Merge commit staging+systemd into closure-size

Many non-conflict problems weren't (fully) resolved in this commit yet.

lib/attrsets.nix

@@ -6,7 +6,6 @@ with {
   inherit (import ./default.nix) fold;
   inherit (import ./strings.nix) concatStringsSep;
   inherit (import ./lists.nix) concatMap concatLists all deepSeqList;
-  inherit (import ./misc.nix) maybeAttr;
 };
 
 rec {
@@ -76,9 +75,29 @@ rec {
        => { foo = 1; }
   */
   filterAttrs = pred: set:
-    listToAttrs (fold (n: ys: let v = set.${n}; in if pred n v then [(nameValuePair n v)] ++ ys else ys) [] (attrNames set));
+    listToAttrs (concatMap (name: let v = set.${name}; in if pred name v then [(nameValuePair name v)] else []) (attrNames set));
 
 
+  /* Filter an attribute set recursivelly by removing all attributes for
+     which the given predicate return false.
+
+     Example:
+       filterAttrsRecursive (n: v: v != null) { foo = { bar = null; }; }
+       => { foo = {}; }
+  */
+  filterAttrsRecursive = pred: set:
+    listToAttrs (
+      concatMap (name:
+        let v = set.${name}; in
+        if pred name v then [
+          (nameValuePair name (
+            if isAttrs v then filterAttrsRecursive pred v
+            else v
+          ))
+        ] else []
+      ) (attrNames set)
+    );
+
   /* foldAttrs: apply fold functions to values grouped by key. Eg accumulate values as list:
      foldAttrs (n: a: [n] ++ a) [] [{ a = 2; } { a = 3; }]
      => { a = [ 2 3 ]; }
@@ -86,7 +105,7 @@ rec {
   foldAttrs = op: nul: list_of_attrs:
     fold (n: a:
         fold (name: o:
-          o // (listToAttrs [{inherit name; value = op n.${name} (maybeAttr name nul a); }])
+          o // (listToAttrs [{inherit name; value = op n.${name} (a.${name} or nul); }])
         ) a (attrNames n)
     ) {} list_of_attrs;
 
@@ -222,6 +241,16 @@ rec {
   isDerivation = x: isAttrs x && x ? type && x.type == "derivation";
 
 
+  /* Convert a store path to a fake derivation. */
+  toDerivation = path:
+    let path' = builtins.storePath path; in
+    { type = "derivation";
+      name = builtins.unsafeDiscardStringContext (builtins.substring 33 (-1) (baseNameOf path'));
+      outPath = path';
+      outputs = [ "out" ];
+    };
+
+
   /* If the Boolean `cond' is true, return the attribute set `as',
      otherwise an empty attribute set. */
   optionalAttrs = cond: as: if cond then as else {};

lib/customisation.nix

@@ -1,6 +1,8 @@
 let
+
   lib = import ./default.nix;
   inherit (builtins) attrNames isFunction;
+
 in
 
 rec {
@@ -49,10 +51,6 @@ rec {
        else { }));
 
 
-  # usage: (you can use override multiple times)
-  # let d = makeOverridable stdenv.mkDerivation { name = ..; buildInputs; }
-  #     noBuildInputs = d.override { buildInputs = []; }
-  #     additionalBuildInputs = d.override ( args : args // { buildInputs = args.buildInputs ++ [ additional ]; } )
   makeOverridable = f: origArgs:
     let
       ff = f origArgs;
@@ -60,24 +58,16 @@ rec {
     in
       if builtins.isAttrs ff then (ff //
         { override = newArgs: makeOverridable f (overrideWith newArgs);
-          deepOverride = newArgs:
-            makeOverridable f (lib.overrideExisting (lib.mapAttrs (deepOverrider newArgs) origArgs) newArgs);
           overrideDerivation = fdrv:
             makeOverridable (args: overrideDerivation (f args) fdrv) origArgs;
         })
       else if builtins.isFunction ff then
         { override = newArgs: makeOverridable f (overrideWith newArgs);
           __functor = self: ff;
-          deepOverride = throw "deepOverride not yet supported for functors";
           overrideDerivation = throw "overrideDerivation not yet supported for functors";
         }
       else ff;
 
-  deepOverrider = newArgs: name: x: if builtins.isAttrs x then (
-    if x ? deepOverride then (x.deepOverride newArgs) else
-    if x ? override then (x.override newArgs) else
-    x) else x;
-
 
   /* Call the package function in the file `fn' with the required
     arguments automatically.  The function is called with the
@@ -102,12 +92,28 @@ rec {
   */
   callPackageWith = autoArgs: fn: args:
     let
-      f    = if builtins.isFunction fn then fn else import fn;
+      f = if builtins.isFunction fn then fn else import fn;
       auto = builtins.intersectAttrs (builtins.functionArgs f) autoArgs;
     in makeOverridable f (auto // args);
 
 
-  /* Add attributes to each output of a derivation without changing the derivation itself */
+  /* Like callPackage, but for a function that returns an attribute
+     set of derivations. The override function is added to the
+     individual attributes. */
+  callPackagesWith = autoArgs: fn: args:
+    let
+      f = if builtins.isFunction fn then fn else import fn;
+      auto = builtins.intersectAttrs (builtins.functionArgs f) autoArgs;
+      finalArgs = auto // args;
+      pkgs = f finalArgs;
+      mkAttrOverridable = name: pkg: pkg // {
+        override = newArgs: mkAttrOverridable name (f (finalArgs // newArgs)).${name};
+      };
+    in lib.mapAttrs mkAttrOverridable pkgs;
+
+
+  /* Add attributes to each output of a derivation without changing
+     the derivation itself. */
   addPassthru = drv: passthru:
     let
       outputs = drv.outputs or [ "out" ];
@@ -158,4 +164,23 @@ rec {
       drv' = (lib.head outputsList).value;
     in lib.deepSeq drv' drv';
 
+  /* Make a set of packages with a common scope. All packages called
+     with the provided `callPackage' will be evaluated with the same
+     arguments. Any package in the set may depend on any other. The
+     `override' function allows subsequent modification of the package
+     set in a consistent way, i.e. all packages in the set will be
+     called with the overridden packages. The package sets may be
+     hierarchical: the packages in the set are called with the scope
+     provided by `newScope' and the set provides a `newScope' attribute
+     which can form the parent scope for later package sets. */
+  makeScope = newScope: f:
+    let self = f self // {
+          newScope = scope: newScope (self // scope);
+          callPackage = self.newScope {};
+          override = g: makeScope newScope (self_:
+            let super = f self_;
+            in super // g super self_);
+        };
+    in self;
+
 }

lib/default.nix

@@ -11,7 +11,7 @@ let
   types = import ./types.nix;
   meta = import ./meta.nix;
   debug = import ./debug.nix;
-  misc = import ./misc.nix;
+  misc = import ./deprecated.nix;
   maintainers = import ./maintainers.nix;
   platforms = import ./platforms.nix;
   systems = import ./systems.nix;

lib/deprecated.nix

@@ -29,7 +29,6 @@ rec {
                           } ));
 	withStdOverrides = base // {
 	   override = base.passthru.function;
-	   deepOverride = a : (base.passthru.function ((lib.mapAttrs (lib.deepOverrider a) base.passthru.args) // a));
 	   } ;
         in
 	withStdOverrides;
@@ -203,8 +202,6 @@ rec {
     in
       work startSet [] [];
 
-  genericClosure = builtins.genericClosure or lazyGenericClosure;
-
   innerModifySumArgs = f: x: a: b: if b == null then (f a b) // x else 
         innerModifySumArgs f x (a // b);
   modifySumArgs = f: x: innerModifySumArgs f x {};

lib/licenses.nix

@@ -85,6 +85,11 @@ lib.mapAttrs (n: v: v // { shortName = n; }) rec {
     fullName = "Creative Commons Zero v1.0 Universal";
   };
 
