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# Definitions related to run-time type checking. Used in particular
# to type-check NixOS configurations.
let lib = import ./default.nix; in
with import ./lists.nix;
with import ./attrsets.nix;
with import ./options.nix;
with import ./trivial.nix;
rec {
hasType = x: isAttrs x && x ? _type;
typeOf = x: x._type or "";
setType = typeName: value: value // {
_type = typeName;
};
# name (name of the type)
# check (boolean function)
# 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 = attrs: typeOf attrs == "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)
, 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;
};
types = rec {
inferred = mkOptionType {
name = "inferred type";
};
bool = mkOptionType {
name = "boolean";
check = lib.traceValIfNot builtins.isBool;
merge = fold lib.or false;
};
int = mkOptionType {
name = "integer";
check = lib.traceValIfNot builtins.isInt;
};
string = mkOptionType {
name = "string";
check = lib.traceValIfNot builtins.isString;
merge = lib.concatStrings;
};
# Like ‘string’, but add newlines between every value. Useful for
# configuration file contents.
lines = mkOptionType {
name = "string";
check = lib.traceValIfNot builtins.isString;
merge = lib.concatStringsSep "\n";
};
envVar = mkOptionType {
name = "environment variable";
inherit (string) check;
merge = lib.concatStringsSep ":";
};
attrs = mkOptionType {
name = "attribute set";
check = lib.traceValIfNot isAttrs;
merge = fold lib.mergeAttrs {};
};
# derivation is a reserved keyword.
package = mkOptionType {
name = "derivation";
check = lib.traceValIfNot isDerivation;
};
path = mkOptionType {
name = "path";
# Hacky: there is no ‘isPath’ primop.
check = lib.traceValIfNot (x: builtins.unsafeDiscardStringContext (builtins.substring 0 1 (toString x)) == "/");
};
listOf = types.list;
list = 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;
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 ${elemType.name}s";
check = x: lib.traceValIfNot isAttrs x
&& fold (e: v: v && elemType.check e) true (lib.attrValues x);
merge = lib.zip (name: elemType.merge);
iter = f: path: set: lib.mapAttrs (name: elemType.iter f (path + "." + name)) set;
fold = op: nul: set: fold (e: l: elemType.fold op l e) nul (lib.attrValues set);
docPath = path: elemType.docPath (path + ".<name>");
inherit (elemType) hasOptions delayOnGlobalEval;
};
# List or attribute set of ...
loaOf = elemType:
let
convertIfList = defIdx: def:
if isList def then
listToAttrs (
flip imap def (elemIdx: elem:
nameValuePair "unnamed-${toString defIdx}.${toString elemIdx}" elem))
else
def;
listOnly = listOf elemType;
attrOnly = attrsOf elemType;
in mkOptionType {
name = "list or attribute set of ${elemType.name}s";
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";
docPath = path: elemType.docPath (path + ".<name?>");
inherit (elemType) hasOptions delayOnGlobalEval;
}
;
uniq = elemType: mkOptionType {
inherit (elemType) name check iter fold docPath hasOptions;
merge = list:
if length list == 1 then
head list
else
throw "Multiple definitions. Only one is allowed for this option.";
};
none = elemType: mkOptionType {
inherit (elemType) name check iter fold docPath hasOptions;
merge = list:
throw "No definitions are allowed for this option.";
};
nullOr = elemType: mkOptionType {
inherit (elemType) name merge docPath hasOptions;
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;
};
functionTo = elemType: mkOptionType {
name = "function that evaluates to a(n) ${elemType.name}";
check = lib.traceValIfNot 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;
};
# !!! this should be a type constructor that takes the options as
# an argument.
optionSet = mkOptionType {
name = "option set";
# merge is done in "options.nix > addOptionMakeUp > handleOptionSets"
merge = lib.id;
check = x: isAttrs x || builtins.isFunction x;
hasOptions = true;
delayOnGlobalEval = true;
};
};
}
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