common sub-expressions

[damieiro]

 
It could be funny having a poll of free pascal forum ages...

When did you born?
50-60s
60-70s
70s-80->i' m here more near than 70s

And so on..

[Paolo]

ehm.. let me say just before '70s

[Paolo]

@markov,

Are there examples of symbolic unit usage ?

[J-G]

It could be funny having a poll of free pascal forum ages...

When did you born?
50-60s
60-70s
70s-80->i' m here more near than 70s

And so on..

You started too late   ----  40's !!   

[BobDog]

You are going the wrong way chronologically, you must go back deeper into the mists of time to catch me!

[PascalDragon]

Everyone, please, back to topic. This is not about ones age, but about sub expressions.

[MarkMLl]

Seconded, FWIW. However I'd suggest that peoples' background /can/ be important in this area: as an engineer (and one who predates most CS departments) I'm inclined to be dismissive of stuff that sounds like CS geekery: but in this case the concept of an Abstract Syntax Tree that can be manipulated systematically is deeply important.

One thing I would say though is that it might turn out to be necessary to store the original source text at each node for debugging/listing purposes, but this can obviously be difficult to manipulate. So one might perforce end up with both storage for a source fragment, plus a way of regenerating something that approximates source from a node where e.g. two leaves have been exchanged to bring it in line with others which might at a later stage be elided as common subexpressions.

MarkMLl

[marcov]

@markov,

Are there examples of symbolic unit usage ?

there are some in packages\symbolic\examples, but they are quite basic.