Add the pipe operator |>

[jmackie]

It's a fan favourite. The "right pizza" syntax came from F# I think, and has since been copied by Elm, Elixir, et al. Although the idea of "piping" goes back way further.

In Ditto, this operator should just be syntactic sugar. The right-hand side gets called with the left-hand side as its first argument.

lhs |> rhs()
rhs(lhs)

lhs |> rhs(x, y, z)
rhs(lhs, x, y, z)

-- should we allow the right-hand-side to omit parens? Could enforce during parsing
lhs |> rhs
rhs(lhs)

The desugaring should happen when we convert the CST to the "pre" AST, which means no new cases need to be added to the typechecker.

• Add the pipe operator |> #41
• ditto-lang/tree-sitter-ditto@37271ee