lib: introduce imap0, imap1 (#25543)

* lib: introduce imap0, imap1

For historical reasons, imap starts counting at 1 and it's not
consistent with the rest of the lib.

So for now we split imap into imap0 that starts counting at zero and
imap1 that starts counting at 1. And imap is marked as deprecated.

See https://github.com/NixOS/nixpkgs/commit/c71e2d42359f9900ea2c290d141c0d606471da16#commitcomment-21873221

* replace uses of lib.imap

* lib: move imap to deprecated.nix

11 files changed, 31 insertions, 17 deletions

diff --git a/lib/deprecated.nix b/lib/deprecated.nix
index 983e8d26892bf..d4e78c39250cf 100644
--- a/lib/deprecated.nix
+++ b/lib/deprecated.nix
@@ -423,4 +423,12 @@ rec {
       else if isInt x then "int"
       else "string";
 
+  /* deprecated:
+
+     For historical reasons, imap has an index starting at 1.
+
+     But for consistency with the rest of the library we want an index
+     starting at zero.
+  */
+  imap = imap1;
 }
diff --git a/lib/lists.nix b/lib/lists.nix
index fd746f4f97b1f..a04b1b278935a 100644
--- a/lib/lists.nix
+++ b/lib/lists.nix
@@ -77,15 +77,21 @@ rec {
   */
   foldl' = builtins.foldl' or foldl;
 
-  /* Map with index
+  /* Map with index starting from 0
 
-     FIXME(zimbatm): why does this start to count at 1?
+     Example:
+       imap0 (i: v: "${v}-${toString i}") ["a" "b"]
+       => [ "a-0" "b-1" ]
+  */
+  imap0 = f: list: genList (n: f n (elemAt list n)) (length list);
+
+  /* Map with index starting from 1
 
      Example:
-       imap (i: v: "${v}-${toString i}") ["a" "b"]
+       imap1 (i: v: "${v}-${toString i}") ["a" "b"]
        => [ "a-1" "b-2" ]
   */
-  imap = f: list: genList (n: f (n + 1) (elemAt list n)) (length list);
+  imap1 = f: list: genList (n: f (n + 1) (elemAt list n)) (length list);
 
   /* Map and concatenate the result.
 
diff --git a/lib/modules.nix b/lib/modules.nix
index 91e2eae0595e3..3da689a6bdb00 100644
--- a/lib/modules.nix
+++ b/lib/modules.nix
@@ -98,7 +98,7 @@ rec {
   /* Close a set of modules under the ‘imports’ relation. */
   closeModules = modules: args:
     let
-      toClosureList = file: parentKey: imap (n: x:
+      toClosureList = file: parentKey: imap1 (n: x:
         if isAttrs x || isFunction x then
           let key = "${parentKey}:anon-${toString n}"; in
           unifyModuleSyntax file key (unpackSubmodule (applyIfFunction key) x args)
diff --git a/lib/strings.nix b/lib/strings.nix
index 1cc633c729dcc..a03694d1b1d72 100644
--- a/lib/strings.nix
+++ b/lib/strings.nix
@@ -33,7 +33,7 @@ rec {
        concatImapStrings (pos: x: "${toString pos}-${x}") ["foo" "bar"]
        => "1-foo2-bar"
   */
-  concatImapStrings = f: list: concatStrings (lib.imap f list);
+  concatImapStrings = f: list: concatStrings (lib.imap1 f list);
 
   /* Place an element between each element of a list
 
@@ -70,7 +70,7 @@ rec {
        concatImapStringsSep "-" (pos: x: toString (x / pos)) [ 6 6 6 ]
        => "6-3-2"
   */
-  concatImapStringsSep = sep: f: list: concatStringsSep sep (lib.imap f list);
+  concatImapStringsSep = sep: f: list: concatStringsSep sep (lib.imap1 f list);
 
