Convert libs to a fixed-point

This does break the API of being able to import any lib file and get
its libs, however I'm not sure people did this.

I made this while exploring being able to swap out docFn with a stub
in #2305, to avoid functor performance problems. I don't know if that
is going to move forward (or if it is a problem or not,) but after
doing all this work figured I'd put it up anyway :)

Two notable advantages to this approach:

1. when a lib inherits another lib's functions, it doesn't
   automatically get put in to the scope of lib
2. when a lib implements a new obscure functions, it doesn't
   automatically get put in to the scope of lib

Using the test script (later in this commit) I got the following diff
on the API:

  + diff master fixed-lib
  11764a11765,11766
  > .types.defaultFunctor
  > .types.defaultTypeMerge
  11774a11777,11778
  > .types.isOptionType
  > .types.isType
  11781a11786
  > .types.mkOptionType
  11788a11794
  > .types.setType
  11795a11802
  > .types.types

This means that this commit _adds_ to the API, however I can't find a
way to fix these last remaining discrepancies. At least none are
_removed_.

Test script (run with nix-repl in the PATH):

  #!/bin/sh

  set -eux

  repl() {
      suff=${1:-}
      echo "(import ./lib)$suff" \
          | nix-repl 2>&1
  }

  attrs_to_check() {
      repl "${1:-}" \
          | tr ';'  $'\n' \
          | grep "\.\.\." \
          | cut -d' ' -f2 \
          | sed -e "s/^/${1:-}./" \
          | sort
  }

  summ() {
      repl "${1:-}" \
          | tr ' ' $'\n' \
          | sort \
          | uniq
  }

  deep_summ() {
      suff="${1:-}"
      depth="${2:-4}"
      depth=$((depth - 1))
      summ "$suff"

      for attr in $(attrs_to_check "$suff" | grep -v "types.types"); do
          if [ $depth -eq 0 ]; then
              summ "$attr" | sed -e "s/^/$attr./"
          else
              deep_summ "$attr" "$depth" | sed -e "s/^/$attr./"
          fi
      done
  }

  (
      cd nixpkgs

      #git add .
      #git commit -m "Auto-commit, sorry" || true
      git checkout fixed-lib
      deep_summ > ../fixed-lib
      git checkout master
      deep_summ > ../master
  )

  if diff master fixed-lib; then
      echo "SHALLOW MATCH!"
  fi

  (
      cd nixpkgs
      git checkout fixed-lib
      repl .types
  )

1 files changed, 121 insertions, 52 deletions

diff --git a/lib/default.nix b/lib/default.nix
index 3893e349db3..3e30ec515fc 100644
--- a/lib/default.nix
+++ b/lib/default.nix
@@ -5,58 +5,127 @@
  */
 let
 
-  # often used, or depending on very little
-  trivial = import ./trivial.nix;
-  fixedPoints = import ./fixed-points.nix;
-
-  # datatypes
-  attrsets = import ./attrsets.nix;
-  lists = import ./lists.nix;
-  strings = import ./strings.nix;
-  stringsWithDeps = import ./strings-with-deps.nix;
-
-  # packaging
-  customisation = import ./customisation.nix;
-  maintainers = import ./maintainers.nix;
-  meta = import ./meta.nix;
-  sources = import ./sources.nix;
-
-  # module system
-  modules = import ./modules.nix;
-  options = import ./options.nix;
-  types = import ./types.nix;
-
-  # constants
-  licenses = import ./licenses.nix;
-  systems = import ./systems;
-
-  # misc
-  debug = import ./debug.nix;
-  generators = import ./generators.nix;
-  misc = import ./deprecated.nix;
-
-  # domain-specific
-  sandbox = import ./sandbox.nix;
-  fetchers = import ./fetchers.nix;
-
-  # Eval-time filesystem handling
-  filesystem = import ./filesystem.nix;
-
-in
-  { inherit trivial fixedPoints
-            attrsets lists strings stringsWithDeps
-            customisation maintainers meta sources
-            modules options types
-            licenses systems
-            debug generators misc
-            sandbox fetchers filesystem;
+  callLibs = file: import file { inherit lib; };
+
+  lib = rec {
+
+    # often used, or depending on very little
+    trivial = callLibs ./trivial.nix;
+    fixedPoints = callLibs ./fixed-points.nix;
+
+    # datatypes
+    attrsets = callLibs ./attrsets.nix;
+    lists = callLibs ./lists.nix;
+    strings = callLibs ./strings.nix;
+    stringsWithDeps = callLibs ./strings-with-deps.nix;
+
+    # packaging
+    customisation = callLibs ./customisation.nix;
+    maintainers = callLibs ./maintainers.nix;
+    meta = callLibs ./meta.nix;
+    sources = callLibs ./sources.nix;
+
+
+    # module system
+    modules = callLibs ./modules.nix;
+    options = callLibs ./options.nix;
+    types = callLibs ./types.nix;
+
+    # constants
+    licenses = callLibs ./licenses.nix;
+    systems = callLibs ./systems;
+
+    # misc
+    debug = callLibs ./debug.nix;
+
+    generators = callLibs ./generators.nix;
+    misc = callLibs ./deprecated.nix;
+    # domain-specific
+    sandbox = callLibs ./sandbox.nix;
+    fetchers = callLibs ./fetchers.nix;
+
+    # Eval-time filesystem handling
+    filesystem = callLibs ./filesystem.nix;
 
