# Good tutorials!

**Alexis Read
**
ucapare@ucl.ac.uk

*Wed May 15 09:46:01 2002*

The arrow formalism from category theory makes a distinction between the
nodes of a graph (objects), and the arrows between nodes (morphisms).
Brian's idea for tunes treats them the same - imagine a 2D graph of nodes
and arrows: the nodes can be thought of as arrows projecting into 3D ie.
where they point is irrelevant for the task considered, they are just
there to be referenced.
The idea is that with only one atomic type rather than two, every object
has a meta-level you can use to manipulate it. ie. the arrows referencing
that particular arrow.
Alexis.
On Wed, 15 May 2002, Mario wrote:
>* Alexis Read wrote:
*>* > For those that are having trouble with arrows formalisms
*>* > http://www.haskell.org/arrows/
*>* > http://www.haskell.org/arrows/biblio.html#Hug00
*>* > Additionally if you follow the links off this you should find a GUI
*>* > toolkit based on arrows.
*>*
*>* Thanks for the links. But, could somebody please explain if the arrow
*>* formalism from the category theory actually have anything to do with the
*>* Arrow basis for Tunes?
*>*
*>*
*>*
*