Numbers

Exact integers and fractions

Kawa has the usual syntax for decimal integers. Addition, subtraction, and mutliplication are written using the usual +, -, and *, but these are all prefix functions that take a variable number of arguments:

(+ 1 2 3) ⇒ 6
(- 10 3 4) ⇒ (- (- 10 3) 4)  ⇒ 3
(* 2 -6)  ⇒ -12

Kawa has arbitrary-precision integers.

Let us implement the factorial function. Type in the following (we'll look at the syntax shortly):

#|kawa:1|# (define (factorial x)
#|(---:2|#   (if (< x 1) 1
#|(---:3|#     (* x (factorial (- x 1)))))

(The prompt changes to indicate a continuation line.) This binds the name factorial to new function, with formal parameter x. This new function is immediately compiled to Java bytecodes, and later a JIT compiler may compile it to native code.

A few tests:

#|kawa:4|# (list (factorial 3) (factorial 4))
(6 24)
#|kawa:5|# (factorial 30)
265252859812191058636308480000000

Floating-point real numbers

Complex numbers

Units and dimensions