Re: [Lua-users-stdlib] Upheaval (blame Jamie Webb!)

[Jamie W. <j...@jm...>]

On Sunday 01 February 2004 19:03, Reuben Thomas wrote:
>         the functionalised operators +, -, .. &c. -- not sure how best to
>               -- include these, e.g. how to name them, how general they
>               -- really should be (arity &c.)

Naming: yeah, dunno. Arity: I decided it made sense only for commutative 
operators to be variadic.

> The following I plain don't understand:
>
> 	function std.getter(name)      -- what's this for?
> 	function std.method(name, ...) -- what's this for?
> 	function std.bind_method(t, m) -- what's this for?

Say I have a list of objects and I want to get a list of those which have 
attribute foo = true:

footrue = std.filter(std.getter("foo"), objects)

Say I want to call method swizzle(5) on each of a list of (maybe polymorphic) 
objects:

results = std.map(std.method("swizzle", 5), objects)

bind_method() as I said is just a convenience. It means I can write 
std.bind_method(object, "method", ...) rather than std.bind(object.method, 
object, ...). It just happens that I had some code where I needed to do that 
a lot.

> I'm dubious about the following:
>
> 	function std.map_tbl(f, t)     -- it is really wise to map over a table?
> 	function std.filter_tbl(f, t)  -- these should only be used on
> lists/arrays IMO

Why not? Changing the keys is maybe not such a great idea, but there doesn't 
seem to be any reason not to map/filter over the values. Obviously the order 
is undefined, but that's just expected from any operation on tables. I don't 
really see why one shouldn't map (most likely injections) over sets either.

> 	function std.conjunction(...)  -- this seems a bit specialised;
>                                           it's really reverseMap composed
>                                           with functionalised "and"

Fair enough. I just didn't think of that; I've never come across reverseMap 
before. I don't see it in your library though.

 -- Jamie Webb