Parentheses in Scheme
Every parenthesis in an S-expression has significance.
(a b c) is different from (a (b c)) or ((a b) c).
To call a zero-argument function, put its name in parentheses: (read) But not ((read))
The empty list is denoted ( ).
Parentheses should always be balanced.
is an incomplete S-expression.
Misplaced paren’s are a leading cause of beginners’ Scheme programming errors.