i i i i i i i ooooo o ooooooo ooooo ooooo
I I I I I I I 8 8 8 8 8 o 8 8
I \ `+' / I 8 8 8 8 8 8
\ `-+-' / 8 8 8 ooooo 8oooo
`-__|__-' 8 8 8 8 8
| 8 o 8 8 o 8 8
------+------ ooooo 8oooooo ooo8ooo ooooo 8
Добро пожаловать GNU CLISP 2.46 (2008-07-02) <http://clisp.cons.org/>
Copyright (c) Bruno Haible, Michael Stoll 1992, 1993
Copyright (c) Bruno Haible, Marcus Daniels 1994-1997
Copyright (c) Bruno Haible, Pierpaolo Bernardi, Sam Steingold 1998
Copyright (c) Bruno Haible, Sam Steingold 1999-2000
Copyright (c) Sam Steingold, Bruno Haible 2001-2008
Напечатайте :h и нажмите Ввод для получения справки.
[1]> (defmacro infix (e)
`(destructuring-bind (x f y) ,e
(funcall f x y)))
INFIX
[2]> (infix (5 + 4))
*** - EVAL: 5 не является именем функции, попробуйте какой-нибудь
символ
Имеются следующие варианты продолжения:
USE-VALUE :R1 Вы можете ввести новое значение для
использования.
ABORT :R2 Прервать главный цикл
Break 1 [3]> :r2
[4]> (infix '(5 + 4))
9
[5]>
All, I give up! :)
On 27 сен, 21:44, Mark Rathwell <[email protected]> wrote:
> > In this point I want to cite Clojure doc, that say nothing about
> > expansion and runtime, once more: "..If the operator of a call is a
> > symbol that names a global var that is a macro function, that macro
> > function is called and is passed the /unevaluated/ operand forms. "
> > So, when I write the macro function body, I expect that operands are
> > unevaluated when my body is executed to get an expanded form (finally
> > expanded), that will be executed afterward to get a result (at
> > runtime, as you say). But this is not the case in the very first
> > example:
>
> Yes, it is the case. The operands are not evaluated in the expansion
> of the macro call, they are evaluated when that expanded code is
> executed at run time.
>
> > user=> (defmacro infix [e] `(let [[x# f# y#] ~e] (f# x# y#)))
> > #'user/infix
> > user=> (infix (5 + 4))
> > java.lang.ClassCastException: java.lang.Integer cannot be cast to
> > clojure.lang.IFn (NO_SOURCE_FILE:0)
>
> > I insist that expansion is not quite correct. Am I right?
>
> No, you are incorrect. The expansion happens as would be expected,
> and is completely consistent with the documentation. If you use
> macroexpand here, it is clear what is going on. The expansion of your
> macro contains a call to a function '5', which is an integer, and
> cannot be cast to a function. As I stated previously, you want a list
> here, not a function call.
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