+  cc-by-sa-25 = spdx {
+    spdxId = "CC-BY-SA-2.5";
+    fullName = "Creative Commons Attribution Share Alike 2.5";
+  };
+
   cc-by-30 = spdx {
     spdxId = "CC-BY-3.0";
     fullName = "Creative Commons Attribution 3.0";
@@ -150,6 +155,11 @@ lib.mapAttrs (n: v: v // { shortName = n; }) rec {
     fullName = "GNU Free Documentation License v1.2";
   };
 
+  fdl13 = spdx {
+    spdxId = "GFDL-1.3";
+    fullName = "GNU Free Documentation License v1.2";
+  };
+
   free = {
     fullName = "Unspecified free software license";
   };
@@ -322,11 +332,21 @@ lib.mapAttrs (n: v: v // { shortName = n; }) rec {
     fullName  = "University of Illinois/NCSA Open Source License";
   };
 
+  notion_lgpl = {
+    url = "https://raw.githubusercontent.com/raboof/notion/master/LICENSE";
+    fullName = "Notion modified LGPL";
+  };
+  
   ofl = spdx {
     spdxId = "OFL-1.1";
     fullName = "SIL Open Font License 1.1";
   };
 
+  openldap = spdx {
+    spdxId = "OLDAP-2.8";
+    fullName = "Open LDAP Public License v2.8";
+  };
+
   openssl = spdx {
     spdxId = "OpenSSL";
     fullName = "OpenSSL License";
@@ -403,6 +423,11 @@ lib.mapAttrs (n: v: v // { shortName = n; }) rec {
     fullName = "The Unlicense";
   };
 
+  vim = spdx {
+    spdxId = "Vim";
+    fullName = "Vim License";
+  };
+
   vsl10 = spdx {
     spdxId = "VSL-1.0";
     fullName = "Vovida Software License v1.0";

lib/lists.nix

@@ -4,7 +4,7 @@ with import ./trivial.nix;
 
 rec {
 
-  inherit (builtins) head tail length isList elemAt concatLists filter elem;
+  inherit (builtins) head tail length isList elemAt concatLists filter elem genList;
 
 
   # Create a list consisting of a single element.  `singleton x' is
@@ -38,16 +38,24 @@ rec {
     in foldl' (length list - 1);
 
 
-  # map with index: `imap (i: v: "${v}-${toString i}") ["a" "b"] ==
-  # ["a-1" "b-2"]'
-  imap = f: list:
-    let
-      len = length list;
-      imap' = n:
-        if n == len
-          then []
-          else [ (f (n + 1) (elemAt list n)) ] ++ imap' (n + 1);
-    in imap' 0;
+  # Strict version of foldl.
+  foldl' = builtins.foldl' or foldl;
+
+
+  # Map with index: `imap (i: v: "${v}-${toString i}") ["a" "b"] ==
+  # ["a-1" "b-2"]'. FIXME: why does this start to count at 1?
+  imap =
+    if builtins ? genList then
+      f: list: genList (n: f (n + 1) (elemAt list n)) (length list)
+    else
+      f: list:
+      let
+        len = length list;
+        imap' = n:
+          if n == len
+            then []
+            else [ (f (n + 1) (elemAt list n)) ] ++ imap' (n + 1);
+      in imap' 0;
 
 
   # Map and concatenate the result.
@@ -59,7 +67,7 @@ rec {
   # == [1 2 3 4 5]' and `flatten 1 == [1]'.
   flatten = x:
     if isList x
-    then fold (x: y: (flatten x) ++ y) [] x
+    then foldl' (x: y: x ++ (flatten y)) [] x
     else [x];
 
 
@@ -86,17 +94,17 @@ rec {
 
   # Return true iff function `pred' returns true for at least element
   # of `list'.
-  any = pred: fold (x: y: if pred x then true else y) false;
+  any = builtins.any or (pred: fold (x: y: if pred x then true else y) false);
 
 
   # Return true iff function `pred' returns true for all elements of
   # `list'.
-  all = pred: fold (x: y: if pred x then y else false) true;
+  all = builtins.all or (pred: fold (x: y: if pred x then y else false) true);
 
 
   # Count how many times function `pred' returns true for the elements
   # of `list'.
-  count = pred: fold (x: c: if pred x then c + 1 else c) 0;
+  count = pred: foldl' (c: x: if pred x then c + 1 else c) 0;
 
 
   # Return a singleton list or an empty list, depending on a boolean
@@ -116,10 +124,17 @@ rec {
 
 
   # Return a list of integers from `first' up to and including `last'.
-  range = first: last:
-    if last < first
-    then []
-    else [first] ++ range (first + 1) last;
+  range =
+    if builtins ? genList then
+      first: last:
+        if first > last
+        then []
+        else genList (n: first + n) (last - first + 1)
+    else
+      first: last:
+        if last < first
+        then []
+        else [first] ++ range (first + 1) last;
 
 
   # Partition the elements of a list in two lists, `right' and
@@ -132,30 +147,37 @@ rec {
     ) { right = []; wrong = []; };
 
 
-  zipListsWith = f: fst: snd:
-    let
-      len1 = length fst;
-      len2 = length snd;
-      len = if len1 < len2 then len1 else len2;
-      zipListsWith' = n:
-        if n != len then
-          [ (f (elemAt fst n) (elemAt snd n)) ]
-          ++ zipListsWith' (n + 1)
-        else [];
-    in zipListsWith' 0;
+  zipListsWith =
+    if builtins ? genList then
+      f: fst: snd: genList (n: f (elemAt fst n) (elemAt snd n)) (min (length fst) (length snd))
+    else
+      f: fst: snd:
+      let
+        len = min (length fst) (length snd);
+        zipListsWith' = n:
+          if n != len then
+            [ (f (elemAt fst n) (elemAt snd n)) ]
+            ++ zipListsWith' (n + 1)
+          else [];
+      in zipListsWith' 0;
 
   zipLists = zipListsWith (fst: snd: { inherit fst snd; });
 
 
-  # Reverse the order of the elements of a list.  FIXME: O(n^2)!
-  reverseList = fold (e: acc: acc ++ [ e ]) [];
+  # Reverse the order of the elements of a list.
+  reverseList =
+    if builtins ? genList then
+      xs: let l = length xs; in genList (n: elemAt xs (l - n - 1)) l
+    else
+      fold (e: acc: acc ++ [ e ]) [];
 
 
   # Sort a list based on a comparator function which compares two
   # elements and returns true if the first argument is strictly below
   # the second argument.  The returned list is sorted in an increasing
   # order.  The implementation does a quick-sort.
-  sort = strictLess: list:
+  sort = builtins.sort or (
+    strictLess: list:
     let
       len = length list;
       first = head list;
@@ -169,31 +191,50 @@ rec {
       pivot = pivot' 1 { left = []; right = []; };
     in
       if len < 2 then list
-      else (sort strictLess pivot.left) ++  [ first ] ++  (sort strictLess pivot.right);
+      else (sort strictLess pivot.left) ++  [ first ] ++  (sort strictLess pivot.right));
 
 
   # Return the first (at most) N elements of a list.
-  take = count: list:
-    let
-      len = length list;
-      take' = n:
-        if n == len || n == count
-          then []
-        else
-          [ (elemAt list n) ] ++ take' (n + 1);
-    in take' 0;
+  take =
+    if builtins ? genList then
+      count: sublist 0 count
+    else
+      count: list:
+        let
+          len = length list;
+          take' = n:
+            if n == len || n == count
+              then []
+            else
+              [ (elemAt list n) ] ++ take' (n + 1);
+        in take' 0;
 
