On 25.02.2018 14:38, Daniel.Sun wrote:
Hi all,
I propose to introduce Concatenative Method Calls to Groovy. It can
make code more readable, for example:
Currently we write method calls like:
y = foo(x)
z = bar(y)
w = baz(z)
OR
w = baz(bar(foo(x)))
Concatenative Method Calls(inspired by [1]):
w = x => foo => bar => baz
Any thoughts?
Cheers,
Daniel.Sun
[1] https://en.m.wikipedia.org/wiki/Concatenative_programming_language
I think if we want to become a concatenative programming language, we
should first try to allow tacit programming... I would not start with
composition here. You start with how to actually reference a function in
the first place. If you go with method references you can do some things:
this.&baz << this.&bar << this.&foo (x)
Or with a lambda style:
this::baz << this::bar << this::foo (x)
And you can even leave the (x) to get the composition. And you can do
even something like
def barfoo = this::bar << this::foo
this::baz << barfoo (x)
In your variant I find it questionable if you can do without the "this".
Otherwise you will have an overlap between local variables and methods.
So what I would like to see is 1-n more complex examples, that do not
concentrate on one line only. It should contain a "reference" to method,
that is no on "this"; it should show how the shadowing by a local
variable is supposed to be handled (if any); and it show how arguments
are handled, especially for different arities... After that we can talk
about if that is really better readable.
I actually do think our method references need rework in how they are
formed, because they are actually functionally incomplete, as can be
easily seen in this example:
class X {
private bar(){1}
def b = this.&bar
}
println new X().b()
class Y extends X {}
println new Y().b()
That's why I said I would prefer cleaning those elements up and make
them actually working correctly before we go to composition in the next
step and then talk maybe about a concatenative programming language and
how much that clashes with command expressions ;)
bye Jochen
