# CSE 505 -- Very Rough Notes on Higher Order Functions in Pizza

November 1999
Higher-order functions supported in Pizza
These are available in Algol 60, although not as first-class citizens
used pervasively in languages like Smalltalk, Miranda, Scheme
EXAMPLE:
int n;
(int) -> int f;
(char,int) -> bool g;
() -> int h;
f, g, h are variables that hold functions
f = fun (int k)->int { return k+1};
n = f(5);
also see Radix example in Pizza paper
NON-LOCAL VARIABLES IN THE FUNCTIONS:
class Squid {
public int n = 0;
public (int) -> int inc() {
return fun (int k) -> int {
return n+k;
}
}
}
squid s;
int i,j,k;
(int) -> int f;
s = new Squid();
f = s.inc();
i = f(3);
s.n = 10;
j = f(3);