[Ur] Need help with desugaring dml

[Sergey Mironov]

Hi. I'm trying (again) to write an Ur/Web module to provide API for
managing OS-level processes. I expect users to pass it a table
containing _at_least_ id, process command name, arguments, placeholder
for exit code and status string. It is expected that users will use
tables containing more problem-specific columns.

The problem is that I cant use simple dml operations anymore. As a
start, I tried to write dummy insert using [demo/more/orm.ur] as
example, but was stopped by difficult [ensql] function. Could you
please help me to implement it?  The code is quite short and listed
below.

Regards,
Sergey

---

con jobinfo = [
    Id = int
  , ExitCode = option int
  , Cmd = string
  , Hint = string
  ]

functor Make(M : sig

  con u

  constraint [Id,ExitCode,Cmd,Hint] ~ u

  table t : (jobinfo ++ u)

  sequence s

end) = struct

  open CallbackFFI

  type row' = record (jobinfo ++ M.u)

  (* fun ensql [avail ::_] (r : row') : $(map (sql_exp avail [] []) fs') = *)
  (*     @map2 [meta] [fst] [fn ts :: (Type * Type) => sql_exp avail
[] [] ts.1] *)
  (*      (fn [ts] meta v => @sql_inject meta.Inj v) *)
  (*      M.folder M.cols r *)

  (* createSync will start the job, but in this example it just does a
simple insert.
    args is a problem-specific part of the table record.

    How to make this dml(insert..) work? *)

  fun createSync (ji : record jobinfo, args : record M.u) :
transaction (option int) =
    i <- nextval M.s;
    dml(insert M.t ({Id = sql_inject ji.Id,
          ExitCode = sql_inject ji.ExitCode,
          Cmd = sql_inject ji.Cmd,
          Hint = sql_inject ji.Hint} ++ (ensql args) ));

    return (Some i)

end