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nixpkgs/lib/types.nix
Silvan Mosberger 48293bd6b6 lib/types: Make types.anything merge functions
Previously it would give an error if there were multiple function
definitions.
2021-10-02 16:37:22 +02:00

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# Definitions related to run-time type checking. Used in particular
# to type-check NixOS configurations.
{ lib }:
let
inherit (lib)
elem
flip
functionArgs
isAttrs
isBool
isDerivation
isFloat
isFunction
isInt
isList
isString
isStorePath
setFunctionArgs
toDerivation
toList
;
inherit (lib.lists)
all
concatLists
count
elemAt
filter
foldl'
head
imap1
last
length
tail
unique
;
inherit (lib.attrsets)
attrNames
filterAttrs
hasAttr
mapAttrs
optionalAttrs
zipAttrsWith
;
inherit (lib.options)
getFiles
getValues
mergeDefaultOption
mergeEqualOption
mergeOneOption
showFiles
showOption
;
inherit (lib.strings)
concatMapStringsSep
concatStringsSep
escapeNixString
isCoercibleToString
;
inherit (lib.trivial)
boolToString
;
inherit (lib.modules) mergeDefinitions;
outer_types =
rec {
isType = type: x: (x._type or "") == type;
setType = typeName: value: value // {
_type = typeName;
};
# Default type merging function
# takes two type functors and return the merged type
defaultTypeMerge = f: f':
let wrapped = f.wrapped.typeMerge f'.wrapped.functor;
payload = f.binOp f.payload f'.payload;
in
# cannot merge different types
if f.name != f'.name
then null
# simple types
else if (f.wrapped == null && f'.wrapped == null)
&& (f.payload == null && f'.payload == null)
then f.type
# composed types
else if (f.wrapped != null && f'.wrapped != null) && (wrapped != null)
then f.type wrapped
# value types
else if (f.payload != null && f'.payload != null) && (payload != null)
then f.type payload
else null;
# Default type functor
defaultFunctor = name: {
inherit name;
type = types.${name} or null;
wrapped = null;
payload = null;
binOp = a: b: null;
};
isOptionType = isType "option-type";
mkOptionType =
{ # Human-readable representation of the type, should be equivalent to
# the type function name.
name
, # Description of the type, defined recursively by embedding the wrapped type if any.
description ? null
, # 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
, # Whether this type has a value representing nothingness. If it does,
# this should be a value of the form { value = <the nothing value>; }
# If it doesn't, this should be {}
# This may be used when a value is required for `mkIf false`. This allows the extra laziness in e.g. `lazyAttrsOf`.
emptyValue ? {}
, # 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
, # Function that merge type declarations.
# internal, takes a functor as argument and returns the merged type.
# returning null means the type is not mergeable
typeMerge ? defaultTypeMerge functor
, # The type functor.
# internal, representation of the type as an attribute set.
# name: name of the type
# type: type function.
# wrapped: the type wrapped in case of compound types.
# payload: values of the type, two payloads of the same type must be
# combinable with the binOp binary operation.
# binOp: binary operation that merge two payloads of the same type.
functor ? defaultFunctor name
, # The deprecation message to display when this type is used by an option
# If null, the type isn't deprecated
deprecationMessage ? null
, # The types that occur in the definition of this type. This is used to
# issue deprecation warnings recursively. Can also be used to reuse
# nested types
nestedTypes ? {}
}:
{ _type = "option-type";
inherit name check merge emptyValue getSubOptions getSubModules substSubModules typeMerge functor deprecationMessage nestedTypes;
description = if description == null then name else description;
};
# When adding new types don't forget to document them in
# nixos/doc/manual/development/option-types.xml!
types = rec {
anything = mkOptionType {
name = "anything";
description = "anything";
check = value: true;
merge = loc: defs:
let
getType = value:
if isAttrs value && isCoercibleToString value
then "stringCoercibleSet"
else builtins.typeOf value;
# Returns the common type of all definitions, throws an error if they
# don't have the same type
commonType = foldl' (type: def:
if getType def.value == type
then type
else throw "The option `${showOption loc}' has conflicting option types in ${showFiles (getFiles defs)}"
) (getType (head defs).value) defs;
mergeFunction = {
# Recursively merge attribute sets
set = (attrsOf anything).merge;
# Safe and deterministic behavior for lists is to only accept one definition
# listOf only used to apply mkIf and co.
list =
if length defs > 1
then throw "The option `${showOption loc}' has conflicting definitions, in ${showFiles (getFiles defs)}."