   /* Construct a Unix-style search path consisting of each `subDir"
      directory of the given list of packages.
diff --git a/lib/types.nix b/lib/types.nix
index 50aa6d7708528..a7dcd3f1e1c77 100644
--- a/lib/types.nix
+++ b/lib/types.nix
@@ -179,9 +179,9 @@ rec {
       description = "list of ${elemType.description}s";
       check = isList;
       merge = loc: defs:
-        map (x: x.value) (filter (x: x ? value) (concatLists (imap (n: def:
+        map (x: x.value) (filter (x: x ? value) (concatLists (imap1 (n: def:
           if isList def.value then
-            imap (m: def':
+            imap1 (m: def':
               (mergeDefinitions
                 (loc ++ ["[definition ${toString n}-entry ${toString m}]"])
                 elemType
@@ -220,7 +220,7 @@ rec {
           if isList def.value then
             { inherit (def) file;
               value = listToAttrs (
-                imap (elemIdx: elem:
+                imap1 (elemIdx: elem:
                   { name = elem.name or "unnamed-${toString defIdx}.${toString elemIdx}";
                     value = elem;
                   }) def.value);
@@ -233,7 +233,7 @@ rec {
         name = "loaOf";
         description = "list or attribute set of ${elemType.description}s";
         check = x: isList x || isAttrs x;
-        merge = loc: defs: attrOnly.merge loc (imap convertIfList defs);
+        merge = loc: defs: attrOnly.merge loc (imap1 convertIfList defs);
         getSubOptions = prefix: elemType.getSubOptions (prefix ++ ["<name?>"]);
         getSubModules = elemType.getSubModules;
         substSubModules = m: loaOf (elemType.substSubModules m);
diff --git a/nixos/modules/misc/meta.nix b/nixos/modules/misc/meta.nix
index 6a5738e47ff35..7a1e751394c0a 100644
--- a/nixos/modules/misc/meta.nix
+++ b/nixos/modules/misc/meta.nix
@@ -17,7 +17,7 @@ let
     #   }
     merge = loc: defs:
       zipAttrs
-        (flatten (imap (n: def: imap (m: def':
+        (flatten (imap1 (n: def: imap1 (m: def':
           maintainer.merge (loc ++ ["[${toString n}-${toString m}]"])
             [{ inherit (def) file; value = def'; }]) def.value) defs));
   };
diff --git a/nixos/modules/services/cluster/kubernetes.nix b/nixos/modules/services/cluster/kubernetes.nix
index 68917af5094c8..4c9d9aad0e2dc 100644
--- a/nixos/modules/services/cluster/kubernetes.nix
+++ b/nixos/modules/services/cluster/kubernetes.nix
@@ -44,7 +44,7 @@ let
 
   cniConfig = pkgs.buildEnv {
     name = "kubernetes-cni-config";
-    paths = imap (i: entry:
+    paths = imap1 (i: entry:
       pkgs.writeTextDir "${toString (10+i)}-${entry.type}.conf" (builtins.toJSON entry)
     ) cfg.kubelet.cni.config;
   };
diff --git a/nixos/modules/services/networking/libreswan.nix b/nixos/modules/services/networking/libreswan.nix
index c87e738d2a239..e7a6c565f4ff1 100644
--- a/nixos/modules/services/networking/libreswan.nix
+++ b/nixos/modules/services/networking/libreswan.nix
@@ -11,7 +11,7 @@ let
 
   trim = chars: str: let
       nonchars = filter (x : !(elem x.value chars))
-                  (imap (i: v: {ind = (sub i 1); value = v;}) (stringToCharacters str));
+                  (imap0 (i: v: {ind = i; value = v;}) (stringToCharacters str));
     in
       if length nonchars == 0 then ""
       else substring (head nonchars).ind (add 1 (sub (last nonchars).ind (head nonchars).ind)) str;
diff --git a/nixos/modules/services/networking/networkmanager.nix b/nixos/modules/services/networking/networkmanager.nix
index 58c93d8e2ac3e..f1b3d298fecb9 100644
--- a/nixos/modules/services/networking/networkmanager.nix
+++ b/nixos/modules/services/networking/networkmanager.nix
@@ -253,7 +253,7 @@ in {
            { source = overrideNameserversScript;
              target = "NetworkManager/dispatcher.d/02overridedns";
            }
-      ++ lib.imap (i: s: {
+      ++ lib.imap1 (i: s: {
         inherit (s) source;
         target = "NetworkManager/dispatcher.d/${dispatcherTypesSubdirMap.${s.type}}03userscript${lib.fixedWidthNumber 4 i}";
       }) cfg.dispatcherScripts;
diff --git a/nixos/modules/services/x11/xserver.nix b/nixos/modules/services/x11/xserver.nix
index bb9704fc26f01..638509e710be8 100644
--- a/nixos/modules/services/x11/xserver.nix
+++ b/nixos/modules/services/x11/xserver.nix
@@ -71,7 +71,7 @@ let
       name = "multihead${toString num}";
       inherit config;
     };
-  in imap mkHead cfg.xrandrHeads;
+  in imap1 mkHead cfg.xrandrHeads;
 
   xrandrDeviceSection = let
     monitors = flip map xrandrHeads (h: ''
diff --git a/pkgs/games/uqm/default.nix b/pkgs/games/uqm/default.nix
index d6bcb787d60c0..d1416b0685a7d 100644
--- a/pkgs/games/uqm/default.nix
+++ b/pkgs/games/uqm/default.nix
@@ -18,7 +18,7 @@ let
     inherit stdenv requireFile writeText fetchurl haskellPackages;
   };
 
-  remixPacks = imap (num: sha256: fetchurl rec {
+  remixPacks = imap1 (num: sha256: fetchurl rec {
     name = "uqm-remix-disc${toString num}.uqm";
     url = "mirror://sourceforge/sc2/${name}";
     inherit sha256;