 
   # Remove the first (at most) N elements of a list.
-  drop = count: list:
-    let
-      len = length list;
-      drop' = n:
-        if n == -1 || n < count
-          then []
-        else
-          drop' (n - 1) ++ [ (elemAt list n) ];
-    in drop' (len - 1);
+  drop =
+    if builtins ? genList then
+      count: list: sublist count (length list) list
+    else
+      count: list:
+        let
+          len = length list;
+          drop' = n:
+            if n == -1 || n < count
+              then []
+            else
+              drop' (n - 1) ++ [ (elemAt list n) ];
+        in drop' (len - 1);
+
+
+  # Return a list consisting of at most ‘count’ elements of ‘list’,
+  # starting at index ‘start’.
+  sublist = start: count: list:
+    let len = length list; in
+    genList
+      (n: elemAt list (n + start))
+      (if start >= len then 0
+       else if start + count > len then len - start
+       else count);
 
 
   # Return the last element of a list.
@@ -205,25 +246,13 @@ rec {
   init = list: assert list != []; take (length list - 1) list;
 
 
-  # Zip two lists together.
-  zipTwoLists = xs: ys:
-    let
-      len1 = length xs;
-      len2 = length ys;
-      len = if len1 < len2 then len1 else len2;
-      zipTwoLists' = n:
-        if n != len then
-          [ { first = elemAt xs n; second = elemAt ys n; } ]
-          ++ zipTwoLists' (n + 1)
-        else [];
-    in zipTwoLists' 0;
-
-
   deepSeqList = xs: y: if any (x: deepSeq x false) xs then y else y;
 
+
   crossLists = f: foldl (fs: args: concatMap (f: map f args) fs) [f];
 
-  # Remove duplicate elements from the list
+
+  # Remove duplicate elements from the list. O(n^2) complexity.
   unique = list:
     if list == [] then
       []
@@ -233,9 +262,12 @@ rec {
         xs = unique (drop 1 list);
       in [x] ++ remove x xs;
 
-  # Intersects list 'e' and another list
+
+  # Intersects list 'e' and another list. O(nm) complexity.
   intersectLists = e: filter (x: elem x e);
 
-  # Subtracts list 'e' from another list
+
+  # Subtracts list 'e' from another list. O(nm) complexity.
   subtractLists = e: filter (x: !(elem x e));
+
 }

lib/maintainers.nix

@@ -1,22 +1,31 @@
 /* -*- coding: utf-8; -*- */
 
 {
-  /* Add your name and email address here.  Keep the list
-     alphabetically sorted.  */
+  /* Add your name and email address here.
+     Keep the list alphabetically sorted.
+     Prefer the same attrname as your github username, please,
+     so it's easy to ping a package @maintainer.
+  */
 
