-proc symplectic*(p: var Parameters, cd: Coefficients,
-                     uq: proc(p: var Parameters, h: float),
-                     up: proc(p: var Parameters, h: float)) =
+proc symplectic[T](p: var T, cd: Coefficients, uq, up)
   for i in countup(0, cd.len - 1):
     if (i mod 2) == 0: uq(p, cd[i]) else: up(p, cd[i])
   for i in countdown(cd.len - 2, 0):
     if (i mod 2) == 0: uq(p, cd[i]) else: up(p, cd[i])

-proc solve*(args: seq[string], p: var Parameters,
-            uq: proc(p: var Parameters, c: float),
-            up: proc(p: var Parameters, d: float),
-            output: proc(p: Parameters, t: float)) =
+proc solve*[T](args: seq[string], p: var T, uq, up, output: proc(p: var T, _: float))
   let
     order: int64 = parseInt(args[1])
     h: float = parseFloat(args[2])