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hasAttrByPath

lib.attrsets.hasAttrByPath

Docs pulled from | This Revision | 31 minutes ago


Return if an attribute from nested attribute set exists.

Nix has a has attribute operator ?, which is sufficient for such queries, as long as the number of attributes is static. For example:

(x?a.b) == hasAttrByPath ["a" "b"] x
# and
(x?${f p}."example.com") == hasAttrByPath [ (f p) "example.com" ] x

Laws:

  1. hasAttrByPath [] x == true
    

Inputs

attrPath

A list of strings representing the attribute path to check from set

e

The nested attribute set to check

Type

hasAttrByPath :: [String] -> AttrSet -> Bool

Examples

lib.attrsets.hasAttrByPath usage example

x = { a = { b = 3; }; }
hasAttrByPath ["a" "b"] x
=> true
hasAttrByPath ["z" "z"] x
=> false
hasAttrByPath [] (throw "no need")
=> true

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Aliases