[Cuis] Left arrow and up arrow characters

[Juan Vuletich]

David Graham wrote:
> One of the first things that I noticed in Cuis, was that it uses left 
> arrow for assignment and up arrows for return, just like what you see 
> in the Blue Book(1).  I ran into a small problem with my "legacy" :) 
> file naming standard ( underscores for separation ) and Juan helped me 
> out with the following bit of advice:
>
> > Simply evaluating 'StrikeFont useUnderscore'displays the ASCII ^ and _
> > glyphs. If you ever want to go back to left and up arrow, evaluate
> > 'StrikeFont useLeftArrow'. I included both sets of glyphs so everybody can
> > choose.
>
> > Please note that this doesn't affect the parser. In any case both _ and :=
> > are valid for assignment, but not for use in selectors or variable names.
> > Preferences #allowUnderscoreSelectors and #allowUnderscoreAssignments give
> > you some control over this. If you set #allowUnderscoreSelectors to true
> > and #allowUnderscoreAssignments to false, you get the standard behavior in
> > many Smalltalks, where the underscore can be part of selectors or variable
> > names. In this case, if you modify existing methods, you need to change
> > assignments to be := so they will compile.
>
> I was little curious why the smalltalk creators picked those 
> characters and discovered that the left arrow was used for assignment 
> in Xerox's Mesa language, and in turn the Xerox Alto computer had a 
> key with a left arrow.  Choosing these for smalltalk is obvious when 
> you see the keyboard:
>
>
> More pictures of the Alto can be found here (use the zoom feature to 
> get a closeup of the keyboard):
> http://www.computerhistory.org/revolution/input-output/14/347/1520?position=0
>
>
>
> (1) http://stephane.ducasse.free.fr/FreeBooks/BlueBook/

The left and up arrows were part of the early 1963 ASCII standard. See 
http://www.cs.tut.fi/~jkorpela/latin1/ascii-hist.html (scroll down to 
half of page, CIRCUMFLEX ACCENT and LOW LINE). It was also in my first 
computer, the Radio Shack Coco2: 
http://en.wikipedia.org/wiki/File:Cocobvdg.png , and also on the 
Commodore 64 and many other machines of that time.

But yes, the main reason to keep those glyphs is to honor Smalltalk-80. 
I also think that Smalltalk code looks better with them.

Cheers,
Juan Vuletich