nixpkgs/pkgs/lib/types.nix
Eelco Dolstra e4ce304333 types.nix: Add a ‘lines’ type
This is like types.string, but values are merged by putting a newline
in between them.  This is mostly useful for configuration file
options, where we don't want values accidentally ending up on the same
line.

Note that almost all options with string type in NixOS should either
be unmergable (i.e. should be marked with ‘types.uniq’) or should
actually be of type ‘lines’.  So it might make sense to remove the
merge function for the ‘string’ type eventually.
2013-02-11 15:32:24 +01:00

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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;
};
};
}