  VI.4
Locations
Variables [Slide 185]
Variables [Slide 186]
Variables and expressions may be of any of the following types:
integer: 
0, 42, 97, etc. 
Boolean: 
true, false. 
list: 
Lists may be of ﬁxed or variable length. 
string:  String constants are of the form "abc". 
ﬂoat: 
Float constants are of the form $0.123$ or $0.123e+10$. 
lambda: 
This is the type of predicates and functions. 

The function type(X) returns a string representing the type of
expression X. For example, type(9)="integer".
  