Here is a short tip if someone would like to install SML Compiler on Ubuntu.

Standard ML of New Jersey interactive compiler
SML/NJ is an implementation of the Standard ML programming language.
Standard ML has many features, including type safety, polymorphism,
algebraic data types with pattern matching, higher-order functions,
and a sophisticated module system. It is especially well-suited for
writing compilers and other language processors.

This package includes the interactive compiler (sml), the compilation
manager (CM), and some essential libraries. It is a “working”
version, but believed to be stable.

Install this package if you want to program in SML.

Type in command line:

The sml will be installed under /usr/bin/sml