Node:begin, Next:if cond case, Up:Control Mechanisms
begin is used for grouping several expression together so that
they syntactically are treated as if they were one expression. This is
particularly important when syntactic expressions are used which only
allow one expression, but the programmer wants to use more than one
expression in that place. As an example, consider the conditional
expression below:
(if (> x 0)
(begin (display "greater") (newline)))
If the two calls to display and newline were not embedded
in a begin-statement, the call to newline would get
misinterpreted as the else-branch of the if-expression.
| begin expr1 expr2 ... | syntax |
The expression(s) are evaluated in left-to-right order and the value
of the last expression is returned as the value of the
begin-expression. This expression type is used when the
expressions before the last one are evaluated for their side effects.
|