Ok, this is may be a niche library since not many people works with ldap .
For those who do, the de-facto client for ldap is :eldap which is included in otp, but is very low level.
Some elixir libraries exists to abstract it’s interface but no one (afaik) address the standard filtering syntax.
LDAP has a text string filter syntax which is defined in RFC4515, which is commonly used when you want to provide a generic search interface to an ldap server.
This library is a parser for those string and is based on the ABNF grammar defined in the RFC itself.