# Letting users change the default types

**URL:** <https://discourse.julialang.org/t/letting-users-change-the-default-types/66781>\
**Category:** Internals & Design\
**Created:** [August 21, 2021, 4:13pm UTC](https://discourse.julialang.org/t/letting-users-change-the-default-types/66781 "2021-08-21T16:13:34Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![jling](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jling/32/212909_2.png) [@jling](https://discourse.julialang.org/u/jling)\
**Post date:** [August 21, 2021, 4:21pm UTC](https://discourse.julialang.org/t/letting-users-change-the-default-types/66781/2 "2021-08-21T16:21:09Z")

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> [@Lucas\_Queiroz](#):
>
> Given that for some users, the `Big` types might be more adequate than the `64` types, why not let the user decide which one of them is Julia’s default?

how does this affect libraries? does each module has its own default type? What about calling other functions from other module?

The fact that most libraries are written size-agnostic, as you have noted, means users can do what they think is the best.

Check out:

> [@\[ANN\] SafeREPL: use BigInt by default at the REPL](https://discourse.julialang.org/t/ann-saferepl-use-bigint-by-default-at-the-repl/41271):
>
> With Julia 1.5 around the corner, I’m happy to present [SafeREPL](https://github.com/rfourquet/SafeREPL.jl), a little experimental package which by default interprets Int and Int128 REPL literals as BigInt, and Float64 literals as BigFloat: julia\> using SafeREPL julia\> factorial(40) 815915283247897734345611269596115894272000000000 julia\> sqrt(2.0) 1.414213562373095048801688724209698078569671875376948073176679737990732478462102 julia\> c = 299\_792\_458; c^3 # the cube of the speed of light can even be computed safely! 26944002417373989…

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