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Big cleanup of the NixOS module system

Browse source 
The major changes are:

* The evaluation is now driven by the declared options.  In
  particular, this fixes the long-standing problem with lack of
  laziness of disabled option definitions.  Thus, a configuration like

    config = mkIf false {
      environment.systemPackages = throw "bla";
    };

  will now evaluate without throwing an error.  This also improves
  performance since we're not evaluating unused option definitions.

* The implementation of properties is greatly simplified.

* There is a new type constructor "submodule" that replaces
  "optionSet".  Unlike "optionSet", "submodule" gets its option
  declarations as an argument, making it more like "listOf" and other
  type constructors.  A typical use is:

    foo = mkOption {
      type = type.attrsOf (type.submodule (
        { config, ... }:
        { bar = mkOption { ... };
          xyzzy = mkOption { ... };
        }));
    };

  Existing uses of "optionSet" are automatically mapped to
  "submodule".

* Modules are now checked for unsupported attributes: you get an error
  if a module contains an attribute other than "config", "options" or
  "imports".

* The new implementation is faster and uses much less memory.
This commit is contained in:
Eelco Dolstra 2013-10-28 00:56:22 +01:00
parent f4dadc5df8
commit 0e333688ce
9 changed files with 294 additions and 974 deletions
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5
lib/default.nix
View file

@ -8,7 +8,6 @@ let
sources = import ./sources.nix;
modules = import ./modules.nix;
options = import ./options.nix;
properties = import ./properties.nix;
types = import ./types.nix;
meta = import ./meta.nix;
debug = import ./debug.nix;
@ -21,13 +20,13 @@ let
in
{ inherit trivial lists strings stringsWithDeps attrsets sources options
properties modules types meta debug maintainers licenses platforms systems;
modules types meta debug maintainers licenses platforms systems;
# Pull in some builtins not included elsewhere.
inherit (builtins) pathExists readFile;
}
# !!! don't include everything at top-level; perhaps only the most
# commonly used functions.
// trivial // lists // strings // stringsWithDeps // attrsets // sources
// properties // options // types // meta // debug // misc // modules
// options // types // meta // debug // misc // modules
// systems
// customisation

5
lib/lists.nix
View file

@ -165,10 +165,11 @@ in rec {
zipLists = zipListsWith (fst: snd: { inherit fst snd; });
# Reverse the order of the elements of a list.
# Reverse the order of the elements of a list. FIXME: O(n^2)!
reverseList = 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

