Tables as vectors weirdness

[Andrew Lentvorski <bsder@...>]

I'm just trying out Lua.  I'm liking a lot of things; however, the use 
of tables as vectors is just perplexing:

Lua 5.1.2  Copyright (C) 1994-2007 Lua.org, PUC-Rio
> t = { 1,1,2 }
> = # t
3
> t1 = {}
> = # t1
0
> t1[0] = 12
> = # t1
0

The Lua manual states:
"The length of a table t is defined to be any integer index n such that 
t[n] is not nil and t[n+1] is nil"

But even *that* clearly isn't the case since # for an empty vector is 0 
(which is nil).  So, even the Lua definition of # violates its 
preconditions.

Yes, I'm a "0 is the only real starting index" bigot.  This bugs me a 
little, but not hugely.  I figure I'll get over it.

Here's what really bugs me:
If I thinking about starting and ending indicies is actually relevant, 
the fault is in the programming language.

I don't want to have to *care* about a vector index start *or* end.  It 
should be completely opaque.  The failure is that tables as vectors have 
whacky behavior:

> t = {1, 2, 3}
> for i,v in ipairs(t) do print(i, v) end
1       1
2       2
3       3
> t[4] = 4
> for i,v in ipairs(t) do print(i, v) end
1       1
2       2
3       3
4       4
> t[6] = 6
> for i,v in ipairs(t) do print(i, v) end
1       1
2       2
3       3
4       4
> t[5] = 5
> for i,v in ipairs(t) do print(i, v) end
1       1
2       2
3       3
4       4
5       5
6       6
> t3 = {[2]=2, [3]=3}
> = # t3
0

Yeah, I understand the model in terms of the underlying implementation. 
 However, I shouldn't have to think about this.

This is not behaving as a vector in the sense that anybody coming from 
*any* other language is used to.  The fact that the extension is "nil" 
for a numeric type is going to be a surprise.  The fact that if I assign 
to [0], ipairs will ignore it is a suprise.  The fact that ipairs() 
stops at the first nil will be a surprise.  The fact that ipairs() can 
pick up multiple extra entries from the assignment of a single entry is 
a surprise.

In short, using "vectors" in Lua is a minefield of weirdness for new 
folks.  Either the semantics need to be cleaned up, or it really needs 
to be split out into a separate syntactic structure/system/etc.

While I like quite a bit of Lua, this is enough to make me very 
concerned about what other things are lurking in the language.  Given 
the weirdness of "vectors", what am I likely to find with "strings"?

I don't like that feeling.

-a