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Order of evaluation when constructing record values
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Date: -- (:)
From: Jeff Meister <nanaki@g...>
Subject: Re: Order of evaluation when constructing record values
I seem to have answered my own question by playing around. It appears
that the order of evaluation is last-to-first and based on the order
of the fields in the type declaration, not in the value construction.
Oh well. I guess it's let-bindings for me.

On 8/11/07, Jeff Meister <nanaki@gmail.com> wrote:
> I ask for forgiveness in advance for this silly pedantic question.
>
> I think my question is best illustrated with an example. Say I have
> this simple record type for holding a date:
>
> type date = { year : int; month : int; day : int; }
>
> Now, I want to read the year/month/day values from stdin, and I know
> they will appear in that order. So I do the following:
>
> let today = {
>   year = read_int ();
>   month = read_int ();
>   day = read_int ();
> }
>
> For this to work, I need the ints to be read in the order given, or I
> could end up with a day of 2007 and a year of 11. Is there any
> guarantee that OCaml will follow that order of evaluation when
> constructing the record? Or do I have to force it with let-bindings
> like this:
>
> let today =
>   let y = read_int () in
>   let m = read_int () in
>   let d = read_int () in
>   { year = y; month = m; day = d; }
>
> Of course, it's not that big a deal for me to just use the let-binding
> method, but I'm curious, and it might make my code look nicer if I can
> rely on order of evaluation.
>