-  _1126 = "Christian Lask <mail@elfsechsundzwanzig.de>";
+  a1russell = "Adam Russell <adamlr6+pub@gmail.com>";
   abaldeau = "Andreas Baldeau <andreas@baldeau.net>";
   abbradar = "Nikolay Amiantov <ab@fmap.me>";
+  adev	   = "Adrien Devresse <adev@adev.name>";
   aforemny = "Alexander Foremny <alexanderforemny@googlemail.com>";
+  aflatter = "Alexander Flatter <flatter@fastmail.fm>";
   aherrmann = "Andreas Herrmann <andreash87@gmx.ch>";
   ak = "Alexander Kjeldaas <ak@formalprivacy.com>";
+  akaWolf = "Artjom Vejsel <akawolf0@gmail.com>";
   akc = "Anders Claesson <akc@akc.is>";
   algorith = "Dries Van Daele <dries_van_daele@telenet.be>";
   all = "Nix Committers <nix-commits@lists.science.uu.nl>";
+  ambrop72 = "Ambroz Bizjak <ambrop7@gmail.com>";
   amiddelk = "Arie Middelkoop <amiddelk@gmail.com>";
   amorsillo = "Andrew Morsillo <andrew.morsillo@gmail.com>";
   AndersonTorres = "Anderson Torres <torres.anderson.85@gmail.com>";
+  anderspapitto = "Anders Papitto <anderspapitto@gmail.com>";
   andres = "Andres Loeh <ksnixos@andres-loeh.de>";
+  andrewrk = "Andrew Kelley <superjoe30@gmail.com>";
   antono = "Antono Vasiljev <self@antono.info>";
   ardumont = "Antoine R. Dumont <eniotna.t@gmail.com>";
   aristid = "Aristid Breitkreuz <aristidb@gmail.com>";
@@ -25,9 +34,12 @@
   astsmtl = "Alexander Tsamutali <astsmtl@yandex.ru>";
   aszlig = "aszlig <aszlig@redmoonstudios.org>";
   auntie = "Jonathan Glines <auntieNeo@gmail.com>";
+  avnik = "Alexander V. Nikolaev <avn@avnik.info>";
   aycanirican = "Aycan iRiCAN <iricanaycan@gmail.com>";
+  badi = "Badi' Abdul-Wahid <abdulwahidc@gmail.com>";
   balajisivaraman = "Balaji Sivaraman<sivaraman.balaji@gmail.com>";
   bbenoist = "Baptist BENOIST <return_0@live.com>";
+  bcarrell = "Brandon Carrell <brandoncarrell@gmail.com>";
   bcdarwin = "Ben Darwin <bcdarwin@gmail.com>";
   bdimcheff = "Brandon Dimcheff <brandon@dimcheff.com>";
   bennofs = "Benno Fünfstück <benno.fuenfstueck@gmail.com>";
@@ -41,27 +53,36 @@
   bodil = "Bodil Stokke <nix@bodil.org>";
   boothead = "Ben Ford <ben@perurbis.com>";
   bosu = "Boris Sukholitko <boriss@gmail.com>";
+  bramd = "Bram Duvigneau <bram@bramd.nl>";
   bstrik = "Berno Strik <dutchman55@gmx.com>";
+  c0dehero = "CodeHero <codehero@nerdpol.ch>";
   calrama = "Moritz Maxeiner <moritz@ucworks.org>";
   campadrenalin = "Philip Horger <campadrenalin@gmail.com>";
   cdepillabout = "Dennis Gosnell <cdep.illabout@gmail.com>";
   cfouche = "Chaddaï Fouché <chaddai.fouche@gmail.com>";
   chaoflow = "Florian Friesdorf <flo@chaoflow.net>";
+  chattered = "Phil Scott <me@philscotted.com>";
   christopherpoole = "Christopher Mark Poole <mail@christopherpoole.net>";
   coconnor = "Corey O'Connor <coreyoconnor@gmail.com>";
   codyopel = "Cody Opel <codyopel@gmail.com>";
   copumpkin = "Dan Peebles <pumpkingod@gmail.com>";
   coroa = "Jonas Hörsch <jonas@chaoflow.net>";
+  couchemar = "Andrey Pavlov <couchemar@yandex.ru>";
   cstrahan = "Charles Strahan <charles.c.strahan@gmail.com>";
   cwoac = "Oliver Matthews <oliver@codersoffortune.net>";
-  DamienCassou = "Damien Cassou <damien.cassou@gmail.com>";
+  DamienCassou = "Damien Cassou <damien@cassou.me>";
+  davidak = "David Kleuker <post@davidak.de>";
   davidrusu = "David Rusu <davidrusu.me@gmail.com>";
   dbohdan = "Danyil Bohdan <danyil.bohdan@gmail.com>";
   DerGuteMoritz = "Moritz Heidkamp <moritz@twoticketsplease.de>";
+  deepfire = "Kosyrev Serge <_deepfire@feelingofgreen.ru>";
+  desiderius = "Didier J. Devroye <didier@devroye.name>";
   devhell = "devhell <\"^\"@regexmail.net>";
   dezgeg = "Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>";
+  dfoxfranke = "Daniel Fox Franke <dfoxfranke@gmail.com>";
   dmalikov = "Dmitry Malikov <malikov.d.y@gmail.com>";
   doublec = "Chris Double <chris.double@double.co.nz>";
+  ebzzry = "Rommel Martinez <ebzzry@gmail.com>";
   ederoyd46 = "Matthew Brown <matt@ederoyd.co.uk>";
   eduarrrd = "Eduard Bachmakov <e.bachmakov@gmail.com>";
   edwtjo = "Edward Tjörnhammar <ed@cflags.cc>";
@@ -69,6 +90,9 @@
   eikek = "Eike Kettner <eike.kettner@posteo.de>";
   ellis = "Ellis Whitehead <nixos@ellisw.net>";
   emery = "Emery Hemingway <emery@vfemail.net>";
+  epitrochoid = "Mabry Cervin <mpcervin@uncg.edu>";
+  ericbmerritt = "Eric Merritt <eric@afiniate.com>";
+  erikryb = "Erik Rybakken <erik.rybakken@math.ntnu.no>";
   ertes = "Ertugrul Söylemez <ertesx@gmx.de>";
   exlevan = "Alexey Levan <exlevan@gmail.com>";
   falsifian = "James Cook <james.cook@utoronto.ca>";
@@ -76,6 +100,8 @@
   fluffynukeit = "Daniel Austin <dan@fluffynukeit.com>";
   forkk = "Andrew Okin <forkk@forkk.net>";
   fpletz = "Franz Pletz <fpletz@fnordicwalking.de>";
+  fridh = "Frederik Rietdijk <fridh@fridh.nl>";
+  fro_ozen = "fro_ozen <fro_ozen@gmx.de>";
   ftrvxmtrx = "Siarhei Zirukin <ftrvxmtrx@gmail.com>";
   funfunctor = "Edward O'Callaghan <eocallaghan@alterapraxis.com>";
   fuuzetsu = "Mateusz Kowalczyk <fuuzetsu@fuuzetsu.co.uk>";
@@ -84,23 +110,29 @@
   garrison = "Jim Garrison <jim@garrison.cc>";
   gavin = "Gavin Rogers <gavin@praxeology.co.uk>";
   gebner = "Gabriel Ebner <gebner@gebner.org>";
+  gfxmonk = "Tim Cuthbertson <tim@gfxmonk.net>";
   giogadi = "Luis G. Torres <lgtorres42@gmail.com>";
   globin = "Robin Gloster <robin@glob.in>";
   goibhniu = "Cillian de Róiste <cillian.deroiste@gmail.com>";
   gridaphobe = "Eric Seidel <eric@seidel.io>";
   guibert = "David Guibert <david.guibert@gmail.com>";
+  havvy = "Ryan Scheel <ryan.havvy@gmail.com>";
   hbunke = "Hendrik Bunke <bunke.hendrik@gmail.com>";
   henrytill = "Henry Till <henrytill@gmail.com>";
+  hiberno = "Christian Lask <mail@elfsechsundzwanzig.de>";
   hinton = "Tom Hinton <t@larkery.com>";
   hrdinka = "Christoph Hrdinka <c.nix@hrdinka.at>";
   iand675 = "Ian Duncan <ian@iankduncan.com>";
   ianwookim = "Ian-Woo Kim <ianwookim@gmail.com>";
   iElectric = "Domen Kozar <domen@dev.si>";
+  ikervagyok = "Balázs Lengyel <ikervagyok@gmail.com>";
   iyzsong = "Song Wenwu <iyzsong@gmail.com>";
   j-keck = "Jürgen Keck <jhyphenkeck@gmail.com>";
   jagajaga = "Arseniy Seroka <ars.seroka@gmail.com>";
   jb55 = "William Casarin <bill@casarin.me>";
   jcumming = "Jack Cummings <jack@mudshark.org>";
+  jefdaj = "Jeffrey David Johnson <jefdaj@gmail.com>";
+  jfb = "James Felix Black <james@yamtime.com>";
   jgeerds = "Jascha Geerds <jg@ekby.de>";
   jirkamarsik = "Jirka Marsik <jiri.marsik89@gmail.com>";
   joachifm = "Joachim Fasting <joachifm@fastmail.fm>";
@@ -109,33 +141,52 @@
   joelteon = "Joel Taylor <me@joelt.io>";
   jpbernardy = "Jean-Philippe Bernardy <jeanphilippe.bernardy@gmail.com>";
   jwiegley = "John Wiegley <johnw@newartisans.com>";
+  jwilberding = "Jordan Wilberding <jwilberding@afiniate.com>";
   jzellner = "Jeff Zellner <jeffz@eml.cc>";
+  kamilchm = "Kamil Chmielewski <kamil.chm@gmail.com>";
+  khumba = "Bryan Gardiner <bog@khumba.net>";
   kkallio = "Karn Kallio <tierpluspluslists@gmail.com>";
   koral = "Koral <koral@mailoo.org>";
   kovirobi = "Kovacsics Robert <kovirobi@gmail.com>";
   kragniz = "Louis Taylor <kragniz@gmail.com>";
   ktosiek = "Tomasz Kontusz <tomasz.kontusz@gmail.com>";
+  lassulus = "Lassulus <lassulus@gmail.com>";
+  layus = "Guillaume Maudoux <layus.on@gmail.com>";
+  lebastr = "Alexander Lebedev <lebastr@gmail.com>";
+  leonardoce = "Leonardo Cecchi <leonardo.cecchi@gmail.com>";
   lethalman = "Luca Bruno <lucabru@src.gnome.org>";
   lhvwb = "Nathaniel Baxter <nathaniel.baxter@gmail.com>";
+  lihop = "Leroy Hopson <nixos@leroy.geek.nz>";
   linquize = "Linquize <linquize@yahoo.com.hk>";
   linus = "Linus Arver <linusarver@gmail.com>";
+  lnl7 = "Daiderd Jordan <daiderd@gmail.com>";
   lovek323 = "Jason O'Conal <jason@oconal.id.au>";
+  lowfatcomputing = "Andreas Wagner <andreas.wagner@lowfatcomputing.org>";
+  lsix = "Lancelot SIX <lsix@lancelotsix.com>";
   ludo = "Ludovic Courtès <ludo@gnu.org>";
   madjar = "Georges Dubus <georges.dubus@compiletoi.net>";
   magnetophon = "Bart Brouns <bart@magnetophon.nl>";
+  mahe = "Matthias Herrmann <matthias.mh.herrmann@gmail.com>";
+  makefu = "Felix Richter <makefu@syntax-fehler.de>";
   malyn = "Michael Alyn Miller <malyn@strangeGizmo.com>";
   manveru = "Michael Fellinger <m.fellinger@gmail.com>";
   marcweber = "Marc Weber <marco-oweber@gmx.de>";
+  maurer = "Matthew Maurer <matthew.r.maurer+nix@gmail.com>";
   matejc = "Matej Cotman <cotman.matej@gmail.com>";
+  mathnerd314 = "Mathnerd314 <mathnerd314.gph+hs@gmail.com>";
   matthiasbeyer = "Matthias Beyer <mail@beyermatthias.de>";
+  mbakke = "Marius Bakke <ymse@tuta.io>";
   meditans = "Carlo Nucera <meditans@gmail.com>";
   meisternu = "Matt Miemiec <meister@krutt.org>";
   michelk = "Michel Kuhlmann <michel@kuhlmanns.info>";
+  mirdhyn = "Merlin Gaillard <mirdhyn@gmail.com>";
+  mschristiansen = "Mikkel Christiansen <mikkel@rheosystems.com>";
   modulistic = "Pablo Costa <modulistic@gmail.com>";
   mornfall = "Petr Ročkai <me@mornfall.net>";
   MP2E = "Cray Elliott <MP2E@archlinux.us>";
   msackman = "Matthew Sackman <matthew@wellquite.org>";
   mtreskin = "Max Treskin <zerthurd@gmail.com>";
+  mudri = "James Wood <lamudri@gmail.com>";
   muflax = "Stefan Dorn <mail@muflax.com>";
   nathan-gs = "Nathan Bijnens <nathan@nathan.gs>";
   nckx = "Tobias Geerinckx-Rice <tobias.geerinckx.rice@gmail.com>";
@@ -144,14 +195,18 @@
   nslqqq = "Nikita Mikhailov <nslqqq@gmail.com>";
   obadz = "obadz <dav-nixos@odav.org>";
   ocharles = "Oliver Charles <ollie@ocharles.org.uk>";
+  odi = "Oliver Dunkl <oliver.dunkl@gmail.com>";
   offline = "Jaka Hudoklin <jakahudoklin@gmail.com>";
   olcai = "Erik Timan <dev@timan.info>";
   orbitz = "Malcolm Matalka <mmatalka@gmail.com>";
+  osener = "Ozan Sener <ozan@ozansener.com>";
   page = "Carles Pagès <page@cubata.homelinux.net>";
   paholg = "Paho Lurie-Gregg <paho@paholg.com>";
   pakhfn = "Fedor Pakhomov <pakhfn@gmail.com>";
   pashev = "Igor Pashev <pashev.igor@gmail.com>";
+  pesterhazy = "Paulus Esterhazy <pesterhazy@gmail.com>";
   phausmann = "Philipp Hausmann <nix@314.ch>";
+  philandstuff = "Philip Potter <philip.g.potter@gmail.com>";
   phreedom = "Evgeny Egorochkin <phreedom@yandex.ru>";
   pierron = "Nicolas B. Pierron <nixos@nbp.name>";
   piotr = "Piotr Pietraszkiewicz <ppietrasa@gmail.com>";
@@ -159,7 +214,9 @@
   pkmx = "Chih-Mao Chen <pkmx.tw@gmail.com>";
   plcplc = "Philip Lykke Carlsen <plcplc@gmail.com>";
   pmahoney = "Patrick Mahoney <pat@polycrystal.org>";
+  pmiddend = "Philipp Middendorf <pmidden@secure.mailbox.org>";
   prikhi = "Pavan Rikhi <pavan.rikhi@gmail.com>";
+  psibi = "Sibi <sibi@psibi.in>";
   pSub = "Pascal Wittmann <mail@pascal-wittmann.de>";
   puffnfresh = "Brian McKenna <brian@brianmckenna.org>";
   qknight = "Joachim Schiele <js@lastlog.de>";
@@ -169,37 +226,47 @@
   refnil = "Martin Lavoie <broemartino@gmail.com>";
   relrod = "Ricky Elrod <ricky@elrod.me>";
   renzo = "Renzo Carbonara <renzocarbonara@gmail.com>";
+  rick68 = "Wei-Ming Yang <rick68@gmail.com>";
   rickynils = "Rickard Nilsson <rickynils@gmail.com>";
   rob = "Rob Vermaas <rob.vermaas@gmail.com>";
   robberer = "Longrin Wischnewski <robberer@freakmail.de>";
+  robbinch = "Robbin C. <robbinch33@gmail.com>";
   roconnor = "Russell O'Connor <roconnor@theorem.ca>";
   roelof = "Roelof Wobben <rwobben@hotmail.com>";
   romildo = "José Romildo Malaquias <malaquias@gmail.com>";
   rszibele = "Richard Szibele <richard_szibele@hotmail.com>";
   rushmorem = "Rushmore Mushambi <rushmore@webenchanter.com>";
   rycee = "Robert Helgesson <robert@rycee.net>";
+  samuelrivas = "Samuel Rivas <samuelrivas@gmail.com>";
   sander = "Sander van der Burg <s.vanderburg@tudelft.nl>";
   schmitthenner = "Fabian Schmitthenner <development@schmitthenner.eu>";
   schristo = "Scott Christopher <schristopher@konputa.com>";
   sepi = "Raffael Mancini <raffael@mancini.lu>";
+  sheganinans = "Aistis Raulinaitis <sheganinans@gmail.com>";
   shell = "Shell Turner <cam.turn@gmail.com>";
   shlevy = "Shea Levy <shea@shealevy.com>";
   simons = "Peter Simons <simons@cryp.to>";
+  simonvandel = "Simon Vandel Sillesen <simon.vandel@gmail.com>";
   sjagoe = "Simon Jagoe <simon@simonjagoe.com>";
   sjmackenzie = "Stewart Mackenzie <setori88@gmail.com>";
   skeidel = "Sven Keidel <svenkeidel@gmail.com>";
   smironov = "Sergey Mironov <ierton@gmail.com>";
+  spacefrogg = "Michael Raitza <spacefrogg-nixos@meterriblecrew.net>";
   sprock = "Roger Mason <rmason@mun.ca>";
   spwhitt = "Spencer Whitt <sw@swhitt.me>";
+  stephenmw = "Stephen Weinberg <stephen@q5comm.com>";
+  szczyp = "Szczyp <qb@szczyp.com>";
   sztupi = "Attila Sztupak <attila.sztupak@gmail.com>";
   tailhook = "Paul Colomiets <paul@colomiets.name>";
   taktoa = "Remy Goldschmidt <taktoa@gmail.com>";
+  telotortium = "Robert Irelan <rirelan@gmail.com>";
   thammers = "Tobias Hammerschmidt <jawr@gmx.de>";
   the-kenny = "Moritz Ulrich <moritz@tarn-vedra.de>";
   theuni = "Christian Theune <ct@flyingcircus.io>";
   thoughtpolice = "Austin Seipp <aseipp@pobox.com>";
   titanous = "Jonathan Rudenberg <jonathan@titanous.com>";
   tomberek = "Thomas Bereknyei <tomberek@gmail.com>";
+  travisbhartwell = "Travis B. Hartwell <nafai@travishartwell.net>";
   trino = "Hubert Mühlhans <muehlhans.hubert@ekodia.de>";
   tstrobel = "Thomas Strobel <ts468@cam.ac.uk>";
   ttuegel = "Thomas Tuegel <ttuegel@gmail.com>";
@@ -218,6 +285,7 @@
   winden = "Antonio Vargas Gonzalez <windenntw@gmail.com>";
   wizeman = "Ricardo M. Correia <rcorreia@wizy.org>";
   wjlroe = "William Roe <willroe@gmail.com>";
+  womfoo = "Kranium Gikos Mendoza <kranium@gikos.net>";
   wkennington = "William A. Kennington III <william@wkennington.com>";
   wmertens = "Wout Mertens <Wout.Mertens@gmail.com>";
   wscott = "Wayne Scott <wsc9tt@gmail.com>";

