[Nickle] continuation bug in nickle

[Plutonium 186]

The following code was intended as an example in the Nickle tutorial about 
continuations. It implements a simple binary tree search that longjmp()s out 
when the match is found; however, although longjmp() seems to be jumping 
somewhere (as evidenced by the debug statements), it does not jump to the 
setjmp() (as evidenced by the other debug statements). This seems like a 
bug.

-----
typedef tree;

typedef struct {
        int key;
        poly data;
        &poly left, right;
} tree;

void function search ( tree t, int i, &continuation c ) {
        if ( i < t.key && ! is_void ( t.left ) )
                search ( t.left, i, &c );
        else if ( i > t.key && ! is_void ( t.right ) )
                search ( t.right, i, &c );
        else if ( i == t.key ) {
                printf ( "key found\n" );
                longjmp ( c, t.data );
                assert(false, "longjmp failed\n" );
        }
}

tree t = { key = 2, data = "blah", left = reference ( <> ), right = 
reference ( <> ) };

continuation c;
int i = 0;
poly p = setjmp ( &c, <> );
++i;
printf ( "I have been here %d times.\n", i );

if ( is_void ( p ) )
        search ( t, 2, &c );
else
        printf ( "value = %g\n", p );
-----

Robert Burgess

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