580
lib/modules.nix
View file

@ -1,379 +1,245 @@
# NixOS module handling.
let lib = import ./default.nix; in
with { inherit (builtins) head; };
with import ./trivial.nix;
with import ./lists.nix;
with import ./misc.nix;
with import ./attrsets.nix;
with import ./options.nix;
with import ./properties.nix;
with import ./.. {};
with lib;
rec {
# Unfortunately this can also be a string.
isPath = x: !(
builtins.isFunction x
|| builtins.isAttrs x
|| builtins.isInt x
|| builtins.isBool x
|| builtins.isList x
);
importIfPath = path:
if isPath path then
import path
else
path;
applyIfFunction = f: arg:
if builtins.isFunction f then
f arg
else
f;
isModule = m:
(m ? config && isAttrs m.config && ! isOption m.config)
|| (m ? options && isAttrs m.options && ! isOption m.options);
# Convert module to a set which has imports / options and config
# attributes.
unifyModuleSyntax = m:
/* Evaluate a set of modules. The result is a set of two
attributes: ‘options’: the nested set of all option declarations,
and ‘config’: the nested set of all option values. */
evalModules = modules: args:
let
delayedModule = delayProperties m;
getImports =
toList (rmProperties (delayedModule.require or []));
getImportedPaths = filter isPath getImports;
getImportedSets = filter (x: !isPath x) getImports;
getConfig =
removeAttrs delayedModule ["require" "key" "imports"];
args' = args // result;
closed = closeModules modules args';
# Note: the list of modules is reversed to maintain backward
# compatibility with the old module system. Not sure if this is
# the most sensible policy.
options = mergeModules (reverseList closed);
config = yieldConfig options;
yieldConfig = mapAttrs (n: v: if isOption v then v.value else yieldConfig v);
result = { inherit options config; };
in result;
/* Close a set of modules under the ‘imports’ relation. */
closeModules = modules: args:
let
coerceToModule = n: x:
if isAttrs x || builtins.isFunction x then
unifyModuleSyntax "anon-${toString n}" (applyIfFunction x args)
else
unifyModuleSyntax (toString x) (applyIfFunction (import x) args);
toClosureList = imap (path: coerceToModule path);
in
if isModule m then
{ key = "<unknown location>"; } // m
builtins.genericClosure {
startSet = toClosureList modules;
operator = m: toClosureList m.imports;
};
/* Massage a module into canonical form, that is, a set consisting
of ‘options’, ‘config’ and ‘imports’ attributes. */
unifyModuleSyntax = key: m:
if m ? config || m ? options || m ? imports then
let badAttrs = removeAttrs m ["imports" "options" "config"]; in
if badAttrs != {} then
throw "Module `${key}' has an unsupported attribute `${head (attrNames badAttrs)}'. ${builtins.toXML m} "
else
{ key = "<unknown location>";
imports = (m.imports or []) ++ getImportedPaths;
config = getConfig;
} // (
if getImportedSets != [] then
assert length getImportedSets == 1;
{ options = head getImportedSets; }
{ inherit key;
imports = m.imports or [];
options = m.options or {};
config = m.config or {};
}
else
{ inherit key;
imports = m.require or [];
options = {};
config = m;
};
applyIfFunction = f: arg: if builtins.isFunction f then f arg else f;
/* Merge a list of modules. This will recurse over the option
declarations in all modules, combining them into a single set.
At the same time, for each option declaration, it will merge the
corresponding option definitions in all machines, returning them
in the ‘value’ attribute of each option. */
mergeModules = modules:
mergeModules' [] (map (m: m.options) modules) (concatMap (m: pushDownProperties m.config) modules);
mergeModules' = loc: options: configs:
zipAttrsWith (name: vals:
let loc' = loc ++ [name]; in
if all isOption vals then
let opt = fixupOptionType loc' (mergeOptionDecls loc' vals);
in evalOptionValue loc' opt (catAttrs name configs)
else if any isOption vals then
throw "There are options with the prefix `${showOption loc'}', which is itself an option."
else
mergeModules' loc' vals (concatMap pushDownProperties (catAttrs name configs))
) options;
/* Merge multiple option declarations into a single declaration. In
general, there should be only one declaration of each option.
The exception is the ‘options’ attribute, which specifies
sub-options. These can be specified multiple times to allow one
module to add sub-options to an option declared somewhere else
(e.g. multiple modules define sub-options for ‘fileSystems’). */
mergeOptionDecls = loc: opts:
fold (opt1: opt2:
if opt1 ? default && opt2 ? default ||
opt1 ? example && opt2 ? example ||
opt1 ? description && opt2 ? description ||
opt1 ? merge && opt2 ? merge ||
opt1 ? apply && opt2 ? apply ||
opt1 ? type && opt2 ? type
then
throw "Conflicting declarations of the option `${showOption loc}'."
else
opt1 // opt2
// optionalAttrs (opt1 ? options && opt2 ? options)
{ options = [ opt1.options opt2.options ]; }
) {} opts;
/* Merge all the definitions of an option to produce the final
config value. */
evalOptionValue = loc: opt: defs:
let
# Process mkMerge and mkIf properties.
defs' = concatMap dischargeProperties defs;
# Process mkOverride properties, adding in the default
# value specified in the option declaration (if any).
defsFinal = filterOverrides (optional (opt ? default) (mkOptionDefault opt.default) ++ defs');
# Type-check the remaining definitions, and merge them
# if possible.
merged =
if defsFinal == [] then
throw "The option `${showOption loc}' is used but not defined."
else
if all opt.type.check defsFinal then
opt.type.merge defsFinal
#throw "The option `${showOption loc}' has multiple values (with no way to merge them)."
else
{}
);
unifyOptionModule = {key ? "<unknown location>"}: name: index: m: (args:
let
module = lib.applyIfFunction m args;
key_ = rec {
file = key;
option = name;
number = index;
outPath = key;
};
in if lib.isModule module then
{ key = key_; } // module
else
{ key = key_; options = module; }
);
moduleClosure = initModules: args:
let
moduleImport = origin: index: m:
let m' = applyIfFunction (importIfPath m) args;
in (unifyModuleSyntax m') // {
# used by generic closure to avoid duplicated imports.
key =
if isPath m then m
else m'.key or (newModuleName origin index);
};
getImports = m: m.imports or [];
newModuleName = origin: index:
"${origin.key}:<import-${toString index}>";
topLevel = {
key = "<top-level>";
throw "A value of the option `${showOption loc}' has a bad type.";
# 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 //
{ inherit value;
definitions = defsFinal;
isDefined = defsFinal != [];
};
in
(lazyGenericClosure {
startSet = imap (moduleImport topLevel) initModules;
operator = m: imap (moduleImport m) (getImports m);
});
/* Given a config set, expand mkMerge properties, and push down the
mkIf properties into the children. The result is a list of
config sets that do not have properties at top-level. For
example,
mkMerge [ { boot = set1; } (mkIf cond { boot = set2; services = set3; }) ]
moduleApply = funs: module:
lib.mapAttrs (name: value:
if builtins.hasAttr name funs then
let fun = lib.getAttr name funs; in
fun value
is transformed into
[ { boot = set1; } { boot = mkIf cond set2; services mkIf cond set3; } ].
This transform is the critical step that allows mkIf conditions
to refer to the full configuration without creating an infinite
recursion.
*/
pushDownProperties = cfg:
if cfg._type or "" == "merge" then
concatMap pushDownProperties cfg.contents
else if cfg._type or "" == "if" then
map (mapAttrs (n: v: mkIf cfg.condition v)) (pushDownProperties cfg.content)
else
# FIXME: handle mkOverride?
[ cfg ];
/* Given a config value, expand mkMerge properties, and discharge
any mkIf conditions. That is, this is the place where mkIf
conditions are actually evaluated. The result is a list of
config values. For example, ‘mkIf false x’ yields ‘[]’,
‘mkIf true x’ yields ‘[x]’, and
mkMerge [ 1 (mkIf true 2) (mkIf true (mkIf false 3)) ]
yields ‘[ 1 2 ]’.
*/
dischargeProperties = def:
if def._type or "" == "merge" then
concatMap dischargeProperties def.contents
else if def._type or "" == "if" then
if def.condition then
dischargeProperties def.content
else
value
) module;
# Handle mkMerge function left behind after a delay property.
moduleFlattenMerge = module:
if module ? config &&
