Problem in 3.5.1

[clean99]

I think here the stream_filter will return

pair(head(stream), 
     () => stream_filter(pred, stream_tail(stream)));

instead of

pair(head(stream), 
     stream_filter(pred, stream_tail(stream)));

If it calls stream_filter directly in the tail, it will become an ordinary list?

[martin-henz]

Yes, you are right! Thanks for this keen observation! Will fix this in the next printing, and in the online edition.