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Holding Arguments in a Second Argument List


Dear MathGroup,

I have a series of procedures which manipulate a matrix. I like to define
them in this fashion.

function[args___][matrix_] := ... because then I can write lines like

matrix // function[args...] etc.

But I have to define the function so that matrix is held, and I don't want
to write Unevaluated with every use. But Attributes = {HoldFirst} only
applies to the first argument list. Is there a direct way to define the
attributes of a second argument list?

In any case, I write the routines this way.

function[args___]:=
	Function[matrix,
		Module[{}, code],
		{HoldFirst}]

and that works. The code usually changes the matrix and I display it
separately. But sometimes the operation will fail and then I would like

function[args...][matrix]

to return $Failed. But I am unable to do that. The best I seem to be able to
do is return Return[$Failed].

Here is a sample routine which just tries to return $Failed.

foo[mathgroup_] :=
  Function[mat,
    Module[{},
        If[Not[mathgroup === great], Return[$Failed]]],
    {HoldFirst}]

foo[x][mat]
Return[$Failed]

Can anyone tell me how to get rid of the Return wrapper?

Thanks

David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/



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