lib.optionalDrvAttr

Conditionally set a derivation attribute.

Because mkDerivation sets __ignoreNulls = true, a derivation attribute set to null will not impact the derivation output hash. Thus, this function passes through its value argument if the cond is true, but returns null if not.

Inputs

cond

Condition

value

Attribute value

Type

optionalDrvAttr :: Bool -> a -> a | Null

Examples

(stdenv.mkDerivation {
  name = "foo";
  x = optionalDrvAttr true 1;
  y = optionalDrvAttr false 1;
}).drvPath == (stdenv.mkDerivation {
  name = "foo";
  x = 1;
}).drvPath
=> true

Noogle detected

• lib.derivations.optionalDrvAttr

optionalDrvAttr = cond: value: if cond then value else null;