isProperty module.config &&
isMerge module.config.property
then
(map (cfg: { key = module.key; config = cfg; }) module.config.content)
++ [ (module // { config = {}; }) ]
[ ]
else
[ module ];
[ def ];
/* Given a list of config value, process the mkOverride properties,
that is, return the values that have the highest (that
is,. numerically lowest) priority, and strip the mkOverride
properties. For example,
# Handle mkMerge attributes which are left behind by previous delay
# properties and convert them into a list of modules. Delay properties
# inside the config attribute of a module and create a second module if a
# mkMerge attribute was left behind.
#
# Module -> [ Module ]
delayModule = module:
map (moduleApply { config = delayProperties; }) (moduleFlattenMerge module);
[ (mkOverride 10 "a") (mkOverride 20 "b") "z" (mkOverride 10 "d") ]
evalDefinitions = opt: values:
if opt.type.delayOnGlobalEval or false then
map (delayPropertiesWithIter opt.type.iter opt.name)
(evalLocalProperties values)
else
evalProperties values;
selectModule = name: m:
{ inherit (m) key;
} // (
if m ? options && builtins.hasAttr name m.options then
{ options = lib.getAttr name m.options; }
else {}
) // (
if m ? config && builtins.hasAttr name m.config then
{ config = lib.getAttr name m.config; }
else {}
);
filterModules = name: modules:
filter (m: m ? config || m ? options) (
map (selectModule name) modules
);
modulesNames = modules:
lib.concatMap (m: []
++ optionals (m ? options) (lib.attrNames m.options)
++ optionals (m ? config) (lib.attrNames m.config)
) modules;
moduleZip = funs: modules:
lib.mapAttrs (name: fun:
fun (catAttrs name modules)
) funs;
moduleMerge = path: modules_:
yields ‘[ "a" "d" ]’. Note that "z" has the default priority 100.
*/
filterOverrides = defs:
let
addName = name:
if path == "" then name else path + "." + name;
defaultPrio = 100;
getPrio = def: if def._type or "" == "override" then def.priority else defaultPrio;
min = x: y: if x < y then x else y;
highestPrio = fold (def: prio: min (getPrio def) prio) 9999 defs;
strip = def: if def._type or "" == "override" then def.content else def;
in concatMap (def: if getPrio def == highestPrio then [(strip def)] else []) defs;
modules = concatLists (map delayModule modules_);
modulesOf = name: filterModules name modules;
declarationsOf = name: filter (m: m ? options) (modulesOf name);
definitionsOf = name: filter (m: m ? config ) (modulesOf name);
recurseInto = name:
moduleMerge (addName name) (modulesOf name);
recurseForOption = name: modules: args:
moduleMerge name (
moduleClosure modules args
);
errorSource = modules:
"The error may come from the following files:\n" + (
lib.concatStringsSep "\n" (
map (m:
if m ? key then toString m.key else "<unknown location>"
) modules
)
);
eol = "\n";
allNames = modulesNames modules;
getResults = m:
let fetchResult = s: mapAttrs (n: v: v.result) s; in {
options = fetchResult m.options;
config = fetchResult m.config;
};
endRecursion = { options = {}; config = {}; };
in if modules == [] then endRecursion else
getResults (fix (crossResults: moduleZip {
options = lib.zipWithNames allNames (name: values: rec {
config = lib.getAttr name crossResults.config;
declarations = declarationsOf name;
declarationSources =
map (m: {
source = m.key;
}) declarations;
hasOptions = values != [];
isOption = any lib.isOption values;
decls = # add location to sub-module options.
map (m:
mapSubOptions
(unifyOptionModule {inherit (m) key;} name)
m.options
) declarations;
decl =
lib.addErrorContext "${eol
}while enhancing option `${addName name}':${eol
}${errorSource declarations}${eol
}" (
addOptionMakeUp
{ name = addName name; recurseInto = recurseForOption; }
(mergeOptionDecls decls)
);
value = decl // (with config; {
inherit (config) isNotDefined;
isDefined = ! isNotDefined;
declarations = declarationSources;
definitions = definitionSources;
config = strictResult;
});
recurse = (recurseInto name).options;
result =
if isOption then value
else if !hasOptions then {}
else if all isAttrs values then recurse
else
throw "${eol
}Unexpected type where option declarations are expected.${eol
}${errorSource declarations}${eol
}";
});
config = lib.zipWithNames allNames (name: values_: rec {
option = lib.getAttr name crossResults.options;
definitions = definitionsOf name;
definitionSources =
map (m: {
source = m.key;
value = m.config;
}) definitions;
values = values_ ++
optionals (option.isOption && option.decl ? extraConfigs)
option.decl.extraConfigs;
defs = evalDefinitions option.decl values;
isNotDefined = defs == [];
value =
lib.addErrorContext "${eol
}while evaluating the option `${addName name}':${eol
}${errorSource (modulesOf name)}${eol
}" (
let opt = option.decl; in
opt.apply (
if isNotDefined then
opt.default or (throw "Option `${addName name}' not defined and does not have a default value.")
else opt.merge defs
)
);
strictResult = builtins.tryEval (builtins.toXML value);
recurse = (recurseInto name).config;
configIsAnOption = v: isOption (rmProperties v);
errConfigIsAnOption =
let badModules = filter (m: configIsAnOption m.config) definitions; in
"${eol
}Option ${addName name} is defined in the configuration section.${eol
}${errorSource badModules}${eol
}";
errDefinedWithoutDeclaration =
let badModules = definitions; in
"${eol
}Option '${addName name}' defined without option declaration.${eol
}${errorSource badModules}${eol
}";
result =
if option.isOption then value
else if !option.hasOptions then throw errDefinedWithoutDeclaration
else if any configIsAnOption values then throw errConfigIsAnOption
else if all isAttrs values then recurse
# plain value during the traversal
else throw errDefinedWithoutDeclaration;
});
} modules));
fixMergeModules = initModules: {...}@args:
lib.fix (result:
# This trick avoids an infinite loop because names of attribute
# are know and it is not required to evaluate the result of
# moduleMerge to know which attributes are present as arguments.
let module = { inherit (result) options config; }; in
moduleMerge "" (
moduleClosure initModules (module // args)
)
);
# Visit all definitions to raise errors related to undeclared options.
checkModule = path: {config, options, ...}@m:
/* Hack for backward compatibility: convert options of type
optionSet to configOf. FIXME: remove eventually. */
fixupOptionType = loc: opt:
let
eol = "\n";
addName = name:
if path == "" then name else path + "." + name;
in
if lib.isOption options then
if options ? options then
options.type.fold
(cfg: res: res && checkModule (options.type.docPath path) cfg._args)
true config
else
true
else if isAttrs options && lib.attrNames m.options != [] then
all (name:
lib.addErrorContext "${eol
}while checking the attribute `${addName name}':${eol
}" (checkModule (addName name) (selectModule name m))
) (lib.attrNames m.config)
else
builtins.trace "try to evaluate config ${lib.showVal config}."
false;
options' = opt.options or
(throw "Option `${showOption loc'}' has type optionSet but has no option attribute.");
coerce = x:
if builtins.isFunction x then x
else { config, ... }: { options = x; };
options = map coerce (flatten options');
f = tp:
if tp.name == "option set" then types.submodule options
else if tp.name == "attribute set of option sets" then types.attrsOf (types.submodule options)
else if tp.name == "list or attribute set of option sets" then types.loaOf (types.submodule options)
else if tp.name == "list of option sets" then types.listOf (types.submodule options)
else if tp.name == "null or option set" then types.nullOr (types.submodule options)
else tp;
in opt // { type = f (opt.type or types.unspecified); };
/* Properties. */
mkIf = condition: content:
{ _type = "if";
inherit condition content;
};
mkAssert = assertion: message: content:
mkIf
(if assertion then true else throw "\nFailed assertion: ${message}")
content;
mkMerge = contents:
{ _type = "merge";
inherit contents;
};
mkOverride = priority: content:
{ _type = "override";
inherit priority content;
};
mkOptionDefault = mkOverride 1001;
mkDefault = mkOverride 1000;
mkForce = mkOverride 50;
mkFixStrictness = id; # obsolete, no-op
# FIXME: Add mkOrder back in. It's not currently used anywhere in
# NixOS, but it should be useful.
}

