[Ur] signal monad semantics

[Gergely Buday]

Hi there,

the manual says

"By
 using signal on a source, you implicitly subscribe to change
notications for that source. That is, your signal
 will automatically be recomputed as that source changes"

My question is: does this simply mean that upon "set"-ting a source
triggers the signal monad to fire, or a comparison is done whether the
new value is different from the previous?

- Gergely