lib/modules.nix

@@ -17,6 +17,10 @@ rec {
      evalModules) and the less declarative the module set is. */
   evalModules = { modules
                 , prefix ? []
+                , # This should only be used for special arguments that need to be evaluated
+                  # when resolving module structure (like in imports). For everything else,
+                  # there's _module.args.
+                  specialArgs ? {}
                 , # This would be remove in the future, Prefer _module.args option instead.
                   args ? {}
                 , # This would be remove in the future, Prefer _module.check option instead.
@@ -39,7 +43,7 @@ rec {
           };
 
           _module.check = mkOption {
-            type = types.uniq types.bool;
+            type = types.bool;
             internal = true;
             default = check;
             description = "Whether to check whether all option definitions have matching declarations.";
@@ -51,7 +55,7 @@ rec {
         };
       };
 
-      closed = closeModules (modules ++ [ internalModule ]) { inherit config options; lib = import ./.; };
+      closed = closeModules (modules ++ [ internalModule ]) ({ inherit config options; lib = import ./.; } // specialArgs);
 
       # Note: the list of modules is reversed to maintain backward
       # compatibility with the old module system.  Not sure if this is
@@ -72,8 +76,8 @@ rec {
           else yieldConfig (prefix ++ [n]) v) set) ["_definedNames"];
         in
         if options._module.check.value && set ? _definedNames then
-          fold (m: res:
-            fold (name: res:
+          foldl' (res: m:
+            foldl' (res: name:
               if set ? ${name} then res else throw "The option `${showOption (prefix ++ [name])}' defined in `${m.file}' does not exist.")
               res m.names)
             res set._definedNames
@@ -87,9 +91,11 @@ rec {
     let
       toClosureList = file: parentKey: imap (n: x:
         if isAttrs x || isFunction x then
-          unifyModuleSyntax file "${parentKey}:anon-${toString n}" (unpackSubmodule applyIfFunction x args)
+          let key = "${parentKey}:anon-${toString n}"; in
+          unifyModuleSyntax file key (unpackSubmodule (applyIfFunction key) x args)
         else
-          unifyModuleSyntax (toString x) (toString x) (applyIfFunction (import x) args));
+          let file = toString x; key = toString x; in
+          unifyModuleSyntax file key (applyIfFunction key (import x) args));
     in
       builtins.genericClosure {
         startSet = toClosureList unknownModule "" modules;
@@ -118,7 +124,7 @@ rec {
         config = removeAttrs m ["key" "_file" "require" "imports"];
       };
 
