Notes on using SML

Grading of programming assingments will be done on the Andrew UNIX machines, so you should test your programs on these machines. You can remotely connect:
- Under Linux or Mac OS X, open a terminal and use ssh to connect to unix.andrew.cmu.edu.
- Under Windows, use PuTTY (or some other SSH client).

If you store your homework files in your personal AFS folder, make sure that your AFS permissions are set so that other students cannot read your files! Example:

    [wklieber@unix35 ~/15212]$ fs setacl . `whoami` all -clear
    [wklieber@unix35 ~/15212]$ fs listacl .
    Access list for . is
    Normal rights:
      wklieber rlidwka

You can also install SML directly on your personal computer. Version 110.69 is the version currently being used on the Andrew machines (as of August 2010).
Interactive mode:
- To start the SML interpreter at the terminal, type "sml" and press enter. If the left/right cursor keys don't work, run "rlwrap sml" instead. Using rlwrap also provides a history; use the up/down arrows to access previously entered lines.
- To exit SML, press CTRL+D (or CTRL+Z under Windows).
- Press CTRL+C to interrupt SML or start a new input line.
- As an example, type "2 + 2;" at the SML prompt and press enter. (Don't forget the semicolon.) Your terminal should look like the following:
```
    [wklieber@unix35 ~]$ rlwrap sml
    Standard ML of New Jersey v110.69 [built: Wed Apr 29 12:25:34 2009]
    - 2 + 2;
    val it = 4 : int
```
  The SML interpreter automatically introduces a new variable named "it" that contains the value of the last evaluated input line. "val it = 4 : int" means that the value of the variable it is 4 and its type is int.
A few syntactic differences from C-like languages:
- Function application: In SML, each function can be thought of as taking exactly one argument, although that argument can be a tuple. Writing "foo(2, 3)" in SML means to apply the function foo to the tuple (2, 3).
```
    - fun foo (x, y) = x+y;
    val foo = fn : int * int -> int
    - foo (2, 3);
    val it = 5 : int
    - val bar = (2, 3);
    val bar = (2,3) : int * int
    - foo bar;
    val it = 5 : int 
```
- Arithmetic:
  - Negation is performed by prefix "~" instead of prefix "-".
  - Integer division is performed by infix "div" (e.g., "5 div 2").
  - Inequality test is "<>" instead of "!=".
  - SML doesn't automatically convert between floats and ints. Writing "2 + 3.0" yields an error in SML. Use the function real to convert an int to a float, and use round, ceil, or floor to convert a float to an int.
- Boolean logic: Use "andalso" and "orelse"; "and" does something else (to be explained later).
- Strings: Caret ("^") concatenates two strings.
- Comments: (* This is a comment *) instead of /* This is a comment */.
Control.Print.printDepth := 100; Control.Print.printLength := 100;