46
lib/options.nix
View file

@ -2,12 +2,10 @@
let lib = import ./default.nix; in
with { inherit (builtins) head length; };
with import ./trivial.nix;
with import ./lists.nix;
with import ./misc.nix;
with import ./attrsets.nix;
with import ./properties.nix;
rec {
@ -137,46 +135,6 @@ rec {
handleOptionSets
];
# Merge a list of options containning different field. This is useful to
# separate the merge & apply fields from the interface.
mergeOptionDecls = opts:
if opts == [] then {}
else if length opts == 1 then
let opt = head opts; in
if opt ? options then
opt // { options = toList opt.options; }
else
opt
else
fold (opt1: opt2:
lib.addErrorContext "opt1 = ${lib.showVal opt1}\nopt2 = ${lib.showVal opt2}" (
# You cannot merge if two options have the same field.
assert opt1 ? default -> ! opt2 ? default;
assert opt1 ? example -> ! opt2 ? example;
assert opt1 ? description -> ! opt2 ? description;
assert opt1 ? merge -> ! opt2 ? merge;
assert opt1 ? apply -> ! opt2 ? apply;
assert opt1 ? type -> ! opt2 ? type;
opt1 // opt2
// optionalAttrs (opt1 ? options || opt2 ? options) {
options =
(toList (opt1.options or []))
++ (toList (opt2.options or []));
}
// optionalAttrs (opt1 ? extraConfigs || opt2 ? extraConfigs) {
extraConfigs = opt1.extraConfigs or [] ++ opt2.extraConfigs or [];
}
// optionalAttrs (opt1 ? extraArgs || opt2 ? extraArgs) {
extraArgs = opt1.extraArgs or {} // opt2.extraArgs or {};
}
// optionalAttrs (opt1 ? individualExtraArgs || opt2 ? individualExtraArgs) {
individualExtraArgs = zipAttrsWith (name: values:
if length values == 1 then head values else (head values // (head (tail values)))
) [ (opt1.individualExtraArgs or {}) (opt2.individualExtraArgs or {}) ];
}
)) {} opts;
# !!! This function will be removed because this can be done with the
# multiple option declarations.
addDefaultOptionValues = defs: opts: opts //
@ -285,6 +243,7 @@ rec {
else
[];
in
# FIXME: expensive (O(n^2)
[ docOption ] ++ subOptions ++ rest
) [] options;
@ -308,4 +267,7 @@ rec {
literalExample = text: { _type = "literalExample"; inherit text; };
/* Helper functions. */
showOption = concatStringsSep ".";
}

