen <> pretty trailing <> line
-        <> nest 2 (pretty leading <> sepBy line (map group items)) <> line
+    = base $ pretty paropen <> pretty trailing <> hardline
+        <> nest 2 (pretty leading <> sepBy hardline (map group items)) <> hardline
         <> pretty parclose
 
+-- Empty, non-recursive attribute set
 prettyTerm (Set Nothing (Ann paropen Nothing []) [] parclose)
     = pretty paropen <> hardspace <> pretty parclose
 
+-- General set
 prettyTerm (Set krec (Ann paropen trailing leading) binders parclose)
     = base $ pretty (fmap ((<>hardspace) . pretty) krec)
         <> pretty paropen <> pretty trailing <> line
@@ -160,7 +164,7 @@ isAbsorbable :: Term -> Bool
 isAbsorbable (String (Ann parts@(_:_:_) _ _))
     = not $ isSimpleString parts
 isAbsorbable (Set _ _ (_:_) _)                             = True
-isAbsorbable (List (Ann _ Nothing []) [item] _)            = isAbsorbable item
+isAbsorbable (List (Ann _ Nothing []) [_item] _)           = True
 isAbsorbable (Parenthesized (Ann _ Nothing []) (Term t) _) = isAbsorbable t
 isAbsorbable (List _ (_:_:_) _)                            = True
 isAbsorbable _                                             = False

test/diff/idioms_lib_2/out.nix

@@ -304,13 +304,16 @@ rec {
 
      Type: string -> a -> a
   */
-  warn =
-    if lib.elem (builtins.getEnv "NIX_ABORT_ON_WARN") [ "1" "true" "yes" ] then
-      msg:
-      builtins.trace "warning: ${msg}" (abort
-        "NIX_ABORT_ON_WARN=true; warnings are treated as unrecoverable errors.")
-    else
-      msg: builtins.trace "warning: ${msg}";
+  warn = if lib.elem (builtins.getEnv "NIX_ABORT_ON_WARN") [
+    "1"
+    "true"
+    "yes"
+  ] then
+    msg:
+    builtins.trace "warning: ${msg}" (abort
+      "NIX_ABORT_ON_WARN=true; warnings are treated as unrecoverable errors.")
+  else
+    msg: builtins.trace "warning: ${msg}";
 
   /* Like warn, but only warn when the first argument is `true`.
 
@@ -433,9 +436,7 @@ rec {
   toBaseDigits = base: i:
     let
       go = i:
-        if i < base then
-          [ i ]
-        else
+        if i < base then [ i ] else
           let
             r = i - ((i / base) * base);
             q = (i - r) / base;

test/diff/idioms_lib_3/out.nix

@@ -123,7 +123,11 @@ in rec {
   # For more examples see the test cases in ./tests/misc.nix.
   toINI = {
     # apply transformations (e.g. escapes) to section names
-      mkSectionName ? (name: libStr.escape [ "[" "]" ] name),
+      mkSectionName ? (name:
+        libStr.escape [
+          "["
+          "]"
+        ] name),
       # format a setting line from key and value
       mkKeyValue ? mkKeyValueDefault { } "=",
       # allow lists as values for duplicate keys
@@ -173,7 +177,11 @@ in rec {
   # the part in `sections`.
   toINIWithGlobalSection = {
     # apply transformations (e.g. escapes) to section names
-      mkSectionName ? (name: libStr.escape [ "[" "]" ] name),
+      mkSectionName ? (name:
+        libStr.escape [
+          "["
+          "]"
+        ] name),
       # format a setting line from key and value
       mkKeyValue ? mkKeyValueDefault { } "=",
       # allow lists as values for duplicate keys
@@ -265,7 +273,12 @@ in rec {
     }:
     assert builtins.isInt depthLimit;
     let
-      specialAttrs = [ "__functor" "__functionArgs" "__toString" "__pretty" ];
+      specialAttrs = [
+        "__functor"
+        "__functionArgs"
+        "__toString"
+        "__pretty"
+      ];
       stepIntoAttr = evalNext: name:
         if builtins.elem name specialAttrs then id else evalNext;
       transform = depth:
@@ -328,9 +341,18 @@ in rec {
         else if isString v then
           let
             lines = filter (v: !isList v) (builtins.split "\n" v);
-            escapeSingleline = libStr.escape [ "\\" ''"'' "\${" ];
-            escapeMultiline =
-              libStr.replaceStrings [ "\${" "''" ] [ "''\${" "'''" ];
+            escapeSingleline = libStr.escape [
+              "\\"
+              ''"''
+              "\${"
+            ];
+            escapeMultiline = libStr.replaceStrings [
+              "\${"
+              "''"
+            ] [
+              "''\${"
+              "'''"
+            ];
             singlelineResult = ''"''
               + concatStringsSep "\\n" (map escapeSingleline lines) + ''"'';
             multilineResult = let