else (listOf anything).merge;
# This is the type of packages, only accept a single definition
stringCoercibleSet = mergeOneOption;
lambda = loc: defs: arg: anything.merge
(loc ++ [ "<function body>" ])
(map (def: {
file = def.file;
value = def.value arg;
}) defs);
# Otherwise fall back to only allowing all equal definitions
}.${commonType} or mergeEqualOption;
in mergeFunction loc defs;
};
unspecified = mkOptionType {
name = "unspecified";
};
bool = mkOptionType {
name = "bool";
description = "boolean";
check = isBool;
merge = mergeEqualOption;
};
int = mkOptionType {
name = "int";
description = "signed integer";
check = isInt;
merge = mergeEqualOption;
};
# Specialized subdomains of int
ints =
let
betweenDesc = lowest: highest:
"${toString lowest} and ${toString highest} (both inclusive)";
between = lowest: highest:
assert lib.assertMsg (lowest <= highest)
"ints.between: lowest must be smaller than highest";
addCheck int (x: x >= lowest && x <= highest) // {
name = "intBetween";
description = "integer between ${betweenDesc lowest highest}";
};
ign = lowest: highest: name: docStart:
between lowest highest // {
inherit name;
description = docStart + "; between ${betweenDesc lowest highest}";
};
unsign = bit: range: ign 0 (range - 1)
"unsignedInt${toString bit}" "${toString bit} bit unsigned integer";
sign = bit: range: ign (0 - (range / 2)) (range / 2 - 1)
"signedInt${toString bit}" "${toString bit} bit signed integer";
in {
/* An int with a fixed range.
*
* Example:
* (ints.between 0 100).check (-1)
* => false
* (ints.between 0 100).check (101)
* => false
* (ints.between 0 0).check 0
* => true
*/
inherit between;
unsigned = addCheck types.int (x: x >= 0) // {
name = "unsignedInt";
description = "unsigned integer, meaning >=0";
};
positive = addCheck types.int (x: x > 0) // {
name = "positiveInt";
description = "positive integer, meaning >0";
};
u8 = unsign 8 256;
u16 = unsign 16 65536;
# the biggest int Nix accepts is 2^63 - 1 (9223372036854775808)
# the smallest int Nix accepts is -2^63 (-9223372036854775807)
u32 = unsign 32 4294967296;
# u64 = unsign 64 18446744073709551616;
s8 = sign 8 256;
s16 = sign 16 65536;
s32 = sign 32 4294967296;
};
# Alias of u16 for a port number
port = ints.u16;
float = mkOptionType {
name = "float";
description = "floating point number";
check = isFloat;
merge = mergeEqualOption;
};
str = mkOptionType {
name = "str";
description = "string";
check = isString;
merge = mergeEqualOption;
};
nonEmptyStr = mkOptionType {
name = "nonEmptyStr";
description = "non-empty string";
check = x: str.check x && builtins.match "[ \t\n]*" x == null;
inherit (str) merge;
};
strMatching = pattern: mkOptionType {
name = "strMatching ${escapeNixString pattern}";
description = "string matching the pattern ${pattern}";
check = x: str.check x && builtins.match pattern x != null;
inherit (str) merge;
};
# Merge multiple definitions by concatenating them (with the given
# separator between the values).
separatedString = sep: mkOptionType rec {
name = "separatedString";
description = if sep == ""
then "Concatenated string" # for types.string.
