add custom std/trivial.nix

nib/std/default.nix

@@ -1,9 +1,11 @@
 {...} @ args: let
   attrs = import ./attrs.nix args;
   lists = import ./lists.nix args;
+  trivial = import ./trivial.nix args;
 in
   attrs.mergeAttrsList [
     # submodule is included directly to this module (ie self.myFunc)
     attrs
     lists
+    trivial
   ]

nib/std/trivial.nix

@@ -0,0 +1,13 @@
+{...}: {
+  id = x: x;
+
+  min = x: y:
+    if x < y
+    then x
+    else y;
+
+  max = x: y:
+    if x > y
+    then x
+    else y;
+}