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common-lispcomparison-operators

Avoiding strange results with most comparison operators with read-from-string

I am using an implementation of common lisp called CCL and I have run into a strange issue that I do not quite understand.

When I call:

(read-from-string "(=)")

I get a list containing the equal operator:

(=)

But when I call:

(read-from-string "(<)")

I get a backslash in front of the <:

(\<)

I find this quite confusing and I am wondering if this may be specific to my implementation or is this an intended part of the spec? Why would this \ show for < and > but not =?

Is there anyway to avoid the backslash?

Solution

  • The backslash is just a presentation issue.

    When you do (mapcar #'symbol-name (read-from-string "(<)")) you probably get ("<"), so you are getting the right symbol.

    If you want, you can report this as a bug to the CCL maintainers, since this backslash is a (minor) deviation from the ANSI CL standard.