a way to program the Common Lisp reader
Reader macros provide a way to program the Common Lisp reader, which reads s-expressions and turns them into data. A typical use is to read new data types or to provide convenient notations.
Questions tagged [reader-macro]
39 questions
18
votes
7 answers
Read macros: what do you use them for?
I'm trying to get a feel for the parts of Lisp that I haven't used very much up to now. Read macros have caught my attention at the moment. There isn't a huge amount of info about their use and it would help to see what people have done with them,…
Pinochle
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15
votes
3 answers
What advantage does common lisp reader macros have that Clojure does not have?
I have been using Clojure alot recently but I still don't understand what functionality I do not get that common lisp reader macros provide. Can explain explain this to me in simple terms?
yazz.com
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10
votes
2 answers
operator #+ and #- in .sbclrc
Anybody know what #+ and #- operators means in .sbclrc? I couldn't find it in the manual.
I see #- in .sbclrc after I installed quicklisp:
#-quicklisp
(let ((quicklisp-init (merge-pathnames "quicklisp/setup.lisp"
…
sudo
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8
votes
2 answers
Differences between Sharpsign Colon and Gensym
I've just been reading up on the sharpsign colon reader macro and it sounded like it had a very similar effect to gensym
Sharpsign Colon: "introduces an uninterned symbol"
Gensym: "Creates and returns a fresh, uninterned symbol"
So a simple…
Baggers
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7
votes
2 answers
What's the meaning of "#+" in the code of cl-mysql?
Recently I tried to read code about cl-mysql, but got stuck with the #+.
Tried to google it, but not work, so turn to here
(defun make-lock (name)
#+sb-thread (sb-thread:make-mutex :name name)
#+ecl (mp:make-lock :name name)
#+armedbear…
c0rehe110
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7
votes
3 answers
Common lisp: is there a less painful way to input math expressions?
I enjoy common lisp, but sometimes it is really painful to input simple math expressions like
a(8b^2+1)+4bc(4b^2+1)
(Sure I can convert this, but it is kind of slow, I write (+ () ()) first, and then in each bracket I put (* () ())...)
I'm…
h__
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7
votes
3 answers
Compiling Lisp code with read macros
I'm having a bit of trouble understanding what becomes of read macros when compiling a file of lisp code into a bytecode or raw assembly (or a fasl file for that matter). Or maybe I do understand it but don't know. I'm just really confused.
When you…
Seth Carnegie
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6
votes
2 answers
Why does Clojure lack user defined reader macros?
As I understand it Clojure does not expose the reader macro table or allow user defined reader macros.
From http://clojure.org/reader:
The read table is currently not accessible to user programs.
I'm just wondering if there is a definitive or…
Paul
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6
votes
1 answer
How to eval Lisp code inside a reader macro?
I'm writing my own x86-64 assembler in Common Lisp and it produces correct binary code for a subset of x86-64. I use a custom reader macro to convert assembly code to a syntax tree, and it works as expected.
What I am attempting to accomplish is to…
nrz
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6
votes
2 answers
Why don't reader macro extensions propagate to runtime (read)?
Why does the following not work?
;;;; foo.lisp
(in-package :cl-user)
(eval-when (:compile-toplevel :load-toplevel :execute)
(require :cl-interpol))
(cl-interpol:enable-interpol-syntax)
(defun read-and-eval (s)
(eval (read-from-string…
nbtrap
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5
votes
2 answers
What is the meaning of #+: and #-: in common lisp
I am reading the cl-fad/load.lisp code tonight, and I found there are symbols #+: and #-: in the front of expression or string.
What's these symbols meaning?
ccQpein
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5
votes
1 answer
Backquote in Common Lisp: read and eval
This question is somewhat replated to this and this for Elisp. Basically, how is the back-quote read and evaluated? What processes are happening? And does the standard say anything about it?
Here is what I would expect, but it doesn't happen: symbol…
mobiuseng
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5
votes
4 answers
Is there an if-clojurescript macro?
Is there a macro for Clojure and ClojureScript that would allow you to insert different expressions depending on whether the file is being compiled in Clojure or Clojurescript?
(if-clojurescript
(my clojurescript definition)
(my clojure…
Rob Lachlan
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5
votes
1 answer
Define my own read macro
There are some read macros in Common Lisp such as ' #' #P, but how can I write a read macro?
Like this:
#T"hello world"
====================>
(gettext "hello world")
Mike Manilone
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4
votes
1 answer
Common Lisp Hash-Dot #. Reader Macro
Recently, I have come across the so-called hash-dot Common Lisp reader macro and am wondering how it works and what it does. Using search engines was not of much help, so any examples, explanations and especially uses-cases are most welcome.
MadPhysicist
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