464
lib/properties.nix
View file

@ -1,464 +0,0 @@
# Nixpkgs/NixOS properties. Generalize the problem of delayable (not yet
# evaluable) properties like mkIf.
let lib = import ./default.nix; in
with { inherit (builtins) head tail; };
with import ./trivial.nix;
with import ./lists.nix;
with import ./misc.nix;
with import ./attrsets.nix;
rec {
inherit (lib) isType;
# Tell that nothing is defined. When properties are evaluated, this type
# is used to remove an entry. Thus if your property evaluation semantic
# implies that you have to mute the content of an attribute, then your
# property should produce this value.
isNotdef = isType "notdef";
mkNotdef = {_type = "notdef";};
# General property type, it has a property attribute and a content
# attribute. The property attribute refers to an attribute set which
# contains a _type attribute and a list of functions which are used to
# evaluate this property. The content attribute is used to stack properties
# on top of each other.
#
# The optional functions which may be contained in the property attribute
# are:
# - onDelay: run on a copied property.
# - onGlobalDelay: run on all copied properties.
# - onEval: run on an evaluated property.
# - onGlobalEval: run on a list of property stack on top of their values.
isProperty = isType "property";
mkProperty = p@{property, content, ...}: p // {
_type = "property";
};
# Go through the stack of properties and apply the function `op' on all
# property and call the function `nul' on the final value which is not a
# property. The stack is traversed in reversed order. The `op' function
# should expect a property with a content which have been modified.
#
# Warning: The `op' function expects only one argument in order to avoid
# calls to mkProperties as the argument is already a valid property which
# contains the result of the folding inside the content attribute.
foldProperty = op: nul: attrs:
if isProperty attrs then
op (attrs // {
content = foldProperty op nul attrs.content;
})
else
nul attrs;
# Simple function which can be used as the `op' argument of the
# foldProperty function. Properties that you don't want to handle can be
# ignored with the `id' function. `isSearched' is a function which should
# check the type of a property and return a boolean value. `thenFun' and
# `elseFun' are functions which behave as the `op' argument of the
# foldProperty function.
foldFilter = isSearched: thenFun: elseFun: attrs:
if isSearched attrs.property then
thenFun attrs
else
elseFun attrs;
# Move properties from the current attribute set to the attribute
# contained in this attribute set. This trigger property handlers called
# `onDelay' and `onGlobalDelay'.
delayPropertiesWithIter = iter: path: attrs:
let cleanAttrs = rmProperties attrs; in
if isProperty attrs then
iter (a: v:
lib.addErrorContext "while moving properties on the attribute `${a}':" (
triggerPropertiesGlobalDelay a (
triggerPropertiesDelay a (
copyProperties attrs v
)))) path cleanAttrs
else
attrs;
delayProperties = # implicit attrs argument.
let
# mapAttrs except that it also recurse into potential mkMerge
# functions. This may cause a strictness issue because looking the
# type of a string implies evaluating it.
iter = fun: path: value:
lib.mapAttrs (attr: val:
if isProperty val && isMerge val.property then
val // { content = map (fun attr) val.content; }
else
fun attr val
) value;
in
delayPropertiesWithIter iter "";
# Call onDelay functions.
triggerPropertiesDelay = name: attrs:
let
callOnDelay = p@{property, ...}:
if property ? onDelay then
property.onDelay name p
else
p;
in
foldProperty callOnDelay id attrs;
# Call onGlobalDelay functions.
triggerPropertiesGlobalDelay = name: attrs:
let
globalDelayFuns = uniqListExt {
getter = property: property._type;
inputList = foldProperty (p@{property, content, ...}:
if property ? onGlobalDelay then
[ property ] ++ content
else
content
) (a: []) attrs;
};
callOnGlobalDelay = property: content:
property.onGlobalDelay name content;
in
fold callOnGlobalDelay attrs globalDelayFuns;
# Expect a list of values which may have properties and return the same
# list of values where all properties have been evaluated and where all
# ignored values are removed. This trigger property handlers called
# `onEval' and `onGlobalEval'.
evalProperties = valList:
if valList != [] then
filter (x: !isNotdef x) (
triggerPropertiesGlobalEval (
evalLocalProperties valList
)
)
else
valList;
evalLocalProperties = valList:
filter (x: !isNotdef x) (
map triggerPropertiesEval valList
);
# Call onEval function
triggerPropertiesEval = val:
foldProperty (p@{property, ...}:
if property ? onEval then
property.onEval p
else
p
) id val;
# Call onGlobalEval function
triggerPropertiesGlobalEval = valList:
let
globalEvalFuns = uniqListExt {
getter = property: property._type;
inputList =
fold (attrs: list:
foldProperty (p@{property, content, ...}:
if property ? onGlobalEval then
[ property ] ++ content
else
content
) (a: list) attrs
) [] valList;
};
callOnGlobalEval = property: valList: property.onGlobalEval valList;
in
fold callOnGlobalEval valList globalEvalFuns;
# Remove all properties on top of a value and return the value.
rmProperties =
foldProperty (p@{content, ...}: content) id;
# Copy properties defined on a value on another value.
copyProperties = attrs: newAttrs:
foldProperty id (x: newAttrs) attrs;
/* Merge. */
# Create "merge" statement which is skipped by the delayProperty function
# and interpreted by the underlying system using properties (modules).
# Create a "Merge" property which only contains a condition.
isMerge = isType "merge";
mkMerge = content: mkProperty {
property = {
_type = "merge";
onDelay = name: val: throw "mkMerge is not the first of the list of properties.";
onEval = val: throw "mkMerge is not allowed on option definitions.";
};
inherit content;
};
/* If. ThenElse. Always. */
# create "if" statement that can be delayed on sets until a "then-else" or
# "always" set is reached. When an always set is reached the condition
# is ignore.
# Create a "If" property which only contains a condition.
isIf = isType "if";
mkIf = condition: content: mkProperty {
property = {
_type = "if";
onGlobalDelay = onIfGlobalDelay;
onEval = onIfEval;
inherit condition;
};
inherit content;
};
mkAssert = assertion: message: content:
mkIf
(if assertion then true else throw "\nFailed assertion: ${message}")
content;
# Evaluate the "If" statements when either "ThenElse" or "Always"
# statement is encountered. Otherwise it removes multiple If statements and
# replaces them by one "If" statement where the condition is the list of all
# conditions joined with a "and" operation.
onIfGlobalDelay = name: content:
