Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!tut.cis.ohio-state.edu!magnus.ircc.ohio-state.edu!murthy
From: murthy@magnus.ircc.ohio-state.edu (Murthy S Gandikota)
Newsgroups: comp.lang.lisp
Subject: Is MAP meant to operate on strings?
Message-ID: <1991Feb23.205613.14321@magnus.ircc.ohio-state.edu>
Date: 23 Feb 91 20:56:13 GMT
Sender: news@magnus.ircc.ohio-state.edu
Organization: The Ohio State University
Lines: 31
Originator: murthy@left.magnus.ircc.ohio-state.edu
Nntp-Posting-Host: left.magnus.ircc.ohio-state.edu




This could be a naive question, but what the heck I will go ahead.

(map 'string #'(lambda (x) #\h) "replace every char with h")

==> "hhhhhhhhhhhhhhhhhhhhhhhhh"

Whereas if I try to do

(map 'string #'(lamda (x) (if (equal x #\e) #\f)) "I want to replace e
with f")

==> Error:  ARG not a character 

(this is all the error informatin my LISP machine displays)

Can anyone point out why the error happens?

(BTW, I have tried another way which uses an explict do loop and
checks: (string= (string (char x i)) "e") and then replaces using
(setf (char x i) "f") where x is the input string and i is the index,
i.e. the position inside the string. Also, the DOTIMES needs to loop
(LENGTH x) times to make the substitution, so after all, it is not
that bad. But, I still wonder what's wrong with the using MAP)


Thanks

Murthy Gandikota