Thread

*To*: mathgroup at smc.vnet.net*Subject*: [mg53238] Thread*From*: Carlo Teubner <"see signature."@example.com>*Date*: Sun, 2 Jan 2005 04:12:47 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

I'm trying to write a variant of Thread which takes into account options. That is, I want ThreadOptions[ f[{1,2}, Opt1 -> {a,b}, Opt2 -> {x,y}] ] to give {f[1, Opt1 -> a, Opt2 -> x], f[2, Opt1 -> b, Opt2 -> y]}. A first approximation I've come up with is ThreadOptions[f_[args___, opts___?OptionQ]] := Thread[f[args, Inner[Rule, Sequence@@Thread[{opts}, Rule], List]]] Now I get {f[1, {Opt1 -> a, Opt2 -> x}], f[2, {Opt1 -> b, Opt2 -> y}]} which is close. I need to get rid of the {}. The following works: ThreadOptions[f_[args___, opts___?OptionQ]] := Thread[f[args, Inner[Rule, Sequence@@Thread[{opts}, Rule], seq]]] /. seq -> Sequence However, there is a problem: now f gets evaluated before replacing the seq with Sequence objects. To get around this, I tried using Unevaluated: ThreadOptions[f_[args___, opts___?OptionQ]] := Unevaluated[Thread[f[args, Inner[Rule, Sequence@@Thread[{opts}, Rule], seq]]] /. seq -> Sequence But it doesn't work; I get: Thread::tdlen : Objects of unequal length in f[{1, 2}, {Opt1 -> a, Opt2 -> x, Opt1 -> b, Opt2 -> y}] cannot be combined. f[{1, 2}, {Opt1 -> a, Opt2 -> x, Opt1 -> b, Opt2 -> y}] I assume what's happened is that ReplaceAll has been applied to the Unevaluated expression, which has not been evaluated. Is there any way at all of Thread'ing a function, but then not evaluating it? Are there other ways of creating a ThreadOptions function? Thanks for any help. Carlo -- C Teubner t offline de dot at minus dot ...oops: "on" not "off" :)