Language Feature: Pipe Syntax

[mitchpaulus]

Currently thinking about adding a feature similar to pipes or fluent syntax such that a pipeline of function transformations can be built from left to right. For me, this is easier to read than nested function application.

data | filter(\ item { item.'something' == 'something' } ) | map(\ item { item.'To Something Else' })
vs.
map(\ item { item.'To Something Else' }, filter(\ item { item.'something' == 'something' }), data) )

For this to be most useful, I'd have to change the order of some of the built in function signatures.

[mitchpaulus]

This issue can serve to document my thoughts through the design of this.

Ideally, this gets added to the grammar as another simple recursive operator like

expression : expression PIPEOPERATOR expression

This would require type checks at runtime, which is fine. The only issue is how to handle piping into a function that takes more than one argument. For example, I'd like to be able to do something like:

# filter function has 2 parameters, list and function. 
list | filter(\ item { item == 1 }) 

However, as it stands, the function application would throw an exception for not having the required number of arguments.