Re: [stack] adding construction to Joy-like languages

On Dec 29, 2008, at 10:05 PM, John Nowak wrote:

> Something marginally more useful:
>
>   discriminant = 3g [|2nd sq, [|1st, 3rd|] * 4 *|] -
>
> Useful? I'm not sure. The need to group things into a single vector
> all the time means it is still less convenient than the FP version...
> This is especially if we use an infix syntax (e.g. 'f g h == g:[f,
> h]') like J's monadic hook:
>
>   discriminant = (sq 2nd) - 4 * 1st * 3rd  -- all associate right

I suppose I could be more fair in my comparison; I managed to throw  
out all the benefits of the concatenative programming style in my  
example as I was doing a direct FP translation. Here's a better version:

   3g [|2nd sq, 4 * *|] -

Compare to what you'd probably write in Factor now:

   [sq swap] dip 4 * * -

I think the first version is better. It's clear that you're dealing  
with three values, clear you're squaring the second, clear you're  
getting two results and then taking the difference, etc.

I can't help but think there's some good way to combine FP with Joy- 
style languages. I think using More-style vectors as the primary data  
structure may be a good start.

- John