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From: Brian Hurt <bhurt@spnz.org>
To: Dustin Sallings <dustin@spy.net>
Cc: Caml Mailing List <caml-list@inria.fr>
Subject: Re: [Caml-list] tail call optimization
Date: Wed, 19 Nov 2003 11:22:40 -0600 (CST)	[thread overview]
Message-ID: <Pine.LNX.4.44.0311191114240.5009-100000@localhost.localdomain> (raw)
In-Reply-To: <FE0B59A6-1A58-11D8-A557-000393CB0F1E@spy.net>

On Tue, 18 Nov 2003, Dustin Sallings wrote:

> 
> On Nov 18, 2003, at 22:50, Brian Hurt wrote:
> 
> > This function is not tail recursive.  Basically, if the recursive call
> > either a) is wrapped in a try block, or b) has it's return value 
> > modified
> 
> 	I guess I don't understand the point of clause a.  The try block 
> doesn't seem like it should prevent the optimization.

What would happen if f just happened to throw an End_of_file exception?  
Not to mention the fact that it's tricky for the compiler to determine 
that the call to fold_lines can't throw an End_of_file.  So the compiler 
just assumes that both might, and thus has to keep the try/catch block, 
and the context (stack frame) of the function, alive until both are 
complete.

-- 
"Usenet is like a herd of performing elephants with diarrhea -- massive,
difficult to redirect, awe-inspiring, entertaining, and a source of
mind-boggling amounts of excrement when you least expect it."
                                - Gene Spafford 
Brian


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  parent reply	other threads:[~2003-11-19 16:24 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-11-19  5:24 Dustin Sallings
     [not found] ` <3FBB0247.2000401@cs.caltech.edu>
2003-11-19  6:07   ` Dustin Sallings
2003-11-19  6:50 ` Brian Hurt
2003-11-19  6:24   ` Dustin Sallings
2003-11-19 11:40     ` Frederic van der Plancke
2003-11-19 17:22     ` Brian Hurt [this message]
2003-11-19 17:45       ` Dustin Sallings

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