Version française
Home     About     Download     Resources     Contact us    
Browse thread
[Caml-list] why the "rec" in "let rec"?
[ Home ] [ Index: by date | by threads ]
[ Search: ]

[ Message by date: previous | next ] [ Message in thread: previous | next ] [ Thread: previous | next ]
Date: -- (:)
From: Neel Krishnaswami <neelk@a...>
Subject: Re: [Caml-list] why the "rec" in "let rec"?
Hal Daume III writes:
> 
> Both responses so far have pointed out how it's different from jsut 'let',
> but I don't think this was the point of the question.  Arguably, the
> "simplest" way to dealing with:
> 
> > let f x = ..
> > let f x = f x
> 
> is to simply disallow bindings like this.  I would think that
> they're almost always a bug.  Especially if the first definition
> appears at the top of your file and the second (perhaps you forgot
> the "rec" and the body is actually long) appears at the bottom.
> Likely it would turn out to be a type error anyway, but why risk it?
> 
> Anyway, I think the question was more along the lines of "why let
> the programmer do something like this."  I cannot answer that.

Unless I misremember, Java has lexical scope, but forbids bindings
from shadowing one another. I don't know what relevance this has,
except to note that your idea has actually been implemented in a real
language. I don't think one can say whether this is helpful or not,
because the rest of Java is so much less expressive than Ocaml....

-- 
Neel Krishnaswami
neelk@alum.mit.edu

-------------------
To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr
Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/
Beginner's list: http://groups.yahoo.com/group/ocaml_beginners