nixpkgs/lib/types.nix

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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;
with {inherit (import ./modules.nix) mergeDefinitions; };
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";
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check = isBool;
merge = mergeEqualOption;
};
int = mkOptionType {
name = "integer";
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check = isInt;
merge = mergeOneOption;
};
str = mkOptionType {
name = "string";
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check = isString;
merge = mergeOneOption;
};
# Merge multiple definitions by concatenating them (with the given
# separator between the values).
separatedString = sep: mkOptionType {
name = "string";
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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: foldl' (res: def: mergeAttrs res def.value) {};
};
# derivation is a reserved keyword.
package = mkOptionType {
name = "derivation";
check = x: isDerivation x || isStorePath x;
merge = loc: defs:
let res = mergeOneOption loc defs;
in if isDerivation res then res else toDerivation res;
};
path = mkOptionType {
name = "path";
# Hacky: there is no isPath primop.
check = x: 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':
(mergeDefinitions
(loc ++ ["[definition ${toString n}-entry ${toString m}]"])
elemType
[{ inherit (def) file; value = def'; }]
).optionalValue
) def.value) defs)));
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getSubOptions = prefix: elemType.getSubOptions (prefix ++ ["*"]);
getSubModules = elemType.getSubModules;
substSubModules = m: listOf (elemType.substSubModules m);
};
attrsOf = elemType: mkOptionType {
name = "attribute set of ${elemType.name}s";
check = isAttrs;
merge = loc: defs:
mapAttrs (n: v: v.value) (filterAttrs (n: v: v ? value) (zipAttrsWith (name: defs:
(mergeDefinitions (loc ++ [name]) elemType defs).optionalValue
)
# Push down position info.
(map (def: listToAttrs (mapAttrsToList (n: def':
{ name = n; value = { inherit (def) file; value = def'; }; }) def.value)) defs)));
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getSubOptions = prefix: elemType.getSubOptions (prefix ++ ["<name>"]);
getSubModules = elemType.getSubModules;
substSubModules = m: attrsOf (elemType.substSubModules m);
};
# List or attribute set of ...
loaOf = elemType:
let
convertIfList = defIdx: def:
if isList def.value then
{ inherit (def) file;
value = listToAttrs (
imap (elemIdx: elem:
{ name = elem.name or "unnamed-${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);
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getSubOptions = prefix: elemType.getSubOptions (prefix ++ ["<name?>"]);
getSubModules = elemType.getSubModules;
substSubModules = m: loaOf (elemType.substSubModules m);
};
uniq = elemType: mkOptionType {
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inherit (elemType) name check;
merge = mergeOneOption;
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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;
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getSubOptions = elemType.getSubOptions;
getSubModules = elemType.getSubModules;
substSubModules = m: nullOr (elemType.substSubModules m);
};
submodule = opts:
let
opts' = toList opts;
inherit (import ./modules.nix) evalModules;
in
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mkOptionType rec {
name = "submodule";
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check = x: isAttrs x || isFunction x;
merge = loc: defs:
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let
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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;
args.name = last loc;
prefix = loc;
}).config;
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getSubOptions = prefix: (evalModules
{ modules = opts'; inherit prefix;
# FIXME: hack to get shit to evaluate.
args = { name = ""; }; }).options;
getSubModules = opts';
substSubModules = m: submodule m;
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};
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enum = values: mkOptionType {
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name = "one of ${concatStringsSep ", " values}";
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check = flip elem values;
merge = mergeOneOption;
};
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either = t1: t2: mkOptionType {
name = "${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; };
};
}