Just curious. is there a reason for using string eval here? Why not: 
print reduce { $a + $b } 1,2,3;

[download]
Anyway, if I change it to: 
print reduce{ print "a = $a, b = $b\n"; eval "$a + $b" } 1,2,3,4;

[download]
I get: 
a = 1, b = 2
Use of uninitialized value in concatenation (.) or string at 1 line 4.
a = , b = 3
Use of uninitialized value in concatenation (.) or string at 1 line 4.
Use of uninitialized value in concatenation (.) or string at 1 line 4.
a = , b = 4
Use of uninitialized value in concatenation (.) or string at 1 line 4.
4
which explains the 3 that you're seeing. Apparently the eval is returning undef.

No further ideas, I'm afraid. Hmmm... maybe an optimalization that's over optimizing?

Liz

Update
Mine was with the 20581 snapshot (5.8.1-RC5 to be, List::Util 1.11)

Update:
Graham Barr wrote on p5p on August 14, 2003: 

This is close, but not right as it will result in $a being modified when
the sub returns. Later today I will release 1.12 with a fix for this.
while referring to List::Util.

In reply to Re: An anomaly with List::Util::reduce and/or eval? by liz
in thread An anomaly with List::Util::reduce and/or eval? by BrowserUk

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