else "strings concatenated with ${builtins.toJSON sep}"
;
check = isString;
merge = loc: defs: concatStringsSep sep (getValues defs);
functor = (defaultFunctor name) // {
payload = sep;
binOp = sepLhs: sepRhs:
if sepLhs == sepRhs then sepLhs
else null;
};
};
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 "" // {
name = "string";
deprecationMessage = "See https://github.com/NixOS/nixpkgs/pull/66346 for better alternative types.";
};
attrs = mkOptionType {
name = "attrs";
description = "attribute set";
check = isAttrs;
merge = loc: foldl' (res: def: res // def.value) {};
emptyValue = { value = {}; };
};
# derivation is a reserved keyword.
package = mkOptionType {
name = "package";
check = x: isDerivation x || isStorePath x;
merge = loc: defs:
let res = mergeOneOption loc defs;
in if isDerivation res then res else toDerivation res;
};
shellPackage = package // {
check = x: isDerivation x && hasAttr "shellPath" x;
};
path = mkOptionType {
name = "path";
check = x: isCoercibleToString x && builtins.substring 0 1 (toString x) == "/";
merge = mergeEqualOption;
};
listOf = elemType: mkOptionType rec {
name = "listOf";
description = "list of ${elemType.description}s";
check = isList;
merge = loc: defs:
map (x: x.value) (filter (x: x ? value) (concatLists (imap1 (n: def:
imap1 (m: def':
(mergeDefinitions
(loc ++ ["[definition ${toString n}-entry ${toString m}]"])
elemType
[{ inherit (def) file; value = def'; }]
).optionalValue
) def.value
) defs)));
emptyValue = { value = {}; };
getSubOptions = prefix: elemType.getSubOptions (prefix ++ ["*"]);
getSubModules = elemType.getSubModules;
substSubModules = m: listOf (elemType.substSubModules m);
functor = (defaultFunctor name) // { wrapped = elemType; };
nestedTypes.elemType = elemType;
};
nonEmptyListOf = elemType:
let list = addCheck (types.listOf elemType) (l: l != []);
in list // {
description = "non-empty " + list.description;
# Note: emptyValue is left as is, because another module may define an element.
};
attrsOf = elemType: mkOptionType rec {
name = "attrsOf";
description = "attribute set of ${elemType.description}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: mapAttrs (n: v: { inherit (def) file; value = v; }) def.value) defs)));
emptyValue = { value = {}; };
getSubOptions = prefix: elemType.getSubOptions (prefix ++ ["<name>"]);
getSubModules = elemType.getSubModules;
substSubModules = m: attrsOf (elemType.substSubModules m);
functor = (defaultFunctor name) // { wrapped = elemType; };
nestedTypes.elemType = elemType;
};
# A version of attrsOf that's lazy in its values at the expense of
# conditional definitions not working properly. E.g. defining a value with
# `foo.attr = mkIf false 10`, then `foo ? attr == true`, whereas with
# attrsOf it would correctly be `false`. Accessing `foo.attr` would throw an
# error that it's not defined. Use only if conditional definitions don't make sense.
lazyAttrsOf = elemType: mkOptionType rec {
name = "lazyAttrsOf";
description = "lazy attribute set of ${elemType.description}s";
check = isAttrs;
merge = loc: defs:
zipAttrsWith (name: defs:
let merged = mergeDefinitions (loc ++ [name]) elemType defs;
# mergedValue will trigger an appropriate error when accessed
in merged.optionalValue.value or elemType.emptyValue.value or merged.mergedValue
)
# Push down position info.
(map (def: mapAttrs (n: v: { inherit (def) file; value = v; }) def.value) defs);
emptyValue = { value = {}; };
getSubOptions = prefix: elemType.getSubOptions (prefix ++ ["<name>"]);
getSubModules = elemType.getSubModules;
substSubModules = m: lazyAttrsOf (elemType.substSubModules m);
functor = (defaultFunctor name) // { wrapped = elemType; };
nestedTypes.elemType = elemType;
};
# TODO: drop this in the future:
loaOf = elemType: types.attrsOf elemType // {
name = "loaOf";
deprecationMessage = "Mixing lists with attribute values is no longer"
+ " possible; please use `types.attrsOf` instead. See"
+ " https://github.com/NixOS/nixpkgs/issues/1800 for the motivation.";
nestedTypes.elemType = elemType;
};
