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Re: Destructuring arguments to pure functions?

• To: mathgroup at smc.vnet.net
• Subject: [mg95787] Re: Destructuring arguments to pure functions?
• From: Bill Rowe <readnews at sbcglobal.net>
• Date: Tue, 27 Jan 2009 06:59:19 -0500 (EST)

On 1/26/09 at 5:03 AM, dreeves at gmail.com (dreeves) wrote:

>I'm curious what you all think of this idea:

>Unprotect[Integer];
>1[x_] := x[[1]]
>2[x_] := x[[2]]
>3[x_] := x[[3]]
>4[x_] := x[[4]]
>5[x_] := x[[5]]
>6[x_] := x[[6]]
>7[x_] := x[[7]]
>8[x_] := x[[8]]
>9[x_] := x[[9]]
>Protect[Integer];

Redefining built-in objects often leads to unpredictable
behavior elsewhere in Mathematica. And doing this to more
fundamental objects tends to dramatically increase the
probability of something like this happening.

>and then

>1@# + 2@# & /@ testList

>It seems to be very slow in the current version of Mathematica but
>it seems like a concise/elegant way to avoid the clunky yet
>oft-typed # [[n]] (ie, replacing it with n@# or n[#]).

There are better ways to avoid the usage of # than adding
definitions to Integer. In this particular example, you are
adding sequential pairs. This can be done without # as:

Plus@@@Partition[testList,2,1]