Re: [stack] Fwd: [Factor-talk] cleave, 2cleave, and spread

John Nowak <[email protected]> wrote:
> Daniel Ehrenberg wrote:
>  > though, I think a dup/swap/dip/drop base would be easier to work with
>  > in a statically typed language.

I think that's going to have to depend on the meaning of "easy to work with".

>  Absolutely; they're simple, direct, and efficient to implement.

In other words, you're looking from the perspective of the compiler
writer (especially a type inferencing compiler).

From a programmer's perspective, the simplest base will depend on the
type of programming. This is why I so much liked the stack shuffle
notation instead of the classic named stack rearrangement words; they
replace a bunch of executable concepts with a single non-executing
pattern.

BUT... These words are also a replacement for a base, and they would
be useful for writing code where parallel dataflow is the central
concept.

> Of course, it's easy to imagine reducing this list. For example:
>     drop  :: A b -> A
>     blort :: A b c [A -> D] -> D c b b

You have read http://tunes.org/~iepos/joy.html, right? If I'm reading
you right, the big difference between your basis and his bases is that
yours is designed to be typed (whoops, and that it doesn't enlist). In
his terms, I think your combinator is:

[C] [B] [A] blort == A [B] [C] [C]

>  And from this we can derive the standard functions as such:
>     swap = [] blort drop
>     dup  = swap [] blort
>     nip  = swap drop
>     dip  = [] swap blort drop nip
>     i    = [] dip drop
>     ...

>  There is possibly a cleaner typed two function base than this; it's
>  just my first stab at it. I am not sure though there is a cleaner base
>  where only one of the two functions is a combinator.

I'm not sure what you'd define as "cleaner", but I suspect a smaller
number of inputs and outputs would qualify.

>  - John

-Wm