Re: [colorforth] explicit vs. implicit

[Mark Slicker <maslicke@xxxxxxxxxxx>]

The previous message was lacking information, it happend to work
since the operators were commutative. Forth builds its trees along the
right most edge. So the proper example is:

Take the expression:

x*(y+z)

in Lisp:

(* x (+ y z))

in Forth ( x y z ):

+ *

The tree representing the result takes form of:

     *
   /   \
  x     +
      /   \
     y     z

In thinking about this more, the comparison might break down because Forth
has the ability leave results on the stack. For the purposes of this
example, Forth can build a sequence of trees:

+ * dup

results in:

     *            *
   /   \        /   \
  x     +      x     +
      /   \        /   \
     y     z      y     z

now if I try:

+ * dup +

I get:

       ____+_____
      /          \
     *            *
   /   \        /   \
  x     +      x     +
      /   \        /   \
     y     z      y     z


In lambda languages the method of reusing a subtree is to create a binding
or abstraction of an expression.

Mark

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