title: "Dot Pipe"

author: "John Mount"

date: "`r Sys.Date()`"

output: rmarkdown::html_vignette

vignette: >

[`%.>%` dot arrow pipe](https://winvector.github.io/wrapr/reference/dot_arrow.html) is a strict pipe with intended semantics:

That is: `%.>%` does not alter any function arguments that are not explicitly named. `%.>%` is designed to be explicit and simple.

The following two expressions should be equivalent:

```{r pipe1s}

The notation is quite powerful as it treats pipe stages as expression parameterized over the variable

"`.`". This means you do not need to introduce functions to express stages. The following is

a valid dot-pipe:

```{r pipe1}

The notation is also very regular in that many variations of expression work as expected. Example:

```{r pipe2}

Regularity can be a *big* advantage in teaching and comprehension. Please see ["In Praise of Syntactic Sugar"](https://win-vector.com/2017/07/07/in-praise-of-syntactic-sugar/) for discussion.

The dot arrow pipe has S3/S4 dispatch (please see ["Dot-Pipe: an S3 Extensible Pipe for R"](https://journal.r-project.org/archive/2018/RJ-2018-042/index.html)).

However as the right-hand side of the pipe is normally held unevaluated, we don't know the type except in special

cases (such as the rigth-hand side being referred to by a name or variable). To force the evaluation of a pipe term,

simply wrap it in .().

A detail of R-style pipes is the right argument is held unevalauted (unless it is a name), so we can't always use the class of the right hand side to dispatch. To work around this we suggest using `.()` notation, which in the context of the pipe means "evaluate early." An example is given below:

```{r peager}