lib: Use arithmetic operators rather than builtins.add etc.

lib/lists.nix

@@ -2,13 +2,7 @@
 
 with import ./trivial.nix;
 
-let
-
-  inc = builtins.add 1;
-
-  dec = n: builtins.sub n 1;
-
-in rec {
+rec {
 
   inherit (builtins) head tail length isList elemAt concatLists filter elem;
 
@@ -29,7 +23,7 @@ in rec {
       fold' = n:
         if n == len
         then nul
-        else op (elemAt list n) (fold' (inc n));
+        else op (elemAt list n) (fold' (n + 1));
     in fold' 0;
 
   # Left fold: `fold op nul [x_1 x_2 ... x_n] == op (... (op (op nul
@@ -38,12 +32,10 @@ in rec {
     let
       len = length list;
       foldl' = n:
-        if n == minus1
+        if n == -1
         then nul
-        else op (foldl' (dec n)) (elemAt list n);
-    in foldl' (dec (length list));
-
-  minus1 = dec 0;
+        else op (foldl' (n - 1)) (elemAt list n);
+    in foldl' (length list - 1);
 
 
   # map with index: `imap (i: v: "${v}-${toString i}") ["a" "b"] ==
@@ -54,7 +46,7 @@ in rec {
       imap' = n:
         if n == len
           then []
-          else [ (f (inc n) (elemAt list n)) ] ++ imap' (inc n);
+          else [ (f (n + 1) (elemAt list n)) ] ++ imap' (n + 1);
     in imap' 0;
 
 
@@ -104,7 +96,7 @@ in rec {
 
   # Count how many times function `pred' returns true for the elements
   # of `list'.
-  count = pred: fold (x: c: if pred x then inc c else c) 0;
+  count = pred: fold (x: c: if pred x then c + 1 else c) 0;
 
 
   # Return a singleton list or an empty list, depending on a boolean
@@ -125,9 +117,9 @@ in rec {
 
   # Return a list of integers from `first' up to and including `last'.
   range = first: last:
-    if lessThan last first
+    if last < first
     then []
-    else [first] ++ range (add first 1) last;
+    else [first] ++ range (first + 1) last;
 
 
   # Partition the elements of a list in two lists, `right' and
@@ -144,11 +136,11 @@ in rec {
     let
       len1 = length fst;
       len2 = length snd;
-      len = if lessThan len1 len2 then len1 else len2;
+      len = if len1 < len2 then len1 else len2;
       zipListsWith' = n:
         if n != len then
           [ (f (elemAt fst n) (elemAt snd n)) ]
-          ++ zipListsWith' (inc n)
+          ++ zipListsWith' (n + 1)
         else [];
     in zipListsWith' 0;
 
@@ -167,7 +159,7 @@ in rec {
     let
       len = length list;
       first = head list;
-      pivot' = n: acc@{ left, right }: let el = elemAt list n; next = pivot' (inc n); in
+      pivot' = n: acc@{ left, right }: let el = elemAt list n; next = pivot' (n + 1); in
         if n == len
           then acc
         else if strictLess first el
@@ -176,7 +168,7 @@ in rec {
           next { left = [ el ] ++ left; inherit right; };
       pivot = pivot' 1 { left = []; right = []; };
     in
-      if lessThan len 2 then list
+      if len < 2 then list
       else (sort strictLess pivot.left) ++  [ first ] ++  (sort strictLess pivot.right);
 
 
@@ -188,7 +180,7 @@ in rec {
         if n == len || n == count
           then []
         else
-          [ (elemAt list n) ] ++ take' (inc n);
+          [ (elemAt list n) ] ++ take' (n + 1);
     in take' 0;
 
 
@@ -197,16 +189,16 @@ in rec {
     let
       len = length list;
       drop' = n:
-        if n == minus1 || lessThan n count
+        if n == -1 || n < count
           then []
         else
-          drop' (dec n) ++ [ (elemAt list n) ];
-    in drop' (dec len);
+          drop' (n - 1) ++ [ (elemAt list n) ];
+    in drop' (len - 1);
 
 
   # Return the last element of a list.
   last = list:
-    assert list != []; elemAt list (dec (length list));
+    assert list != []; elemAt list (length list - 1);
 
 
   # Return all elements but the last
@@ -218,11 +210,11 @@ in rec {
     let
       len1 = length xs;
       len2 = length ys;
-      len = if lessThan len1 len2 then len1 else len2;
+      len = if len1 < len2 then len1 else len2;
       zipTwoLists' = n:
         if n != len then
           [ { first = elemAt xs n; second = elemAt ys n; } ]
-          ++ zipTwoLists' (inc n)
+          ++ zipTwoLists' (n + 1)
         else [];
     in zipTwoLists' 0;
 

lib/modules.nix

@@ -278,7 +278,7 @@ rec {
     let
       defaultPrio = 100;
       getPrio = def: if def.value._type or "" == "override" then def.value.priority else defaultPrio;
-      min = x: y: if builtins.lessThan x y then x else y;
+      min = x: y: if x < y then x else y;
       highestPrio = fold (def: prio: 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/strings.nix

@@ -2,7 +2,7 @@
 
 let lib = import ./default.nix;
 
-inherit (builtins) add sub lessThan length;
+inherit (builtins) length;
 
 in
 
@@ -79,7 +79,7 @@ rec {
   stringToCharacters = s: let l = stringLength s; in
     if l == 0
     then []
-    else map (p: substring p 1 s) (lib.range 0 (sub l 1));
+    else map (p: substring p 1 s) (lib.range 0 (l - 1));
 
 
   # Manipulate a string charcater by character and replace them by strings
@@ -123,7 +123,7 @@ rec {
   toUpper = replaceChars lowerChars upperChars;
 
   # Appends string context from another string
-  addContextFrom = a: b: (substring 0 0 a)+b;
+  addContextFrom = a: b: substring 0 0 a + b;
 
   # Compares strings not requiring context equality
   # Obviously, a workaround but works on all Nix versions
@@ -139,18 +139,18 @@ rec {
       s = addContextFrom _sep _s;
       sepLen = stringLength sep;
       sLen = stringLength s;
-      lastSearch = sub sLen sepLen;
+      lastSearch = sLen - sepLen;
       startWithSep = startAt:
         substring startAt sepLen s == sep;
 
       recurse = index: startAt:
-        let cutUntil = i: [(substring startAt (sub i startAt) s)]; in
-        if lessThan index lastSearch then
+        let cutUntil = i: [(substring startAt (i - startAt) s)]; in
+        if index < lastSearch then
           if startWithSep index then
-            let restartAt = add index sepLen; in
+            let restartAt = index + sepLen; in
             cutUntil index ++ recurse restartAt restartAt
           else
-            recurse (add index 1) startAt
+            recurse (index + 1) startAt
         else
           cutUntil sLen;
     in

lib/systems.nix

@@ -24,7 +24,7 @@ rec {
 
   isCpuType = x: isType "cpu-type" x
     && elem x.bits [8 16 32 64 128]
-    && (builtins.lessThan 8 x.bits -> isSignificantByte x.significantByte);
+    && (8 < x.bits -> isSignificantByte x.significantByte);
 
   cpuTypes = with significantBytes;
     setTypes "cpu-type" {