# Value of given type but with no merging (i.e. `uniq list`s are not concatenated).
uniq = elemType: mkOptionType rec {
name = "uniq";
inherit (elemType) description check;
merge = mergeOneOption;
emptyValue = elemType.emptyValue;
getSubOptions = elemType.getSubOptions;
getSubModules = elemType.getSubModules;
substSubModules = m: uniq (elemType.substSubModules m);
functor = (defaultFunctor name) // { wrapped = elemType; };
nestedTypes.elemType = elemType;
};
# Null or value of ...
nullOr = elemType: mkOptionType rec {
name = "nullOr";
description = "null or ${elemType.description}";
check = x: x == null || elemType.check x;
merge = loc: defs:
let nrNulls = count (def: def.value == null) defs; in
if nrNulls == length defs then null
else if nrNulls != 0 then
throw "The option `${showOption loc}` is defined both null and not null, in ${showFiles (getFiles defs)}."
else elemType.merge loc defs;
emptyValue = { value = null; };
getSubOptions = elemType.getSubOptions;
getSubModules = elemType.getSubModules;
substSubModules = m: nullOr (elemType.substSubModules m);
functor = (defaultFunctor name) // { wrapped = elemType; };
nestedTypes.elemType = elemType;
};
functionTo = elemType: mkOptionType {
name = "functionTo";
description = "function that evaluates to a(n) ${elemType.name}";
check = isFunction;
merge = loc: defs:
fnArgs: (mergeDefinitions (loc ++ [ "[function body]" ]) elemType (map (fn: { inherit (fn) file; value = fn.value fnArgs; }) defs)).mergedValue;
getSubOptions = elemType.getSubOptions;
getSubModules = elemType.getSubModules;
substSubModules = m: functionTo (elemType.substSubModules m);
};
# A submodule (like typed attribute set). See NixOS manual.
submodule = modules: submoduleWith {
shorthandOnlyDefinesConfig = true;
modules = toList modules;
};
submoduleWith =
{ modules
, specialArgs ? {}
, shorthandOnlyDefinesConfig ? false
}@attrs:
let
inherit (lib.modules) evalModules;
coerce = unify: value: if isFunction value
then setFunctionArgs (args: unify (value args)) (functionArgs value)
else unify (if shorthandOnlyDefinesConfig then { config = value; } else value);
allModules = defs: modules ++ imap1 (n: { value, file }:
if isAttrs value || isFunction value then
# Annotate the value with the location of its definition for better error messages
coerce (lib.modules.unifyModuleSyntax file "${toString file}-${toString n}") value
else value
) defs;
freeformType = (evalModules {
inherit modules specialArgs;
args.name = "name";
})._module.freeformType;
in
mkOptionType rec {
name = "submodule";
description = freeformType.description or name;
check = x: isAttrs x || isFunction x || path.check x;
merge = loc: defs:
(evalModules {
modules = allModules defs;
inherit specialArgs;
args.name = last loc;
prefix = loc;
}).config;
emptyValue = { value = {}; };
getSubOptions = prefix: (evalModules
{ inherit modules prefix specialArgs;