     # back-compat aliases
     platforms = systems.doubles;
-  }
-  # !!! don't include everything at top-level; perhaps only the most
-  # commonly used functions.
-  // trivial // fixedPoints
-  // lists // strings // stringsWithDeps // attrsets // sources
-  // options // types // meta // debug // misc // modules
-  // customisation
+
+    inherit (builtins) add addErrorContext attrNames
+      concatLists deepSeq elem elemAt filter genericClosure genList
+      getAttr hasAttr head isAttrs isBool isFunction isInt isList
+      isString length lessThan listToAttrs pathExists readFile
+      replaceStrings seq stringLength sub substring tail;
+    inherit (trivial) id const concat or and boolToString mergeAttrs
+      flip mapNullable inNixShell min max importJSON warn info
+      nixpkgsVersion mod;
+
+    inherit (fixedPoints) fix fix' extends composeExtensions
+      makeExtensible makeExtensibleWithCustomName;
+    inherit (attrsets) attrByPath hasAttrByPath setAttrByPath
+      getAttrFromPath attrVals attrValues catAttrs filterAttrs
+      filterAttrsRecursive foldAttrs collect nameValuePair mapAttrs
+      mapAttrs' mapAttrsToList mapAttrsRecursive mapAttrsRecursiveCond
+      genAttrs isDerivation toDerivation optionalAttrs
+      zipAttrsWithNames zipAttrsWith zipAttrs recursiveUpdateUntil
+      recursiveUpdate matchAttrs overrideExisting getOutput getBin
+      getLib getDev chooseDevOutputs zipWithNames zip;
+    inherit (lists) singleton foldr fold foldl foldl' imap0 imap1
+      concatMap flatten remove findSingle findFirst any all count
+      optional optionals toList range partition zipListsWith zipLists
+      reverseList listDfs toposort sort take drop sublist last init
+      crossLists unique intersectLists subtractLists
+      mutuallyExclusive;
+    inherit (strings) concatStrings concatMapStrings concatImapStrings
+      intersperse concatStringsSep concatMapStringsSep
+      concatImapStringsSep makeSearchPath makeSearchPathOutput
+      makeLibraryPath makeBinPath makePerlPath optionalString
+      hasPrefix hasSuffix stringToCharacters stringAsChars escape
+      escapeShellArg escapeShellArgs replaceChars lowerChars upperChars
+      toLower toUpper addContextFrom splitString removePrefix
+      removeSuffix versionOlder versionAtLeast getVersion nameFromURL
+      enableFeature fixedWidthString fixedWidthNumber isStorePath
+      toInt readPathsFromFile fileContents;
+    inherit (stringsWithDeps) textClosureList textClosureMap
+      noDepEntry fullDepEntry packEntry stringAfter;
+    inherit (customisation) overrideDerivation makeOverridable
+      callPackageWith callPackagesWith addPassthru hydraJob makeScope;
+    inherit (meta) addMetaAttrs dontDistribute setName updateName
+      appendToName mapDerivationAttrset lowPrio lowPrioSet hiPrio
+      hiPrioSet;
+    inherit (sources) pathType pathIsDirectory cleanSourceFilter
+      cleanSource sourceByRegex sourceFilesBySuffices
+      commitIdFromGitRepo;
+    inherit (modules) evalModules closeModules unifyModuleSyntax
+      applyIfFunction unpackSubmodule packSubmodule mergeModules
+      mergeModules' mergeOptionDecls evalOptionValue mergeDefinitions
+      pushDownProperties dischargeProperties filterOverrides
+      sortProperties fixupOptionType mkIf mkAssert mkMerge mkOverride
+      mkOptionDefault mkDefault mkForce mkVMOverride mkStrict
+      mkFixStrictness mkOrder mkBefore mkAfter mkAliasDefinitions
+      mkAliasAndWrapDefinitions fixMergeModules mkRemovedOptionModule
+      mkRenamedOptionModule mkMergedOptionModule mkChangedOptionModule
+      mkAliasOptionModule doRename filterModules;
+    inherit (options) isOption mkEnableOption mkSinkUndeclaredOptions
+      mergeDefaultOption mergeOneOption mergeEqualOption getValues
+      getFiles optionAttrSetToDocList optionAttrSetToDocList'
+      scrubOptionValue literalExample showOption showFiles
+      unknownModule mkOption;
+    inherit (types) isType setType defaultTypeMerge defaultFunctor
+      isOptionType mkOptionType;
+    inherit (debug) addErrorContextToAttrs traceIf traceVal
+      traceXMLVal traceXMLValMarked traceSeq traceSeqN traceValSeq
+      traceValSeqN traceShowVal traceShowValMarked
+      showVal traceCall traceCall2 traceCall3 traceValIfNot runTests
+      testAllTrue strict traceCallXml attrNamesToStr;
+    inherit (misc) maybeEnv defaultMergeArg defaultMerge foldArgs
+      defaultOverridableDelayableArgs composedArgsAndFun
+      maybeAttrNullable maybeAttr ifEnable checkFlag getValue
+      checkReqs uniqList uniqListExt condConcat lazyGenericClosure
+      innerModifySumArgs modifySumArgs innerClosePropagation
+      closePropagation mapAttrsFlatten nvs setAttr setAttrMerge
+      mergeAttrsWithFunc mergeAttrsConcatenateValues
+      mergeAttrsNoOverride mergeAttrByFunc mergeAttrsByFuncDefaults
+      mergeAttrsByFuncDefaultsClean mergeAttrBy
+      prepareDerivationArgs nixType imap overridableDelayableArgs;
+  };
+in lib