Re: [PoC] Tables aren't Lua's only data structure.

[Dirk Laurie <dirk.laurie@...>]

2015-04-17 6:17 GMT+02:00 Soni L. <fakedme@gmail.com>:

> I present you Lua's second data structure: The stack.

I tried something of the kind in the 'tuple' sublibrary of the 'xtable'
library that John Hind and I developed at a stage when there was
some unhappiness about the table library. In the meantime that
library has been substantially improved.

   https://github.com/dlaurie/xtable

We used a mixture of C and Lua.

>From the documentation:

   The tuple sublibrary

   This library provides basic functions for manipulating tuples, i.e.
   immutable lists of values on the runtime stack. The functions are
   supplied in the table xtable.tuple.

   Since no table accesses are involved, and the return values are in the
   same stack as the vararg list, often in the same positions, tuple
   functions are fast.

   Tuples in Lua live an ephemeral life as vararg lists or multiple return
   values, and need to be passed to coroutines or packed into tables to
   achieve permanence. The functions cache and iter, written in Lua, serve
   as sample applications.

 xtable.tuple.cache(...)

   Returns a function that, when called, will return the given values.

xtable.tuple.iter(...)

   Returns an iterator function that, in a generic for loop, will return
   the given values one by one.

xtable.tuple.keep(count,...)

   Returns count arguments, starting at the first extra argument. As in
   the case of select, a negative number indexes from the end (-1 is the
   last argument).

xtable.tuple.map(ft,...)

   Each return value is the result of ft applied to the corresponding
   value in the tuple.

   "Applying" means indexing if ft is a table and calling if ft is a
   function, which is assumed to be unary with one return value.

xtable.tuple.collect(...)

   Concatenates all its arguments, respecting metamethods.