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| Computers Forum Index » Computer Languages (Smalltalk) » Why doesn't smalltalk use RPN? |
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Message |
| Guest |
 Posted: Sat Jun 24, 2006 1:31 am |
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I just installed gnu smalltalk and i'm going through the tutorial (I
gave up on squeak for the time being as the multimedia is being a
distraction). One thing strikes me is that though it's somewhat like
forth in that a noun precedes a verb (postfix syntax), the mathematical
operations are algebraec infix. I find this jarring. It's somewhat like
tcl, which has a lisplike prefix syntax but uses algebraec infix for
math.
I wish smalltalk used RPN for it all to be consistent. 3 4 + would've
been 3 4 as objects and send a + message to them. |
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| Bruce Badger |
| Posted: Sat Jun 24, 2006 2:28 am |
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Guest
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On Fri, 23 Jun 2006 14:31:55 -0700, casioculture wrote:
Quote: I wish smalltalk used RPN for it all to be consistent. 3 4 + would've
been 3 4 as objects and send a + message to them.
There is no spoon, er sorry, there is no operator. There are only
messages sent to objects.
every message is sent to a single receiver.
A message is made up of a selector and arguments (zero args for a unary
message).
In your example you want two objects to be the receiver. In this case,
which + method should be used? The one for 3 or the one for 4? This is
made more obvious with something like:
(SumOfMoney for: aBalance in: #EUR) 4 +
Should the + for the SumOfMoney be executed, or the + for 4?
Smalltalk syntax (what little there is) supports the message passing idea.
RPN (as nice as it is) is jarring in that context.
All the best,
Bruce |
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| Guest |
| Posted: Sat Jun 24, 2006 6:31 am |
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casioculture@gmail.com wrote:
Quote: ... forth in that a noun precedes a verb (postfix syntax), the mathematical
operations are algebraec infix. I find this jarring. It's somewhat like
tcl, which has a lisplike prefix syntax but uses algebraec infix for
math.
I wish smalltalk used RPN for it all to be consistent. 3 4 + would've
been 3 4 as objects and send a + message to them.
Hello - I found some of the syntax 'jarring' also, until I realized the
consistancy of
object (noun-like) followed by message (verb-like). The '3', and
instance of Integer Class (an object) is being sent the message, '+',
with the parameter '4', which is also an instance of Integer Class
(another object). Perhaps, it might be better to think: '3 add: 4'
which returns the result of '3' with the message 'add:' with the
argument '4', which would be '7', also an instance of Integer Class.
RPN only made sense to me when I visualized a '3' and '4' pushed to a
stack, the
seeing a '+' operator, it popped the top two elements (fetch), did the
operation (add) and pushed (store) the result back on the stack.
Smalltalk did not encourage or discourage my visualizing a 'stack'.
That is, I did not have to care about the implementation of the message
'+'. But if I cared, I could look it up.
Hope this helps,
ACG |
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