Termination problem on tree-transformation program

Question

Termination problem on tree-transformation program

gsvgit opened this issue 3 years ago · comments

Hello.

I try to use Distiller for tree-manipulation programs transformation, but I have the following problem.

Suppose I have the following function:

eWizeOp g s m = 
    case m of
           Val (v1) -> (Val (g v1 s))
         | Node (q1, q2) -> (Node ((eWizeOp g s q1), (eWizeOp g s q2)))

When I try to distill the following term

main =  eWizeOp g s2 (eWizeOp g2 s m) ;

the result is correct, but when I try to distill the term

main =  eWizeOp g s2 (eWizeOp g s m) ;

the distiller does not terminate.

The only difference between these two cases is that I use the same first parameter in both calls of the eWizeOp function in the second case.

Full tests.

-- OK
main =  eWizeOp g s2 (eWizeOp g2 s m) ;

eWizeOp g s m = 
    case m of
           Val (v1) -> (Val (g v1 s))
         | Node (q1, q2) -> (Node ((eWizeOp g s q1), (eWizeOp g s q2)))

-- Fail
main =  eWizeOp g s2 (eWizeOp g s m) ;

eWizeOp g s m = 
    case m of
           Val (v1) -> (Val (g v1 s))
         | Node (q1, q2) -> (Node ((eWizeOp g s q1), (eWizeOp g s q2)))

Geoff Hamilton · Answer 1 · Tue Jun 15 2021 00:00:59 GMT+0800 (China Standard Time)

Hi, Thanks for this - I will take a look at it and get back to you. Best regards, Geoff.

…

On Mon, 14 Jun 2021 at 16:54, Semyon ***@***.***> wrote: Hello. I try to use Distiller for tree-manipulation programs transformation, but I have the following problem. Suppose I have the following function: eWizeOp g s m = case m of Val (v1) -> (Val (g v1 s)) | Node (q1, q2) -> (Node ((eWizeOp g s q1), (eWizeOp g s q2))) When I try to distill the following term main = eWizeOp g s2 (eWizeOp g2 s m) ; the result is correct, but when I try to distill the term main = eWizeOp g s2 (eWizeOp g s m) ; the distiller does not terminate. The only difference between these two cases is that I use the same first parameter in both calls of the eWizeOp function in the second case. Full tests. -- OK main = eWizeOp g s2 (eWizeOp g2 s m) ; eWizeOp g s m = case m of Val (v1) -> (Val (g v1 s)) | Node (q1, q2) -> (Node ((eWizeOp g s q1), (eWizeOp g s q2))) -- Fail main = eWizeOp g s2 (eWizeOp g s m) ; eWizeOp g s m = case m of Val (v1) -> (Val (g v1 s)) | Node (q1, q2) -> (Node ((eWizeOp g s q1), (eWizeOp g s q2))) — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#1>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAEFW7SAWDYDCR4HKX2TYGDTSYQ2VANCNFSM46VQI2WQ> .

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Geoff Hamilton · Answer 2 · Tue Jun 15 2021 03:57:53 GMT+0800 (China Standard Time)

This is now fixed. There are other minor issues I am currently working on - a major update is due soon,

Semyon · Answer 3 · Tue Jun 15 2021 11:24:27 GMT+0800 (China Standard Time)

Thank you very much! Looking forward to an updated version!