Tips on Using SML on Attu

• A common way to use sml is to use two windows, one for editing and one for running the sml interpreter. The two most popular unix editors are emacs and vi. You might want to consider pico if you want an editor that is easy to learn.

• If you're going to use emacs, you'll want to have it go into "sml mode" for files ending in ".sml". You do this by creating a file called ".emacs" (including the dot in the name) in your home directory. Take a look at Stuart's .emacs file for an example (you can save this in your home directory if you want).

• There is a utility program called rlwrap that is available on attu. Using rlwrap, you'll get a history capability where you can use the arrow keys to go back to previous expressions that you have entered. It also provides better "in line" editing if you know emacs-style commands (e.g., ctrl-e to go to the end of the line, ctrl-a to go to the beginning of the line). To use the program, you would start up sml with this command:

            rlwrap sml
  

  It is convenient to define this as an alias. You should have a file on your attu account called ".bashrc" (the dot is part of the file name). When you edit this file, you'll see a comment towards the end that indicates that you can include your own aliases. Add this line:

            alias sml="rlwrap sml"
  

  Then log out and log back in and you should find that you can say simply "sml" to get the same behavior.

• You will find that sml doesn't print longer answers. For example, if a list is long, it will print just the beginning part of the list and then will use an ellipsis ("...") to indicate that there is more info that it is not showing. You can override this by setting various environment variables. The most important is "print.length". For example, you can modify your alias to say:

            alias sml="rlwrap sml -Cprint.length=1000"
  

  Notice that the setting goes at the end of the alias.

• Another environment variable you might want to set is print.depth, which determines how deeply ML will display nested structures like trees. It is set in a similar manner, so you might modify your alias to:

            alias sml="rlwrap sml -Cprint.length=1000 -Cprint.depth=20"