Since `hash-ref!` includes `or`-like functionality, is there a reason it's not implemented with short-circuit logic similar to `or`?
In other words, the function `hash-ref!` is invoked thus: (hash-ref! hashtable key new-value-if-needed) What I notice is that if you put an expression in the new-value position, like so: (hash-ref! hashtable key (expression-that-produces-value)) Then this expression will always be evaluated before the function is called. But this seems wasteful, since if 'key' exists in 'hashtable', the expression won't be needed. `hash-ref!` will also take a thunk, so you can manually delay evaluation of the value expression by wrapping it in λ: (hash-ref! hashtable key (λ () (expression-that-produces-value))) But I'm curious why delayed evaluation isn't the default behavior. ____________________ Racket Users list: http://lists.racket-lang.org/users