let
# extract if statements and non-if statements and repectively put them
# in the attribute list and attrs.
ifProps =
foldProperty
(foldFilter (p: isIf p)
# then, push the condition inside the list list
(p@{property, content, ...}:
{ inherit (content) attrs;
list = [property] ++ content.list;
}
)
# otherwise, add the propertie.
(p@{property, content, ...}:
{ inherit (content) list;
attrs = p // { content = content.attrs; };
}
)
)
(attrs: { list = []; inherit attrs; })
content;
# compute the list of if statements.
evalIf = content: condition: list:
if list == [] then
mkIf condition content
else
let p = head list; in
evalIf content (condition && p.condition) (tail list);
in
evalIf ifProps.attrs true ifProps.list;
# Evaluate the condition of the "If" statement to either get the value or
# to ignore the value.
onIfEval = p@{property, content, ...}:
if property.condition then
content
else
mkNotdef;
/* mkOverride */
# Create an "Override" statement which allow the user to define
# priorities between values. The default priority is 100. The lowest
# priorities are kept. The template argument must reproduce the same
# attribute set hierarchy to override leaves of the hierarchy.
isOverride = isType "override";
mkOverrideTemplate = priority: template: content: mkProperty {
property = {
_type = "override";
onDelay = onOverrideDelay;
onGlobalEval = onOverrideGlobalEval;
inherit priority template;
};
inherit content;
};
# Like mkOverrideTemplate, but without the template argument.
mkOverride = priority: content: mkOverrideTemplate priority {} content;
# Sugar to override the default value of the option by making a new
# default value based on the configuration.
mkDefaultValue = mkOverride 1000;
mkDefault = mkOverride 1000;
mkForce = mkOverride 50;
mkStrict = mkOverride 0;
# Make the template traversal in function of the property traversal. If
# the template define a non-empty attribute set, then the property is
# copied only on all mentionned attributes inside the template.
# Otherwise, the property is kept on all sub-attribute definitions.
onOverrideDelay = name: p@{property, content, ...}:
let inherit (property) template; in
if isAttrs template && template != {} then
if hasAttr name template then
p // {
property = p.property // {
template = builtins.getAttr name template;
};
}
# Do not override the attribute \name\
else
content
# Override values defined inside the attribute \name\.
else
p;
# Keep values having lowest priority numbers only throwing away those having
# a higher priority assigned.
onOverrideGlobalEval = valList:
let
defaultPrio = 100;
inherit (builtins) lessThan;
getPrioVal =
foldProperty
(foldFilter isOverride
(p@{property, content, ...}:
if content ? priority && lessThan content.priority property.priority then
content
else
content // {
inherit (property) priority;
}
)
(p@{property, content, ...}:
content // {
value = p // { content = content.value; };
}
)
) (value: { inherit value; });
addDefaultPrio = x:
if x ? priority then x
else x // { priority = defaultPrio; };
prioValList = map (x: addDefaultPrio (getPrioVal x)) valList;
higherPrio =
if prioValList == [] then
defaultPrio
else
fold (x: min:
if lessThan x.priority min then
x.priority
else
min
) (head prioValList).priority (tail prioValList);
in
map (x:
if x.priority == higherPrio then
x.value
else
mkNotdef
) prioValList;
/* mkOrder */
# Order definitions based on there index value. This property is useful
# when the result of the merge function depends on the order on the
# initial list. (e.g. concatStrings) Definitions are ordered based on
# their rank. The lowest ranked definition would be the first to element
# of the list used by the merge function. And the highest ranked
# definition would be the last. Definitions which does not have any rank
# value have the default rank of 100.
isOrder = isType "order";
mkOrder = rank: content: mkProperty {
property = {
_type = "order";
onGlobalEval = onOrderGlobalEval;
inherit rank;
};
inherit content;
};
mkHeader = mkOrder 10;
mkFooter = mkOrder 1000;
# Fetch the rank of each definition (add the default rank is none) and
# sort them based on their ranking.
onOrderGlobalEval = valList:
let
defaultRank = 100;
inherit (builtins) lessThan;
getRankVal =
foldProperty
(foldFilter isOrder
(p@{property, content, ...}:
if content ? rank then
content
else
content // {
inherit (property) rank;
}
)
(p@{property, content, ...}:
content // {
value = p // { content = content.value; };
}
)
) (value: { inherit value; });
addDefaultRank = x:
if x ? rank then x
else x // { rank = defaultRank; };
rankValList = map (x: addDefaultRank (getRankVal x)) valList;
cmp = x: y:
builtins.lessThan x.rank y.rank;
in
map (x: x.value) (sort cmp rankValList);
/* mkFixStrictness */
# This is a hack used to restore laziness on some option definitions.
# Some option definitions are evaluated when they are not used. This
# error is caused by the strictness of type checking builtins. Builtins
# like 'isAttrs' are too strict because they have to evaluate their
# arguments to check if the type is correct. This evaluation, cause the
# strictness of properties.
#
# Properties can be stacked on top of each other. The stackability of
# properties on top of the option definition is nice for user manipulation
# but require to check if the content of the property is not another
# property. Such testing implies to verify if this is an attribute set
# and if it possess the type 'property'. (see isProperty & typeOf/isType)
#
# To avoid strict evaluation of option definitions, 'mkFixStrictness' is
# introduced. This property protects an option definition by replacing
# the base of the stack of properties by 'mkNotDef', when this property is
# evaluated it returns the original definition.
#
# This property is useful over any elements which depends on options which
# are raising errors when they get evaluated without the proper settings.
#
# Plain list and attribute set are lazy structures, which means that the
# container gets evaluated but not the content. Thus, using this property
# on top of plain list or attribute set is pointless.
#
# This is a Hack, you should avoid it!
# This property has a long name because you should avoid it.
isFixStrictness = attrs: (typeOf attrs) == "fix-strictness";
mkFixStrictness = value:
mkProperty {
property = {
_type = "fix-strictness";
onEval = p: value;
};
content = mkNotdef;
};
}

