On Tue, Apr 21, 2020 at 4:44 PM Larry Garfield <la...@garfieldtech.com> wrote:
>
> On Mon, Apr 20, 2020, at 11:20 PM, Stanislav Malyshev wrote:
> > Just a small pedantry note - in a comparison section, the RFC compares
> > this syntax to function composition. But this is not function
> > composition. This is a syntax sugar for calling two functions one after
> > another, not operator that produces a function. It sounds pedantic but
> > it's rather important distinction - if |> is composition, than $foo |>
> > $bar is a new callable provided $foo and $bar are callable (but no
> > function is actually being called here!). If |> is call syntax, it's
> > actually the result of calling $bar($foo).
> >
> > So comparing it to function composition is a bit confusing. Otherwise it
> > looks OK to me, except the syntax for calling functions and methods is a
> > bit awkward, but it's not the problem of this RFC I imagine.
>
> I'm not sure I follow.  The only place composition is mentioned is in the F# 
> section, where it calls out specifically that we're implementing "pipe 
> forward" and *not* the composition operators ( >> ).  Is that unclear?

Actually it's also mentioned in the Haskell section, but as "function
concatenation" (which adds to the confusion I guess).

Speaking of Haskell, that reminded me of
http://learnyouahaskell.com/a-fistful-of-monads#walk-the-line where
the author defines a custom `-:` operator such that `x -: f` desugars
to `f x` (equivalent to how `$x |> $f` would desugar to `$f($x)` with
the RFC), which allows to write e.g. `xs -: sort -: reverse` instead
of `reverse (sort xs)` or `(reverse . sort) xs`.

-- 
Guilliam Xavier

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