-  applyIfFunction = f: arg@{ config, options, lib }: if isFunction f then
+  applyIfFunction = key: f: args@{ config, options, lib, ... }: if isFunction f then
     let
       # Module arguments are resolved in a strict manner when attribute set
       # deconstruction is used.  As the arguments are now defined with the
@@ -133,11 +139,18 @@ rec {
       # not their values.  The values are forwarding the result of the
       # evaluation of the option.
       requiredArgs = builtins.attrNames (builtins.functionArgs f);
+      context = name: ''while evaluating the module argument `${name}' in "${key}":'';
       extraArgs = builtins.listToAttrs (map (name: {
         inherit name;
-        value = config._module.args.${name};
+        value = addErrorContext (context name)
+          (args.${name} or config._module.args.${name});
       }) requiredArgs);
-    in f (extraArgs // arg)
+
+      # Note: we append in the opposite order such that we can add an error
+      # context on the explicited arguments of "args" too. This update
+      # operator is used to make the "args@{ ... }: with args.lib;" notation
+      # works.
+    in f (args // extraArgs)
   else
     f;
 
@@ -169,18 +182,18 @@ rec {
         let
           loc = prefix ++ [name];
           # Get all submodules that declare ‘name’.
-          decls = concatLists (map (m:
+          decls = concatMap (m:
             if m.options ? ${name}
               then [ { inherit (m) file; options = m.options.${name}; } ]
               else []
-            ) options);
+            ) options;
           # Get all submodules that define ‘name’.
-          defns = concatLists (map (m:
+          defns = concatMap (m:
             if m.config ? ${name}
               then map (config: { inherit (m) file; inherit config; })
                 (pushDownProperties m.config.${name})
               else []
-            ) configs);
+            ) configs;
           nrOptions = count (m: isOption m.options) decls;
           # Extract the definitions for this loc
           defns' = map (m: { inherit (m) file; value = m.config.${name}; })
@@ -212,7 +225,7 @@ rec {
      'opts' is a list of modules.  Each module has an options attribute which
      correspond to the definition of 'loc' in 'opt.file'. */
   mergeOptionDecls = loc: opts:
-    fold (opt: res:
+    foldl' (res: opt:
       if opt.options ? default && res ? default ||
          opt.options ? example && res ? example ||
          opt.options ? description && res ? description ||
@@ -238,7 +251,7 @@ rec {
             else if opt.options ? options then map (coerceOption opt.file) options' ++ res.options
             else res.options;
         in opt.options // res //
-          { declarations = [opt.file] ++ res.declarations;
+          { declarations = res.declarations ++ [opt.file];
             options = submodules;
           }
     ) { inherit loc; declarations = []; options = []; } opts;
@@ -248,58 +261,67 @@ rec {
   evalOptionValue = loc: opt: defs:
     let
       # Add in the default value for this option, if any.
-      defs' = (optional (opt ? default)
-        { file = head opt.declarations; value = mkOptionDefault opt.default; }) ++ defs;
+      defs' =
+          (optional (opt ? default)
+            { file = head opt.declarations; value = mkOptionDefault opt.default; }) ++ defs;
 
-      # Handle properties, check types, and merge everything together
-      inherit (mergeDefinitions loc opt.type defs') isDefined defsFinal mergedValue;
-      files = map (def: def.file) defsFinal;
-      merged =
-        if isDefined then mergedValue
-        else throw "The option `${showOption loc}' is used but not defined.";
+      # Handle properties, check types, and merge everything together.
+      res =
+        if opt.readOnly or false && length defs' > 1 then
+          throw "The option `${showOption loc}' is read-only, but it's set multiple times."
+        else
+          mergeDefinitions loc opt.type defs';
+
+      # Check whether the option is defined, and apply the ‘apply’
+      # function to the merged value.  This allows options to yield a
+      # value computed from the definitions.
+      value =
+        if !res.isDefined then
+          throw "The option `${showOption loc}' is used but not defined."
+        else if opt ? apply then
+          opt.apply res.mergedValue
+        else
+          res.mergedValue;
 
-      # Finally, apply the ‘apply’ function to the merged
-      # value.  This allows options to yield a value computed
-      # from the definitions.
-      value = (opt.apply or id) merged;
     in opt //
       { value = addErrorContext "while evaluating the option `${showOption loc}':" value;
-        definitions = map (def: def.value) defsFinal;
-        inherit isDefined files;
+        definitions = map (def: def.value) res.defsFinal;
+        files = map (def: def.file) res.defsFinal;
+        inherit (res) isDefined;
       };
 
-    # Merge definitions of a value of a given type
-    mergeDefinitions = loc: type: defs: rec {
-      defsFinal =
-        let
-          # Process mkMerge and mkIf properties
-          processIfAndMerge = defs: concatMap (m:
-            map (value: { inherit (m) file; inherit value; }) (dischargeProperties m.value)
-          ) defs;
+  # Merge definitions of a value of a given type.
+  mergeDefinitions = loc: type: defs: rec {
+    defsFinal =
+      let
+        # Process mkMerge and mkIf properties.
+        defs' = concatMap (m:
+          map (value: { inherit (m) file; inherit value; }) (dischargeProperties m.value)
+        ) defs;
 
-          # Process mkOverride properties
-          processOverride = defs: filterOverrides defs;
+        # Process mkOverride properties.
+        defs'' = filterOverrides defs';
 
-          # Sort mkOrder properties
-          processOrder = defs:
-            # Avoid sorting if we don't have to.
-            if any (def: def.value._type or "" == "order") defs
-            then sortProperties defs
-            else defs;
-        in
-          processOrder (processOverride (processIfAndMerge defs));
+        # Sort mkOrder properties.
+        defs''' =
+          # Avoid sorting if we don't have to.
+          if any (def: def.value._type or "" == "order") defs''
+          then sortProperties defs''
+          else defs'';
+      in defs''';
 
-        # Type-check the remaining definitions, and merge them
-        mergedValue = fold (def: res:
-          if type.check def.value then res
-          else throw "The option value `${showOption loc}' in `${def.file}' is not a ${type.name}.")
-          (type.merge loc defsFinal) defsFinal;
+    # Type-check the remaining definitions, and merge them.
+    mergedValue = foldl' (res: def:
+      if type.check def.value then res
+      else throw "The option value `${showOption loc}' in `${def.file}' is not a ${type.name}.")
+      (type.merge loc defsFinal) defsFinal;
 
-        isDefined = defsFinal != [];
-        optionalValue =
-          if isDefined then { value = mergedValue; }
-          else {};
-    };
+    isDefined = defsFinal != [];
+
+    optionalValue =
+      if isDefined then { value = mergedValue; }
+      else {};
+  };
 
   /* Given a config set, expand mkMerge properties, and push down the
      other properties into the children.  The result is a list of
@@ -370,8 +392,7 @@ rec {
     let
       defaultPrio = 100;
       getPrio = def: if def.value._type or "" == "override" then def.value.priority else defaultPrio;
-      min = x: y: if x < y then x else y;
-      highestPrio = fold (def: prio: min (getPrio def) prio) 9999 defs;
+      highestPrio = foldl' (prio: def: min (getPrio def) prio) 9999 defs;
       strip = def: if def.value._type or "" == "override" then def // { value = def.value.content; } else def;
     in concatMap (def: if getPrio def == highestPrio then [(strip def)] else []) defs;
 

lib/options.nix

@@ -4,7 +4,6 @@ let lib = import ./default.nix; in
 
 with import ./trivial.nix;
 with import ./lists.nix;
-with import ./misc.nix;
 with import ./attrsets.nix;
 with import ./strings.nix;
 
