Binary package “elpa-sml-mode” in ubuntu oracular

Emacs major mode for editing Standard ML programs

 SML-mode provides syntax highlighting and automatic
 indentation for Standard ML and comes with sml-proc which allows
 interaction with an inferior SML interactive loop. You will need
 this if you write Standard ML programs using Emacs. For OCaml
 prgramming, see instead tuareg-mode.