Single-line comments start with a semicolon:
; This is a comment Multi-line comments are in between #| and |#
#| This is
a
multi-line
comment |#Usually, when we write mathematical expressions, we use infix syntax.
For example, we might write 3 + 2, where the operator is between the numbers. This is just a human convention; we could also use postfix syntax such as writing 3 2 +
However, Racket uses a prefix syntax. The operator comes at the beginning in expressions.
To find 3 + 2, you would write (+ 3 2) in Racket.
By using parenthesis, nesting becomes possible. If we wanted to find 3 + 5 * 2,
for example, we could write (+ 3 (* 5 2)).
The (* 5 2) would evaluate to 10, and the expression would become (+ 3 10)
which evaluates to 13.
We introduced some basic arithmetic functions already like + and *. Booleans (true or false values) and Strings (text) also can have functions applied to them.
Booleans are written as #t for true and #f for false.
Some functions on booleans:
(not #t) => #f (or #t #f) => #t (and #t #f) => #fStrings are blocks of text.
You can print them using using the printf function
(printf "Hello Racket") => "Hello Racket"Variables allow you to assign a value to something which can be used again in your code.
You create a variable using the define keyword:
(define x 3) ; assigns the number 3 to x(* x 2) => 6Functions take in an input and use them to produce an output.
You can create functions using the define keyword with the list of parameters going in parenthesis.
Example:
(define (greeting name)
(string-append "Greetings, " name))(greeting "Bob") => "Greetings, Bob"