Re: [Felix-language] function product

[john s. <sk...@us...>]

On 28/04/2015, at 11:26 AM, john skaller wrote:

> However \prod (f,g,h) still can't be defined, i have ravel (f,g,h) in the 
> library for up to 5 cases.

I'm giving up: I'm defining it directly in the compiler.
And sum too.

Now, to get the mediating morphism of a product, <f,g> for many n,
we note that

	<f,g> = x.dup2.( \prod (f,g) )

So the aim is to now define:

	fun dup[N,T] (x:T):T^N  => x,x,x,...,x // n times

which is just an array length N filled with x's...
I guess that is already in the library under another name.
(as an array constructor?) The function is also called \diag
printed as a \delta. 

The sum version is called \nabla, it takes n x's and produces
a single x.

--
john skaller
sk...@us...
http://felix-lang.org