Re: [boost] [ANN] Phoenix-2 prerelease

From: David Abrahams (dave_at_[hidden])
Date: 2005-11-03 16:09:20

Joel de Guzman <joel_at_[hidden]> writes:

> Comments, feedback very welcome!

  Basics

  Almost everything is a function in the Phoenix library that can be
  evaluated as f(a..n), where n is the function's arity, or number of
                 ^^^^
This notation is not familiar to me.
I would have expected:

  f(a[sub 0], a[sub 1], ...a[sub [italic n]])

(using a made up quickbooky syntax)

  arguments that the function expects. Operators are also
  functions. For example, a + b is just a function with arity == 2 (or
  binary). a + b is the same as add(a, b), a + b + c is the same as
  add(add(a, b), c).

I don't know if remarks like

   Amusingly, functions may even return functions. We shall see what
   this means in a short while.

assume a background that's compatible with your use of the lambda
symbol on that page with no explanation.

   The expression arg1 % 2 == 1 evaluates to a lambda function. arg1
   represents an unsupplied argument. 

I would say

  arg1 is a placeholder for an argument to be supplied later

or if you need a short term for such a thing,

  arg1 is lazy argument---a placeholder for an argument to be
  supplied later

  However, in this document and in the examples and tests provided,
  don't be surprised to see the first and second steps
  juxtaposed.
            ^
     in order to illustrate the complete semantics of Phoenix
     expressions

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com