# Idea for setting both mutables and immutables without allocation

**URL:** <https://discourse.julialang.org/t/idea-for-setting-both-mutables-and-immutables-without-allocation/1318>\
**Category:** Internals & Design\
**Tags:** proposal\
**Created:** [January 6, 2017, 5:31am UTC](https://discourse.julialang.org/t/idea-for-setting-both-mutables-and-immutables-without-allocation/1318 "2017-01-06T05:31:55Z")\
**Posts on this page:** 1\
**Showing post:** 18

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**Author:** ![jeff.bezanson](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jeff.bezanson/32/48_2.png) [@jeff.bezanson](https://discourse.julialang.org/u/jeff.bezanson)\
**Post date:** [January 27, 2017, 7:11pm UTC](https://discourse.julialang.org/t/idea-for-setting-both-mutables-and-immutables-without-allocation/1318/18 "2017-01-27T19:11:28Z")

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> [@ScottPJones](#):
>
> As far as BigInt (and BigFloat) are concerned, I think the only way to really get good performance is to move away from trying to use a type that points at C managed memory and to change things to use an immutable type, with Julia managed memory.

I completely agree, but we would get _even better_ performance adding the ability to safely overwrite numbers instead of allocating new ones when possible, on top of that.

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