similar to: RFC: (in-principle) native unquoting for standard evaluation

Would this return a quosure? (i.e. a single sided formula that captures both expression and environment). That's the data structure we've adopted in tidyeval as it already has some built in support. Hadley On Friday, March 17, 2017, Michael Lawrence <lawrence.michael at gene.com> wrote: > Interesting idea. Lazy and non-standard evaluation is going to happen; the > language

On Mon, Mar 20, 2017 at 7:36 AM, Radford Neal <radford at cs.toronto.edu> wrote: > Michael Lawrence (as last in long series of posters)... > >> Yes, it would bind the language object to the environment, like an >> R-level promise (but "promise" of course refers specifically to just >> _lazy_ evaluation). >> >> For the uqs() thing, expanding calls

(please be gentle, it's my first time) I am interested in discussions (possibly reiterating past threads -- searching didn't turn up much) on the possibility of supporting standard evaluation unquoting at the language level. This has been brought up in a recent similar thread here [1] and on Twitter [2] where I proposed the following desired (in-principle) syntax f <-

I love the pointer analogy. Presumably the additional complication of scope breaks this however. * itself would have been a nice operator for this were it not prone to ambiguity (`a * *b` vs `a**b`, from which @ does not suffer). Would this extension require that function authors explicitly enable auto-quoting support? I somewhat envisioned functions seeing the resolved unquoted object (within

Yes, it would bind the language object to the environment, like an R-level promise (but "promise" of course refers specifically to just _lazy_ evaluation). For the uqs() thing, expanding calls like that is somewhat orthogonal to NSE. It would be nice in general to be able to write something like mean(x, extra_args...) without resorting to do.call(mean, c(list(x), extra_args)). If we had

Interesting idea. Lazy and non-standard evaluation is going to happen; the language needs a way to contain it. I'll extend the proposal so that prefixing a formal argument with @ in function() marks the argument as auto-quoting, so it arrives as a language object without use of substitute(). Kind of like how '*' in C declares a pointer and dereferences one. subset <- function(x,

>After off list discussions with Jonathan Carrol and with >Michael Lawrence I think it's doable, unambiguous, >and even imo pretty intuitive for an "unquote" operator. For those of us who are not CS/Lisp mavens, what is an "unquote" operator? Can you expression quoting and unquoting in R syntax and show a few examples where is is useful, intuitive, and fits in to

Your example x = 5 exp = parse(text="f(uq(x)) + y +z") # expression: f(uq(x)) +y + z do_unquote(expr) # -> the language object f(5) + y + z could be done with the following wrapper for bquote my_do_unquote <- function(language, envir = parent.frame()) { if (is.expression(language)) { # bquote does not go into expressions, only calls

I agree there is no reason they _need_ to be the same precedence, but I think SPECIALS are already have the proper precedence for both unary and binary calls. Namely higher than all the binary operators (except for `:`), but lower than the other unary operators. Even if we gave unary specials their own precedence I think it would end up in the same place. `%l%` <- function(x) tail(x, n =

The unquoting discussion is IMHO separate from this proposal and as you noted probably better served by a native operator with different precedence. I think the main benefit to providing user defined prefix operators is it allows package authors to experiment with operator ideas and gauge community interest. The current situation means any novel unary semantics either need to co-opt existing

I would like a function to strip quotes off character strings. I should work like this: > A <- matrix(1:6, nrow = 2, ncol=3) > AF <- as.data.frame(A) > names(AF) <- c("First","Second","Third") > AF First Second Third 1 1 3 5 2 2 4 6 > names(AF)[2] [1] "Second" > attach(AF) >

Martin, Jim can speak directly to his motivations; I don't claim to be able to do so. That said, I suspect this is related to a conversation on twitter about wanting an infix "unquote" operator in the context of the non-standard evaluation framework Hadley Wickham and Lionel Henry (and possibly others) are working on. They're currently using !!! and !! for things related to

I guess this would establish a separate "namespace" of symbolic prefix operators, %*% being an example in the infix case. So you could have stuff like %?%, but for non-symbolic (spelled out stuff like %foo%), it's hard to see the advantage vs. foo(x). Those examples you mention should probably be addressed (eventually) in the core language, and it looks like people are already able

Gabe, The unary functions have the same precedence as normal SPECIALS (although the new unary forms take precedence over binary SPECIALS). So they are lower precedence than unary + and -. Yes, both of your examples are valid with this patch, here are the results and quoted forms to see the precedence. `%chr%` <- function(x) as.character(x) `%identical%` <- function(x, y)

William, Unbeknownst to me when I sent this, Jonathon Carrol started a specific thread about unquoting and a proposal for supporting it at the language level, which I think is a better place to discuss unquoting specifically. That said, the basics as I understand them in the context of non-standard evaluation, unquoting (or perhaps interpolation) is essentially substituting part of an unevaluated

Bill, Right. My example was the functional form for clarity. There is a desire for a unary-operator form. (rlang's !! and !!! operators described in the comments in the file I linked to). I can't really make that argument because I'm not one of the people who wanted that. You'd have to talk to the authors of the rlang package to find out their reasons for thinking that is

On Wednesday, 4 October 2017 14:56:23 CEST Richard W.M. Jones wrote: > If you have a struct containing ‘field’, eg: > > type t = { field : int } > > then previously to pattern-match on this type, eg. in function > parameters, you had to write: > > let f { field = field } = > (* ... use field ... *) > > In OCaml >= 3.12 it is possible to abbreviate

Changes from v2 to v3: - split_key_value_strings renamed to parse_key_value_strings Changes from v1 to v2: - split the "simple unquoting" as helper - pass the unquoting function to split_key_value_strings - use right unquoting function when applying split_key_value_strings Pino Toscano (2): daemon: add split_key_value_strings helper daemon: use parse_key_value_strings

Dear R-devel, There is a new feature in R-devel, which explicitly refers to LISP @ operator for splicing. > The backquote function bquote() has a new argument splice to enable splicing a computed list of values into an expression, like ,@ in LISP's backquote. Although the most upvoted SO question asking for exactly LISP's @ functionality in R doesn't seems to be addressed by this

Changes from v1 to v2: - split the "simple unquoting" as helper - pass the unquoting function to split_key_value_strings - use right unquoting function when applying split_key_value_strings Pino Toscano (2): daemon: add split_key_value_strings helper daemon: use split_key_value_strings daemon/inspect_fs_unix.ml | 93 +++++++++++++++++++---------------------------- daemon/md.ml