diff options
Diffstat (limited to 'lib/attrsets.nix')
| -rw-r--r-- | lib/attrsets.nix | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/lib/attrsets.nix b/lib/attrsets.nix index 22ecc808679..84f6cb3658b 100644 --- a/lib/attrsets.nix +++ b/lib/attrsets.nix @@ -23,6 +23,17 @@ rec { then attrByPath (tail attrPath) default e.${attr} else default; + /* Return if an attribute from nested attribute set exists. + For instance ["x" "y"] applied to some set e returns true, if e.x.y exists. False + is returned otherwise. */ + hasAttrByPath = attrPath: e: + let attr = head attrPath; + in + if attrPath == [] then true + else if e ? ${attr} + then hasAttrByPath (tail attrPath) e.${attr} + else false; + /* Return nested attribute set in which an attribute is set. For instance ["x" "y"] applied with some value v returns `x.y = v;' */ |