Warning when calling formals() for `[`.

There is more "fun" afoot here, but I don't recall what the point may be:

args(get("+"))

function (e1, e2)
NULL

args(get("["))

NULL

get("[")

.Primitive("[")

get("+")

function (e1, e2)  .Primitive("+")

The other index operators, "[[", "[<-", "[[<-" are similar

The docs are pretty clear that args() on a primitive should yield a closure, so at least the documentation seems to be wrong.

-pd

On 6 Oct 2018, at 19:26 , Laurent Gautier <lgautier at gmail.com> wrote:

Hi,

A short code example showing the warning might the only thing needed here:

```

formals(args(`[`))

NULL

*Warning message:In formals(fun) : argument is not a function*

is.function(`[`)

[1] TRUE

is.primitive(`[`)

[1] TRUE
```

Now with an other primitive:

```

formals(args(`sum`))

$...


$na.rm
[1] FALSE

is.function(`sum`)

[1] TRUE

is.primitive(`sum`)

[1] TRUE

class(`[`)

[1] "function"
```

Is this a feature ?


Laurent

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