@@ -20,6 +19,7 @@ rec {
     , apply ? null # Function that converts the option value to something else.
     , internal ? null # Whether the option is for NixOS developers only.
     , visible ? null # Whether the option shows up in the manual.
+    , readOnly ? null # Whether the option can be set only once
     , options ? null # Obsolete, used by types.optionSet.
     } @ attrs:
     attrs // { _type = "option"; };
@@ -53,32 +53,27 @@ rec {
     if length list == 1 then head list
     else if all isFunction list then x: mergeDefaultOption loc (map (f: f x) list)
     else if all isList list then concatLists list
-    else if all isAttrs list then fold lib.mergeAttrs {} list
-    else if all isBool list then fold lib.or false list
+    else if all isAttrs list then foldl' lib.mergeAttrs {} list
+    else if all isBool list then foldl' lib.or false list
     else if all isString list then lib.concatStrings list
     else if all isInt list && all (x: x == head list) list then head list
     else throw "Cannot merge definitions of `${showOption loc}' given in ${showFiles (getFiles defs)}.";
 
-  /* Obsolete, will remove soon.  Specify an option type or apply
-     function instead.  */
-  mergeTypedOption = typeName: predicate: merge: loc: list:
-    let list' = map (x: x.value) list; in
-    if all predicate list then merge list'
-    else throw "Expected a ${typeName}.";
-
-  mergeEnableOption = mergeTypedOption "boolean"
-    (x: true == x || false == x) (fold lib.or false);
-
-  mergeListOption = mergeTypedOption "list" isList concatLists;
-
-  mergeStringOption = mergeTypedOption "string" isString lib.concatStrings;
-
   mergeOneOption = loc: defs:
     if defs == [] then abort "This case should never happen."
     else if length defs != 1 then
       throw "The unique option `${showOption loc}' is defined multiple times, in ${showFiles (getFiles defs)}."
     else (head defs).value;
 
+  /* "Merge" option definitions by checking that they all have the same value. */
+  mergeEqualOption = loc: defs:
+    if defs == [] then abort "This case should never happen."
+    else foldl' (val: def:
+      if def.value != val then
+        throw "The option `${showOption loc}' has conflicting definitions, in ${showFiles (getFiles defs)}."
+      else
+        val) (head defs).value defs;
+
   getValues = map (x: x.value);
   getFiles = map (x: x.file);
 
@@ -88,7 +83,7 @@ rec {
   optionAttrSetToDocList = optionAttrSetToDocList' [];
 
   optionAttrSetToDocList' = prefix: options:
-    fold (opt: rest:
+    concatMap (opt:
       let
         docOption = rec {
           name = showOption opt.loc;
@@ -96,6 +91,7 @@ rec {
           declarations = filter (x: x != unknownModule) opt.declarations;
           internal = opt.internal or false;
           visible = opt.visible or true;
+          readOnly = opt.readOnly or false;
           type = opt.type.name or null;
         }
         // (if opt ? example then { example = scrubOptionValue opt.example; } else {})
@@ -106,8 +102,7 @@ rec {
           let ss = opt.type.getSubOptions opt.loc;
           in if ss != {} then optionAttrSetToDocList' opt.loc ss else [];
       in
-        # FIXME: expensive, O(n^2)
-        [ docOption ] ++ subOptions ++ rest) [] (collect isOption options);
+        [ docOption ] ++ subOptions) (collect isOption options);
 
 
   /* This function recursively removes all derivation attributes from

lib/strings.nix

@@ -8,11 +8,15 @@ in
 
 rec {
 
-  inherit (builtins) stringLength substring head tail isString;
+  inherit (builtins) stringLength substring head tail isString replaceStrings;
 
 
   # Concatenate a list of strings.
-  concatStrings = lib.fold (x: y: x + y) "";
+  concatStrings =
+    if builtins ? concatStringsSep then
+      builtins.concatStringsSep ""
+    else
+      lib.foldl' (x: y: x + y) "";
 
 
   # Map a function over a list and concatenate the resulting strings.
@@ -25,14 +29,13 @@ rec {
   intersperse = separator: list:
     if list == [] || length list == 1
     then list
-    else [(head list) separator]
-         ++ (intersperse separator (tail list));
+    else tail (lib.concatMap (x: [separator x]) list);
 
 
   # Concatenate a list of strings with a separator between each element, e.g.
   # concatStringsSep " " ["foo" "bar" "xyzzy"] == "foo bar xyzzy"
-  concatStringsSep = separator: list:
-    concatStrings (intersperse separator list);
+  concatStringsSep = builtins.concatStringsSep or (separator: list:
+    concatStrings (intersperse separator list));
 
   concatMapStringsSep = sep: f: list: concatStringsSep sep (map f list);
   concatImapStringsSep = sep: f: list: concatStringsSep sep (lib.imap f list);
@@ -63,13 +66,13 @@ rec {
 
   # Determine whether a string has given prefix/suffix.
   hasPrefix = pref: str:
-    eqStrings (substring 0 (stringLength pref) str) pref;
+    substring 0 (stringLength pref) str == pref;
   hasSuffix = suff: str:
     let
       lenStr = stringLength str;
       lenSuff = stringLength suff;
     in lenStr >= lenSuff &&
-       eqStrings (substring (lenStr - lenSuff) lenStr str) suff;
+       substring (lenStr - lenSuff) lenStr str == suff;
 
 
   # Convert a string to a list of characters (i.e. singleton strings).
@@ -78,63 +81,57 @@ rec {
   # will likely be horribly inefficient; Nix is not a general purpose
   # programming language.  Complex string manipulations should, if
   # appropriate, be done in a derivation.
-  stringToCharacters = s: let l = stringLength s; in
-    if l == 0
-    then []
-    else map (p: substring p 1 s) (lib.range 0 (l - 1));
+  stringToCharacters = s:
+    map (p: substring p 1 s) (lib.range 0 (stringLength s - 1));
 
 
-  # Manipulate a string charcater by character and replace them by strings
-  # before concatenating the results.
+  # Manipulate a string charactter by character and replace them by
+  # strings before concatenating the results.
   stringAsChars = f: s:
     concatStrings (
       map f (stringToCharacters s)
     );
 
 
-  # same as vim escape function.
-  # Each character contained in list is prefixed by "\"
-  escape = list : string :
-    stringAsChars (c: if lib.elem c list then "\\${c}" else c) string;
+  # Escape occurrence of the elements of ‘list’ in ‘string’ by
+  # prefixing it with a backslash. For example, ‘escape ["(" ")"]
+  # "(foo)"’ returns the string ‘\(foo\)’.
+  escape = list: replaceChars list (map (c: "\\${c}") list);
 
 
-  # still ugly slow. But more correct now
-  # [] for zsh
+  # Escape all characters that have special meaning in the Bourne shell.
   escapeShellArg = lib.escape (stringToCharacters "\\ ';$`()|<>\t*[]");
 
 
-  # replace characters by their substitutes.  This function is equivalent to
-  # the `tr' command except that one character can be replace by multiple
-  # ones.  e.g.,
-  # replaceChars ["<" ">"] ["&lt;" "&gt;"] "<foo>" returns "&lt;foo&gt;".
-  replaceChars = del: new: s:
+  # Obsolete - use replaceStrings instead.
+  replaceChars = builtins.replaceStrings or (
+    del: new: s:
     let
+      substList = lib.zipLists del new;
       subst = c:
-        (lib.fold
-          (sub: res: if sub.fst == c then sub else res)
-          {fst = c; snd = c;} (lib.zipLists del new)
-        ).snd;
+        let found = lib.findFirst (sub: sub.fst == c) null substList; in
+        if found == null then
+          c
+        else
+          found.snd;
     in
-      stringAsChars subst s;
+      stringAsChars subst s);
 
