Sequencing

(begin {expression1} {expression2} ... ) syntax
This form of begin can be used as an ordinary expression. The expressions are evaluated sequentially from left to right, and the values of the last expression are returned. This expression type is used to sequence side effects such as assignments or input and output.
(define x 0) (and (= x 0) (begin (set! x 5) (+ x 1))) ==> 6 (begin (display "4 plus 1 equals ") (display (+ 4 1))) ==> unspecified and prints 4 plus 1 equals 5

Note that there is another form of begin used as a library declaration: see section 5.6.1.

husk-scheme online documentation rev 3.19.3 (2016.07.10)