# This is a work-around due to the fact that some sub-modules,
# such as the one included in an attribute set, expects a "args"
# attribute to be given to the sub-module. As the option
# evaluation does not have any specific attribute name, we
# provide a default one for the documentation.
#
# This is mandatory as some option declaration might use the
# "name" attribute given as argument of the submodule and use it
# as the default of option declarations.
#
# Using lookalike unicode single angle quotation marks because
# of the docbook transformation the options receive. In all uses
# &gt; and &lt; wouldn't be encoded correctly so the encoded values
# would be used, and use of `<` and `>` would break the XML document.
# It shouldn't cause an issue since this is cosmetic for the manual.
args.name = "name";
}).options // optionalAttrs (freeformType != null) {
# Expose the sub options of the freeform type. Note that the option
# discovery doesn't care about the attribute name used here, so this
# is just to avoid conflicts with potential options from the submodule
_freeformOptions = freeformType.getSubOptions prefix;
};
getSubModules = modules;
substSubModules = m: submoduleWith (attrs // {
modules = m;
});
nestedTypes = lib.optionalAttrs (freeformType != null) {
freeformType = freeformType;
};
functor = defaultFunctor name // {
type = types.submoduleWith;
payload = {
modules = modules;
specialArgs = specialArgs;
shorthandOnlyDefinesConfig = shorthandOnlyDefinesConfig;
};
binOp = lhs: rhs: {
modules = lhs.modules ++ rhs.modules;
specialArgs =
let intersecting = builtins.intersectAttrs lhs.specialArgs rhs.specialArgs;
in if intersecting == {}
then lhs.specialArgs // rhs.specialArgs
else throw "A submoduleWith option is declared multiple times with the same specialArgs \"${toString (attrNames intersecting)}\"";
shorthandOnlyDefinesConfig =
if lhs.shorthandOnlyDefinesConfig == rhs.shorthandOnlyDefinesConfig
then lhs.shorthandOnlyDefinesConfig
else throw "A submoduleWith option is declared multiple times with conflicting shorthandOnlyDefinesConfig values";
};
};
};
# A value from a set of allowed ones.
enum = values:
let
show = v:
if builtins.isString v then ''"${v}"''
else if builtins.isInt v then builtins.toString v
else if builtins.isBool v then boolToString v
else ''<${builtins.typeOf v}>'';
in
mkOptionType rec {
name = "enum";
description =
# Length 0 or 1 enums may occur in a design pattern with type merging
# where an "interface" module declares an empty enum and other modules
# provide implementations, each extending the enum with their own
# identifier.
if values == [] then
"impossible (empty enum)"
else if builtins.length values == 1 then
"value ${show (builtins.head values)} (singular enum)"
else
"one of ${concatMapStringsSep ", " show values}";
check = flip elem values;
merge = mergeEqualOption;
functor = (defaultFunctor name) // { payload = values; binOp = a: b: unique (a ++ b); };
};
# Either value of type `t1` or `t2`.
either = t1: t2: mkOptionType rec {
name = "either";
description = "${t1.description} or ${t2.description}";
check = x: t1.check x || t2.check x;
merge = loc: defs:
let
defList = map (d: d.value) defs;
in
if all (x: t1.check x) defList
then t1.merge loc defs
else if all (x: t2.check x) defList
then t2.merge loc defs
else mergeOneOption loc defs;
typeMerge = f':
let mt1 = t1.typeMerge (elemAt f'.wrapped 0).functor;
mt2 = t2.typeMerge (elemAt f'.wrapped 1).functor;
in
if (name == f'.name) && (mt1 != null) && (mt2 != null)
then functor.type mt1 mt2
else null;
functor = (defaultFunctor name) // { wrapped = [ t1 t2 ]; };
nestedTypes.left = t1;
nestedTypes.right = t2;
};
# Any of the types in the given list
oneOf = ts:
let
head' = if ts == [] then throw "types.oneOf needs to get at least one type in its argument" else head ts;
tail' = tail ts;
in foldl' either head' tail';
# Either value of type `coercedType` or `finalType`, the former is
# converted to `finalType` using `coerceFunc`.
coercedTo = coercedType: coerceFunc: finalType:
assert lib.assertMsg (coercedType.getSubModules == null)
"coercedTo: coercedType must not have submodules (its a ${
coercedType.description})";
mkOptionType rec {
name = "coercedTo";
description = "${finalType.description} or ${coercedType.description} convertible to it";
check = x: (coercedType.check x && finalType.check (coerceFunc x)) || finalType.check x;
merge = loc: defs:
let
coerceVal = val:
if coercedType.check val then coerceFunc val
else val;
in finalType.merge loc (map (def: def // { value = coerceVal def.value; }) defs);
emptyValue = finalType.emptyValue;
getSubOptions = finalType.getSubOptions;
getSubModules = finalType.getSubModules;
substSubModules = m: coercedTo coercedType coerceFunc (finalType.substSubModules m);
typeMerge = t1: t2: null;
functor = (defaultFunctor name) // { wrapped = finalType; };
nestedTypes.coercedType = coercedType;
nestedTypes.finalType = finalType;
};
# Obsolete alternative to configOf. It takes its option
# declarations from the options attribute of containing option
# declaration.
optionSet = mkOptionType {
name = "optionSet";
description = "option set";
deprecationMessage = "Use `types.submodule' instead";
};
# Augment the given type with an additional type check function.
addCheck = elemType: check: elemType // { check = x: elemType.check x && check x; };
};
};
in outer_types // outer_types.types