import std/tables
type
  Foo = object
  Bar = distinct Table[string, Foo]

proc `[]`(bar: Bar, key: string): Foo = Table[string, Foo](bar)[key]
proc initTable(values: seq[tuple[key: string, value: Foo]]): Bar =
  var table = initTable[string, Foo]()

  for value in values:
    table[value.key] = value.value

  result = table.Bar

var b = initTable(@[("la", Foo()), ("le", Foo()), ("li", Foo())])
# Bam, read only, no manipulation possible unless you cast back explicitly from
# the distinct