144
lib/types.nix
View file

@ -3,10 +3,11 @@
let lib = import ./default.nix; in
with import ./lists.nix;
with import ./attrsets.nix;
with import ./options.nix;
with import ./trivial.nix;
with lib.lists;
with lib.attrsets;
with lib.options;
with lib.trivial;
with lib.modules;
rec {
@ -20,48 +21,43 @@ rec {
# name (name of the type)
# check (check the config value. Before returning false it should trace the bad value eg using traceValIfNot)
# check (check the config value)
# merge (default merge function)
# iter (iterate on all elements contained in this type)
# fold (fold all elements contained in this type)
# hasOptions (boolean: whatever this option contains an option set)
# delayOnGlobalEval (boolean: should properties go through the evaluation of this option)
# docPath (path concatenated to the option name contained in the option set)
isOptionType = isType "option-type";
mkOptionType =
{ name
, check ? (x: true)
, merge ? mergeDefaultOption
# Handle complex structure types.
, iter ? (f: path: v: f path v)
, fold ? (op: nul: v: op v nul)
, merge' ? args: merge
, docPath ? lib.id
# If the type can contains option sets.
, hasOptions ? false
, delayOnGlobalEval ? false
}:
{ _type = "option-type";
inherit name check merge iter fold docPath hasOptions delayOnGlobalEval;
inherit name check merge merge' docPath;
};
types = rec {
unspecified = mkOptionType {
name = "unspecified";
};
bool = mkOptionType {
name = "boolean";
check = lib.traceValIfNot builtins.isBool;
check = builtins.isBool;
merge = fold lib.or false;
};
int = mkOptionType {
name = "integer";
check = lib.traceValIfNot builtins.isInt;
check = builtins.isInt;
};
string = mkOptionType {
name = "string";
check = lib.traceValIfNot builtins.isString;
check = builtins.isString;
merge = lib.concatStrings;
};
@ -69,7 +65,7 @@ rec {
# configuration file contents.
lines = mkOptionType {
name = "string";
check = lib.traceValIfNot builtins.isString;
check = builtins.isString;
merge = lib.concatStringsSep "\n";
};
@ -81,48 +77,37 @@ rec {
attrs = mkOptionType {
name = "attribute set";
check = lib.traceValIfNot isAttrs;
check = isAttrs;
merge = fold lib.mergeAttrs {};
};
# derivation is a reserved keyword.
package = mkOptionType {
name = "derivation";
check = lib.traceValIfNot isDerivation;
check = isDerivation;
};
path = mkOptionType {
name = "path";
# Hacky: there is no ‘isPath’ primop.
check = lib.traceValIfNot (x: builtins.unsafeDiscardStringContext (builtins.substring 0 1 (toString x)) == "/");
check = x: builtins.unsafeDiscardStringContext (builtins.substring 0 1 (toString x)) == "/";
};
# drop this in the future:
list = builtins.trace "types.list is deprecated, use types.listOf instead" types.listOf;
list = builtins.trace "types.list is deprecated; use types.listOf instead" types.listOf;
listOf = elemType: mkOptionType {
listOf = elemType: mkOptionType {
name = "list of ${elemType.name}s";
check = value: lib.traceValIfNot isList value && all elemType.check value;
merge = concatLists;
iter = f: path: list: map (elemType.iter f (path + ".*")) list;
fold = op: nul: list: lib.fold (e: l: elemType.fold op l e) nul list;
check = value: isList value && all elemType.check value;
merge = defs: map (def: elemType.merge [def]) (concatLists defs);
docPath = path: elemType.docPath (path + ".*");
inherit (elemType) hasOptions;
# You cannot define multiple configurations of one entity, therefore
# no reason justify to delay properties inside list elements.
delayOnGlobalEval = false;
};
attrsOf = elemType: mkOptionType {
name = "attribute set of ${elemType.name}s";
check = x: lib.traceValIfNot isAttrs x
&& all elemType.check (lib.attrValues x);
merge = lib.zipAttrsWith (name: elemType.merge);
iter = f: path: set: lib.mapAttrs (name: elemType.iter f (path + "." + name)) set;
fold = op: nul: set: fold (e: l: elemType.fold op l e) nul (lib.attrValues set);
check = x: isAttrs x && all elemType.check (lib.attrValues x);
merge = lib.zipAttrsWith (name: elemType.merge' { inherit name; });
docPath = path: elemType.docPath (path + ".<name>");
inherit (elemType) hasOptions delayOnGlobalEval;
};
# List or attribute set of ...
@ -143,26 +128,13 @@ rec {
check = x:
if isList x then listOnly.check x
else if isAttrs x then attrOnly.check x
else lib.traceValIfNot (x: false) x;
## The merge function returns an attribute set
merge = defs:
attrOnly.merge (imap convertIfList defs);
iter = f: path: def:
if isList def then listOnly.iter f path def
else if isAttrs def then attrOnly.iter f path def
else throw "Unexpected value";
fold = op: nul: def:
if isList def then listOnly.fold op nul def
else if isAttrs def then attrOnly.fold op nul def
else throw "Unexpected value";
else false;
merge = defs: attrOnly.merge (imap convertIfList defs);
docPath = path: elemType.docPath (path + ".<name?>");
inherit (elemType) hasOptions delayOnGlobalEval;
}
;
};
uniq = elemType: mkOptionType {
inherit (elemType) name check iter fold docPath hasOptions;
inherit (elemType) name check docPath;
merge = list:
if length list == 1 then
head list
@ -171,54 +143,46 @@ rec {
};
none = elemType: mkOptionType {
inherit (elemType) name check iter fold docPath hasOptions;
inherit (elemType) name check docPath;
merge = list:
throw "No definitions are allowed for this option.";
};
nullOr = elemType: mkOptionType {
inherit (elemType) name merge docPath hasOptions;
inherit (elemType) docPath;
name = "null or ${elemType.name}";
check = x: builtins.isNull x || elemType.check x;
iter = f: path: v: if v == null then v else elemType.iter f path v;
fold = op: nul: v: if v == null then nul else elemType.fold op nul v;
merge = defs:
if all isNull defs then null
else if any isNull defs then
throw "Some but not all values are null."
else elemType.merge defs;
};
functionTo = elemType: mkOptionType {
name = "function that evaluates to a(n) ${elemType.name}";
check = lib.traceValIfNot builtins.isFunction;
check = builtins.isFunction;
merge = fns:
args: elemType.merge (map (fn: fn args) fns);
# These are guesses, I don't fully understand iter, fold, delayOnGlobalEval
iter = f: path: v:
args: elemType.iter f path (v args);
fold = op: nul: v:
args: elemType.fold op nul (v args);
inherit (elemType) delayOnGlobalEval;
hasOptions = false;
};
# usually used with listOf, attrsOf, loaOf like this:
# users = mkOption {
# type = loaOf optionSet;
#
# # you can omit the list if there is one element only
# options = [ {
# name = mkOption {
# description = "name of the user"
# ...
# };
# # more options here
# } { more options } ];
# }
# TODO: !!! document passing options as an argument to optionSet,
# deprecate the current approach.
optionSet = mkOptionType {
name = "option set";
# merge is done in "options.nix > addOptionMakeUp > handleOptionSets"
merge = lib.id;
submodule = opts: mkOptionType rec {
name = "submodule";
check = x: isAttrs x || builtins.isFunction x;
hasOptions = true;
delayOnGlobalEval = true;
# FIXME: make error messages include the parent attrpath.
merge = merge' {};
merge' = args: defs:
let
coerce = def: if builtins.isFunction def then def else { config = def; };
modules = (toList opts) ++ map coerce defs;
in (evalModules modules args).config;
};
# Obsolete alternative to configOf. It takes its option
# declarations from the ‘options’ attribute of containing option
# declaration.
optionSet = mkOptionType {
name = /* builtins.trace "types.optionSet is deprecated; use types.submodule instead" */ "option set";
};
};

