# R-alpha: New version of R for testing

**Ross Ihaka
**
ihaka@stat.auckland.ac.nz

*Sun, 27 Jul 1997 16:03:49 +1200 (NZST)*

Peter Dalgaard BSA writes:
> Ross Ihaka <ihaka@stat.auckland.ac.nz> writes:
>
> > NEW FEATURES
> >
> > o "expressions" are now implemented as a basic type rather than as
> > a class of object. This change was made as move toward compatibility
> > with S and also to implement mathematical annotation in graphs.
>
> Something looks wrong:
>
> > expression(2+2)
> expression(2 + 2)
> > expression(2+2)[[1]]
> expression(2 + 2)
> > expression(2+2)[[1]][[1]]
> expression(2 + 2)
>
> - How the blazes is a poor soul supposed to get at the parse tree for
> an expression? According to the docs, an expression is supposed to be
> a list of calls, but obviously
Oops sorry. Incomplete implementation. I have a fix for this now as
will as fixes for mutations of expressions of the form
> e <- expression(x+y)
> e[[1]][[1]] <- as.name("f")
I hope to have patches and an "a2" release later this week.
Ross
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