Julia: Piping operator | with more than one argument

Question

I am attempting to pass multiple arguments to the built in piping operator in Julia `|>`. I would like something that works like this: ``` join([randstring() for i in 1:100], " ") ``` However, using the piping operator, I get an error instead: ``` [randstring() for i in 1:100] |> join(" ") ``` I am pretty sure this is a feature of multiple dispatch with join having its own method with `delim` in the `join(strings, delim, [last])` method being defined as `delim=""` when omitted. Am I understanding this correctly? Is there a work around? For what is is worth the majority of my uses of piping end up taking more than one argument. For example: ``` [randstring() for i in 1:100] |> join(" ") |> replace("|", " ") ```

Accepted Answer

Metaprogramming to the rescue!

We'll use a simple macro to allow piping to multi-input functions.

```
    using Pipe, Random
    @pipe [randstring() for i in 1:100] |> join(_, " ")
```

So after calling the Pipe package all we're doing is

using the @pipe macro

designating where where to pipe to with the underscore ("_") [if the function only takes one input we don't need to bother with the underscore: e.g.

```
 @pipe 2 |> +(3,_) |> *(_,4) |> println   
```

will print "20"]

See here or here for more formal documentation of the Pipe package (not that there's much to document :).

Julia: Piping operator |> with more than one argument

Solution

Problem