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implement Fibonacci;
include "sys.m";
include "draw.m";
Fibonacci: module
{
init: fn(nil: ref Draw->Context, argv: list of string);
};
init(nil: ref Draw->Context, nil: list of string)
{
sys := load Sys Sys->PATH;
for(i := 0; ; i++){
f := fibonacci(i);
if(f < 0)
break;
sys->print("F(%d) = %d\n", i, f);
}
}
FIB: exception(int, int);
HELP: con "help";
NOVAL: con -1000000000;
fibonacci(n: int): int
{
{
fib(1, n, 1, 1);
}
exception e{
FIB =>
(x, nil) := e;
return x;
* =>
return NOVAL;
}
return NOVAL;
}
fib(n: int, m: int, x: int, y: int) raises (FIB)
{
if(n >= m)
raise FIB(x, y);
{
fib(n+1, m, x, y);
}
exception e{
FIB =>
(x, y) = e;
x = x+y;
y = x-y;
raise FIB(x, y);
* =>
raise HELP;
}
}
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