It sounds from the later posts like you've made some progress. I just want to call out one thing: Quoting Damien Mattei (2018-12-05 11:02:48)
let name = "'A 20'" let qry = "select `N° BD` from Coordonnées where Nom = " ++ name
I'll hazard a guess that you're using the sqlite-simple library. From their documentation on the Query type:
This type is intended to make it difficult to construct a SQL query by concatenating string fragments, as that is an extremely common way to accidentally introduce SQL injection vulnerabilities into an application.
From later messages it looks like you worked out the OverloadedStrings thing and ended up (correctly) moving to some code that uses the ? interpolation syntax: ".... where Nom = ?". I just wanted to stress that this is the right way to do things, and the distinction is important. This is a general thing when working with SQL: don't construct queries by gluing strings together; it's a great way to have vulnerabilities in your app. Happy Hacking, -Ian