test/diff/idioms_nixos_1/out.nix

@@ -139,7 +139,10 @@ in {
     boot.initrd.availableKernelModules = mkOption {
       type = types.listOf types.str;
       default = [ ];
-      example = [ "sata_nv" "ext3" ];
+      example = [
+        "sata_nv"
+        "ext3"
+      ];
       description = ''
         The set of kernel modules in the initial ramdisk used during the
         boot process.  This set must include all modules necessary for
@@ -276,12 +279,18 @@ in {
       # Implement consoleLogLevel both in early boot and using sysctl
       # (so you don't need to reboot to have changes take effect).
       boot.kernelParams = [ "loglevel=${toString config.boot.consoleLogLevel}" ]
-        ++ optionals config.boot.vesa [ "vga=0x317" "nomodeset" ];
+        ++ optionals config.boot.vesa [
+          "vga=0x317"
+          "nomodeset"
+        ];
 
       boot.kernel.sysctl."kernel.printk" =
         mkDefault config.boot.consoleLogLevel;
 
-      boot.kernelModules = [ "loop" "atkbd" ];
+      boot.kernelModules = [
+        "loop"
+        "atkbd"
+      ];
 
       # The Linux kernel >= 2.6.27 provides firmware.
       hardware.firmware = [ kernel ];

test/diff/idioms_pkgs_3/out.nix

@@ -139,7 +139,10 @@ in {
     boot.initrd.availableKernelModules = mkOption {
       type = types.listOf types.str;
       default = [ ];
-      example = [ "sata_nv" "ext3" ];
+      example = [
+        "sata_nv"
+        "ext3"
+      ];
       description = ''
         The set of kernel modules in the initial ramdisk used during the
         boot process.  This set must include all modules necessary for
@@ -276,12 +279,18 @@ in {
       # Implement consoleLogLevel both in early boot and using sysctl
       # (so you don't need to reboot to have changes take effect).
       boot.kernelParams = [ "loglevel=${toString config.boot.consoleLogLevel}" ]
-        ++ optionals config.boot.vesa [ "vga=0x317" "nomodeset" ];
+        ++ optionals config.boot.vesa [
+          "vga=0x317"
+          "nomodeset"
+        ];
 
       boot.kernel.sysctl."kernel.printk" =
         mkDefault config.boot.consoleLogLevel;
 
-      boot.kernelModules = [ "loop" "atkbd" ];
+      boot.kernelModules = [
+        "loop"
+        "atkbd"
+      ];
 
       # The Linux kernel >= 2.6.27 provides firmware.
       hardware.firmware = [ kernel ];

test/diff/let_in/out.nix

@@ -32,6 +32,10 @@ let
     # e
   in f;
 
-  a = let in [ 1 2 ];
+  a = let
+  in [
+    1
+    2
+  ];
 
 in a

test/diff/lists/out.nix

@@ -3,7 +3,10 @@
 
   [ 1 ]
 
-  [ b d ]
+  [
+    b
+    d
+  ]
   [
     b
     d # e

test/diff/monsters_3/out.nix

@@ -45,7 +45,13 @@ stdenv.mkDerivation rec {
     wrapGAppsHook4
     glib # for glib-compile-resources
   ];
-  buildInputs = [ cairo glib gtk4 libadwaita pango ];
+  buildInputs = [
+    cairo
+    glib
+    gtk4
+    libadwaita
+    pango
+  ];
   postPatch = ''
     patchShebangs build-aux/meson_post_install.py
     # https://gitlab.gnome.org/World/design/contrast/-/merge_requests/23

test/diff/pattern/out.nix

@@ -26,7 +26,11 @@
     }@inp:
     _)
   ({
-      a ? [ 1 2 3 ],
+      a ? [
+        1
+        2
+        3
+      ],
       b ? {
         # ...
       }

test/diff/with/out.nix

@@ -43,5 +43,11 @@
       b = 2;
     })
   { a = with b; with b; with b; 1; }
-  { binPath = with pkgs; makeBinPath ([ rsync util-linux ]); }
+  {
+    binPath = with pkgs;
+      makeBinPath ([
+        rsync
+        util-linux
+      ]);
+  }
 ]