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nixpkgs/lib/types.nix
Shea Levy 0a0a29fd0b Add comments about the module system interface
Ideally the module system could be configured pretty much completely by
the contents of the modules themselves, so add comments about avoiding
complicating it further and possibly removing now-redundant
configurability from the existing interface.
2015-03-12 23:42:57 +01:00

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# Definitions related to run-time type checking. Used in particular
# to type-check NixOS configurations.
with import ./lists.nix;
with import ./attrsets.nix;
with import ./options.nix;
with import ./trivial.nix;
with import ./strings.nix;
let
inherit (import ./modules.nix) mergeDefinitions;
in rec {
isType = type: x: (x._type or "") == type;
setType = typeName: value: value // {
_type = typeName;
};
isOptionType = isType "option-type";
mkOptionType =
{ # Human-readable representation of the type.
name
, # Function applied to each definition that should return true if
# its type-correct, false otherwise.
check ? (x: true)
, # Merge a list of definitions together into a single value.
# This function is called with two arguments: the location of
# the option in the configuration as a list of strings
# (e.g. ["boot" "loader "grub" "enable"]), and a list of
# definition values and locations (e.g. [ { file = "/foo.nix";
# value = 1; } { file = "/bar.nix"; value = 2 } ]).
merge ? mergeDefaultOption
, # Return a flat list of sub-options. Used to generate
# documentation.
getSubOptions ? prefix: {}
, # List of modules if any, or null if none.
getSubModules ? null
, # Function for building the same option type with a different list of
# modules.
substSubModules ? m: null
}:
{ _type = "option-type";
inherit name check merge getSubOptions getSubModules substSubModules;
};
types = rec {
unspecified = mkOptionType {
name = "unspecified";
};
bool = mkOptionType {
name = "boolean";
check = isBool;
merge = loc: fold (x: y: x.value || y) false;
};
int = mkOptionType {
name = "integer";
check = isInt;
merge = mergeOneOption;
};
str = mkOptionType {
name = "string";
check = isString;
merge = mergeOneOption;
};
# Merge multiple definitions by concatenating them (with the given
# separator between the values).
separatedString = sep: mkOptionType {
name = "string";
check = isString;
merge = loc: defs: concatStringsSep sep (getValues defs);
};
lines = separatedString "\n";
commas = separatedString ",";
envVar = separatedString ":";
# Deprecated; should not be used because it quietly concatenates
# strings, which is usually not what you want.
string = separatedString "";
attrs = mkOptionType {
name = "attribute set";
check = isAttrs;
merge = loc: fold (def: mergeAttrs def.value) {};
};
# derivation is a reserved keyword.
package = mkOptionType {
name = "derivation";
check = isDerivation;
merge = mergeOneOption;
};
path = mkOptionType {
name = "path";
# Hacky: there is no isPath primop.
check = x: builtins.unsafeDiscardStringContext (builtins.substring 0 1 (toString x)) == "/";
merge = mergeOneOption;
};
# drop this in the future:
list = builtins.trace "`types.list' is deprecated; use `types.listOf' instead" types.listOf;
listOf = elemType: mkOptionType {
name = "list of ${elemType.name}s";
check = isList;
merge = loc: defs:
map (x: x.value) (filter (x: x ? value) (concatLists (imap (n: def: imap (m: def':
let
inherit (mergeDefinitions (loc ++ ["[definition ${toString n}-entry ${toString m}]"])
elemType [{ inherit (def) file; value = def'; }]
) defsFinal mergedValue;
in if defsFinal == [] then {} else { value = mergedValue; }) def.value) defs)));
getSubOptions = prefix: elemType.getSubOptions (prefix ++ ["*"]);
getSubModules = elemType.getSubModules;
substSubModules = m: listOf (elemType.substSubModules m);
};
attrsOf = elemType: mkOptionType {
name = "attribute set of ${elemType.name}s";
check = isAttrs;
merge = loc: defs:
mapAttrs (n: v: v.value) (filterAttrs (n: v: v ? value) (zipAttrsWith (name: defs:
let
inherit (mergeDefinitions (loc ++ [name]) elemType defs)
defsFinal mergedValue;
in if defsFinal == [] then {} else { value = mergedValue; })
# Push down position info.
(map (def: listToAttrs (mapAttrsToList (n: def':
{ name = n; value = { inherit (def) file; value = def'; }; }) def.value)) defs)));
getSubOptions = prefix: elemType.getSubOptions (prefix ++ ["<name>"]);
getSubModules = elemType.getSubModules;
substSubModules = m: attrsOf (elemType.substSubModules m);
};
# List or attribute set of ...
loaOf = elemType:
let
convertIfList = defIdx: def:
if isList def.value then
{ inherit (def) file;
value = listToAttrs (
imap (elemIdx: elem:
{ name = elem.name or "unnamed-${toString defIdx}.${toString elemIdx}";
value = elem;
}) def.value);
}
else
def;
listOnly = listOf elemType;
attrOnly = attrsOf elemType;
in mkOptionType {
name = "list or attribute set of ${elemType.name}s";
check = x: isList x || isAttrs x;
merge = loc: defs: attrOnly.merge loc (imap convertIfList defs);
getSubOptions = prefix: elemType.getSubOptions (prefix ++ ["<name?>"]);
getSubModules = elemType.getSubModules;
substSubModules = m: loaOf (elemType.substSubModules m);
};
uniq = elemType: mkOptionType {
inherit (elemType) name check;
merge = mergeOneOption;
getSubOptions = elemType.getSubOptions;
getSubModules = elemType.getSubModules;
substSubModules = m: uniq (elemType.substSubModules m);
};
nullOr = elemType: mkOptionType {
name = "null or ${elemType.name}";
check = x: builtins.isNull x || elemType.check x;
merge = loc: defs:
let nrNulls = count (def: isNull def.value) defs; in
if nrNulls == length defs then null
else if nrNulls != 0 then
throw "The option `${showOption loc}' is defined both null and not null, in ${showFiles (getFiles defs)}."
else elemType.merge loc defs;
getSubOptions = elemType.getSubOptions;
getSubModules = elemType.getSubModules;
substSubModules = m: nullOr (elemType.substSubModules m);
};
submodule = opts:
let
opts' = toList opts;
inherit (import ./modules.nix) evalModules;
in
mkOptionType rec {
name = "submodule";
check = x: isAttrs x || isFunction x;
merge = loc: defs:
let
coerce = def: if isFunction def then def else { config = def; };
modules = opts' ++ map (def: { _file = def.file; imports = [(coerce def.value)]; }) defs;
in (evalModules {
inherit modules;
# !!! See comment about args in lib/modules.nix
args.name = last loc;
prefix = loc;
}).config;
getSubOptions = prefix: (evalModules
{ modules = opts'; inherit prefix;
# FIXME: hack to get shit to evaluate.
args = { name = ""; }; }).options;
getSubModules = opts';
substSubModules = m: submodule m;
};
enum = values: mkOptionType {
name = "one of ${concatStringsSep ", " values}";
check = flip elem values;
merge = mergeOneOption;
};
either = t1: t2: mkOptionType {
name = "${t1.name} or ${t2.name}";
check = x: t1.check x || t2.check x;
merge = mergeOneOption;
};
# 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";
};
# Augment the given type with an additional type check function.
addCheck = elemType: check: elemType // { check = x: elemType.check x && check x; };
};
}