# Module Pprintast.Doc

    module Doc: sig .. end

`Format_doc` functions for error messages

    val longident : Longident.t Format_doc.printer

    val constr : Longident.t Format_doc.printer

    val tyvar : string Format_doc.printer

    val nominal_exp : Parsetree.expression -> Format_doc.t option

Returns a format document if the expression reads nicely as the subject of a sentence in a error message.