 
-  # Case conversion utilities
+  # Case conversion utilities.
   lowerChars = stringToCharacters "abcdefghijklmnopqrstuvwxyz";
   upperChars = stringToCharacters "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
   toLower = replaceChars upperChars lowerChars;
   toUpper = replaceChars lowerChars upperChars;
 
-  # Appends string context from another string
+
+  # Appends string context from another string.
   addContextFrom = a: b: substring 0 0 a + b;
 
-  # Compares strings not requiring context equality
-  # Obviously, a workaround but works on all Nix versions
-  eqStrings = a: b: addContextFrom b a == addContextFrom a b;
 
-
-  # Cut a string with a separator and produces a list of strings which were
-  # separated by this separator. e.g.,
-  # `splitString "." "foo.bar.baz"' returns ["foo" "bar" "baz"].
+  # Cut a string with a separator and produces a list of strings which
+  # were separated by this separator; e.g., `splitString "."
+  # "foo.bar.baz"' returns ["foo" "bar" "baz"].
   splitString = _sep: _s:
     let
       sep = addContextFrom _s _sep;
@@ -177,7 +174,7 @@ rec {
       sufLen = stringLength suf;
       sLen = stringLength s;
     in
-      if sufLen <= sLen && eqStrings suf (substring (sLen - sufLen) sufLen s) then
+      if sufLen <= sLen && suf == substring (sLen - sufLen) sufLen s then
         substring 0 (sLen - sufLen) s
       else
         s;
@@ -196,21 +193,22 @@ rec {
 
 
   # Extract name with version from URL. Ask for separator which is
-  # supposed to start extension
-  nameFromURL = url: sep: let
-    components = splitString "/" url;
-    filename = lib.last components;
-    name = builtins.head (splitString sep filename);
-  in
-  assert ! eqStrings name filename;
-  name;
+  # supposed to start extension.
+  nameFromURL = url: sep:
+    let
+      components = splitString "/" url;
+      filename = lib.last components;
+      name = builtins.head (splitString sep filename);
+    in assert name !=  filename; name;
 
 
   # Create an --{enable,disable}-<feat> string that can be passed to
   # standard GNU Autoconf scripts.
   enableFeature = enable: feat: "--${if enable then "enable" else "disable"}-${feat}";
 
-  # Create a fixed width string with additional prefix to match required width
+
+  # Create a fixed width string with additional prefix to match
+  # required width.
   fixedWidthString = width: filler: str:
     let
       strw = lib.stringLength str;
@@ -219,6 +217,12 @@ rec {
       assert strw <= width;
       if strw == width then str else filler + fixedWidthString reqWidth filler str;
 
-  # Format a number adding leading zeroes up to fixed width
+
+  # Format a number adding leading zeroes up to fixed width.
   fixedWidthNumber = width: n: fixedWidthString width "0" (toString n);
+
+
+  # Check whether a value is a store path.
+  isStorePath = x: builtins.substring 0 1 (toString x) == "/" && dirOf (builtins.toPath x) == builtins.storeDir;
+
 }

lib/tests/modules.sh

@@ -12,7 +12,7 @@ evalConfig() {
     local attr=$1
     shift;
     local script="import ./default.nix { modules = [ $@ ];}"
-    nix-instantiate --timeout 1 -E "$script" -A "$attr" --eval-only
+    nix-instantiate --timeout 1 -E "$script" -A "$attr" --eval-only --show-trace
 }
 
 reportFailure() {
@@ -100,7 +100,15 @@ checkConfigOutput 'true' "$@" ./define-enable.nix ./define-loaOfSub-foo-if-enabl
 checkConfigOutput 'true' "$@" ./define-enable.nix ./define-loaOfSub-foo-enable-if.nix
 
 # Check _module.args.
-checkConfigOutput "true" config.enable ./declare-enable.nix ./custom-arg-define-enable.nix
+set -- config.enable ./declare-enable.nix ./define-enable-with-custom-arg.nix
+checkConfigError 'while evaluating the module argument .*custom.* in .*define-enable-with-custom-arg.nix.*:' "$@"
+checkConfigOutput "true" "$@" ./define-_module-args-custom.nix
+
+# Check that using _module.args on imports cause infinite recursions, with
+# the proper error context.
+set -- "$@" ./define-_module-args-custom.nix ./import-custom-arg.nix
+checkConfigError 'while evaluating the module argument .*custom.* in .*import-custom-arg.nix.*:' "$@"
+checkConfigError 'infinite recursion encountered' "$@"
 
 # Check _module.check.
 set -- config.enable ./declare-enable.nix ./define-enable.nix ./define-loaOfSub-foo.nix

lib/tests/modules/define-_module-args-custom.nix

@@ -0,0 +1,7 @@
+{ lib, ... }:
+
+{
+  config = {
+    _module.args.custom = true;
+  };
+}

lib/tests/modules/define-enable-with-custom-arg.nix

@@ -2,7 +2,6 @@
 
 {
   config = {
-    _module.args.custom = true;
     enable = custom;
   };
 }

lib/tests/modules/import-custom-arg.nix

@@ -0,0 +1,6 @@
+{ lib, custom, ... }:
+
+{
+  imports = []
+  ++ lib.optional custom ./define-enable-force.nix;
+}

lib/trivial.nix

@@ -22,7 +22,7 @@ rec {
   inherit (builtins)
     pathExists readFile isBool isFunction
     isInt add sub lessThan
-    seq deepSeq;
+    seq deepSeq genericClosure;
 
   # Return the Nixpkgs version number.
   nixpkgsVersion =

lib/types.nix

@@ -6,7 +6,7 @@ with import ./attrsets.nix;
 with import ./options.nix;
 with import ./trivial.nix;
 with import ./strings.nix;
-with {inherit (import ./modules.nix) mergeDefinitions; };
+with {inherit (import ./modules.nix) mergeDefinitions filterOverrides; };
 
 rec {
 
@@ -54,7 +54,7 @@ rec {
     bool = mkOptionType {
       name = "boolean";
       check = isBool;
-      merge = loc: fold (x: y: x.value || y) false;
+      merge = mergeEqualOption;
     };
 
     int = mkOptionType {
@@ -88,20 +88,22 @@ rec {
     attrs = mkOptionType {
       name = "attribute set";
       check = isAttrs;
-      merge = loc: fold (def: mergeAttrs def.value) {};
+      merge = loc: foldl' (res: def: mergeAttrs res def.value) {};
     };
 
     # derivation is a reserved keyword.
     package = mkOptionType {
       name = "derivation";
-      check = isDerivation;
-      merge = mergeOneOption;
+      check = x: isDerivation x || isStorePath x;
+      merge = loc: defs:
+        let res = mergeOneOption loc defs;
+        in if isDerivation res then res else toDerivation res;
     };
 
     path = mkOptionType {
       name = "path";
       # Hacky: there is no ‘isPath’ primop.
-      check = x: builtins.unsafeDiscardStringContext (builtins.substring 0 1 (toString x)) == "/";
+      check = x: builtins.substring 0 1 (toString x) == "/";
       merge = mergeOneOption;
     };
 
@@ -164,6 +166,23 @@ rec {
         substSubModules = m: loaOf (elemType.substSubModules m);
       };
 
+    # List or element of ...
+    loeOf = elemType: mkOptionType {
+      name = "element or list of ${elemType.name}s";
+      check = x: isList x || elemType.check x;
+      merge = loc: defs:
+        let
+          defs' = filterOverrides defs;
+          res = (head defs').value;
+        in
+        if isList res then concatLists (getValues defs')
+        else if lessThan 1 (length defs') then
+          throw "The option `${showOption loc}' is defined multiple times, in ${showFiles (getFiles defs)}."
+        else if !isString res then
+          throw "The option `${showOption loc}' does not have a string value, in ${showFiles (getFiles defs)}."
+        else res;
+    };
+
     uniq = elemType: mkOptionType {
       inherit (elemType) name check;
       merge = mergeOneOption;