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partially delayed evaluation

  • To: mathgroup at
  • Subject: [mg13421] partially delayed evaluation
  • From: john at (John M. Dlugosz)
  • Date: Thu, 23 Jul 1998 03:33:16 -0400
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f[m,n] := (
   f[m,n] :=  Function[countone[p1]];  (* remember *)

When f is computed, it also records a special case as a "cache" for next
time, as illustrated early on in the Big Book.

However, I don't just want to return the computed value p1, so I can't 
say   f[m,n]=p1 .  I also want it to have a run-time effect, so for 
simplicity I defined the function countone which does the effect and 
returns its argument unchanged.

So, I want to build a function which when called calls countone, but the
argument p1 has to be evaluated when the Function is built.

I see this being done with low-level list manipulation so I can control 
just what gets evaluated ahead of time and what doesn't.

Could someone please show me just how to do this?



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