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deferred evaluation question

• To: mathgroup at yoda.ncsa.uiuc.edu
• Subject: deferred evaluation question
• From: Steve Christensen <uunet!yoda.ncsa.uiuc.edu!stevec>
• Date: Fri, 27 Apr 90 10:02:08 -0500

There are functions in Mma that do not defer evaluation when their
arguments are undefined symbols, for example N and Mod:

In[1]:= N[x]

Out[1]= x

In[2]:= Mod[m, 7]

Out[2]= m

Question:  is it possible, through rule definition or some other clever
artifice, to make functions N and Mod defer evaluation with the input
above, i.e., evaluate to N[x] and Mod[m, 7]?  Constraints:  the artifice
should have no disastrous side effects on the normal operation of N and 
Mod or on evaluation generally, and it should be substantially less 
complex than rebuilding Mathematica in Mathematica.

  - Bill MacGregor