13
nixos/lib/eval-config.nix
View file

@ -19,11 +19,9 @@ rec {
# Merge the option definitions in all modules, forming the full
# system configuration. It's not checked for undeclared options.
systemModule =
pkgs.lib.fixMergeModules configComponents extraArgs;
pkgs.lib.evalModules configComponents extraArgs;
optionDefinitions = systemModule.config;
optionDeclarations = systemModule.options;
inherit (systemModule) options;
config = systemModule.config;
# These are the extra arguments passed to every module. In
# particular, Nixpkgs is passed through the "pkgs" argument.
@ -56,16 +54,11 @@ rec {
# define nixpkgs.config, so it's pointless to evaluate them.
baseModules = [ ../modules/misc/nixpkgs.nix ];
pkgs = import ./nixpkgs.nix { system = system_; config = {}; };
}).optionDefinitions.nixpkgs;
}).config.nixpkgs;
in
{
inherit system;
inherit (nixpkgsOptions) config;
});
# Optionally check wether all config values have corresponding
# option declarations.
config =
assert optionDefinitions.environment.checkConfigurationOptions -> pkgs.lib.checkModule "" systemModule;
systemModule.config;
}

9
nixos/modules/config/shells-environment.nix
View file

@ -26,11 +26,10 @@ in
type = types.attrsOf (mkOptionType {
name = "a string or a list of strings";
merge = xs:
let xs' = evalProperties xs; in
if isList (head xs') then concatLists xs'
else if builtins.lessThan 1 (length xs') then abort "variable in ‘environment.variables’ has multiple values"
else if !builtins.isString (head xs') then abort "variable in ‘environment.variables’ does not have a string value"
else head xs';
if isList (head xs) then concatLists xs
else if builtins.lessThan 1 (length xs) then abort "variable in ‘environment.variables’ has multiple values"
else if !builtins.isString (head xs) then abort "variable in ‘environment.variables’ does not have a string value"
else head xs;
});
apply = mapAttrs (n: v: if isList v then concatStringsSep ":" v else v);
};

2
nixos/modules/system/activation/activation-script.nix
View file

@ -52,7 +52,7 @@ in
idempotent and fast.
'';
merge = mergeTypedOption "script" builtins.isAttrs (fold mergeAttrs {});
type = types.attrsOf types.unspecified; # FIXME
apply = set: {
script =