How to read user input in Lisp

lisp common-lisp lispworks
chope_chope picture chope_chope · Oct 3, 2014 · Viewed 11.5k times · Source

I'm very new to Lisp and am trying to write a program that simply asks a user to enter 3 numbers and then sums them and prints the output.

I've read that you can you a function like:

(defvar a)

(setq a (read))

To set a variable in Lisp, but when I try to compile my code using LispWorks I get the following error:

End of file while reading stream #<Concatenated Stream, Streams = ()>

I feel like this should be relatively simple and have no idea where I'm going wrong.

Answer

Mark Karpov picture Mark Karpov · Oct 3, 2014

I've not worked with LispWorks, so it's only a guess.

When compiler traverses your code it gets to the line (setq a (read)), it tries to read input, but there is no input stream while compiling, thus you get an error.

Write a function:

(defvar a)

(defun my-function ()
  (setq a (read))

It should work.

Related questions

How to create and write into text file in Lisp

I want to know, how to create and write text file in lisp. I just want to write simple line like: "break 1" "break 2" I am using LispWorks IDE on Window 7

Read More
What's the best way to learn LISP?

I have been programming in Python, PHP, Java and C for a couple or years now, and I just finished reading Hackers and Painters, so I would love to give LISP a try! I understand its totally diferent from what …

Read More
Check if item is in a list (Lisp)

What's a simple way to check if an item is in a list? Something like (in item list) might return true if item=1 and list=(5 9 1 2) and false if item=7

Read More