SQL is a relatively popular programming language that lets you deal quite sanely with relational data. Then there's Prolog, Kanren, Mercury… which are admitted

SQL is a relatively popular programming language that lets you deal quite sanely with relational data. Then there's Prolog, Kanren, Mercury… which are admittedly not especially popular. The so-called “impedance mismatch” comes mostly from people who don't understand all that SQL can do and inevitably end up replicating it in some other language.