In the definition of the term "direct superclass", it:

says: The class from which a class or trait it is immediately derived

should say: The class from which a class or trait is immediately derived

FIXED in 2ed

The index entry for () i.e. open / close parentheses should cross refer
to the apply function, and page 39, at least.

DONE in 2ed

There is no reference under @ in the index (page 712 paper, 730 pdf) to
the use of @ as a variable assignment in pattern matches, as introduced
on page 277 (307 pdf).

This is unfortunate as it is quite difficult to search electronically for
references to symbols using engines optimised for words.

FIXED in 2ed

Typo:
  lamda -> lambda

FIXED in 2ed