To enter interactive mode, run bin/scam:
% bin/scam
SCAM v2.0 interactive mode. Type '?' for help.
>
The > prompt indicates that it is waiting to accept a SCAM expression.
Let's define a function.
> (define (hello ?name)
+ (print "Hello " (or name "world") "!"))
The + prompt indicates that more input is required to complete the SCAM
expression. The print function is a SCAM builtin that outputs its
arguments to stdout. The ? before name indicates that it is an optional
argument. Now that we have defined a function, let's call it.
> (hello)
Hello world!
> (hello "from SCAM")
Hello from SCAM!
Having only one data type does not limit the language as you might at first imagine. In SCAM we can represent complex data types -- vectors, associative arrays, and first-class functions -- as strings. For example:
> (for f [- + * ^]
+ (f 3 2))
[1 5 6 9]
If you type an expression that returns a value (other than the empty string) REPL displays the returned value, formatting it as valid SCAM source in the simplest form:
> 12
12
> "1 2"
"1 2"
> (cons "a b" [2 3])
["a b" 2 3]
The global variable *1 holds the most recent return value, and *2 holds
the previous return value.
> 7
7
> 9
9
> (* *1 *2)
63