I'm using Mac OSX 10.7.5 and I can't seem to get download a working Standard ML compiler with a REPL available. Is this supposed to be so difficult? Is there a best ML that I should be downloading. I've tried SML/NJ and MLton to no avail.
A Mac user can also use
$ brew install smlnj
Add path similar to /usr/local/Cellar/smlnj/110.82/libexec/bin
to your .bash_profile.
$ source ~/.bash_profile
See this article for more information.