# Specify hash function used by \`hash()\`?
**URL:** https://discourse.julialang.org/t/specify-hash-function-used-by-hash/3091
**Category:** General Usage
**Created:** [April 6, 2017, 3:10pm UTC](https://discourse.julialang.org/t/specify-hash-function-used-by-hash/3091 "2017-04-06T15:10:47Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@kevbonham](https://discourse.julialang.org/u/kevbonham)
#### Post date: [April 6, 2017, 3:10pm UTC](https://discourse.julialang.org/t/specify-hash-function-used-by-hash/3091/1 "2017-04-06T15:10:48Z")
I’m new to the idea of hash functions, so please forgive me if this is a naive question, but I’m wondering if there’s a way to specify the hash function and seed used with `hash()`. I made a julia implementation of [a tool](https://github.com/marbl/Mash/) called “Mash” that uses hashes to compare genome signatures.
In order to make this [interoperable](https://github.com/marbl/Mash/issues/27) with the other Mash implementations (eg so signatures generated from my implementation matches the signatures from the others), I gather I need to use the same hash function, but I’m not sure quite how to do that.
I [see that](http://docs.julialang.org/en/stable/stdlib/base/#Base.hash):
> The optional second argument h is a hash code to be mixed with the result
but I don’t think that this is what I’m looking for (is it?).
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### Author:  [@kevbonham](https://discourse.julialang.org/u/kevbonham)
#### Post date: [April 6, 2017, 4:58pm UTC](https://discourse.julialang.org/t/specify-hash-function-used-by-hash/3091/2 "2017-04-06T16:58:19Z")
Never mind - looks like what I need to do in this case is use [Murmur3.jl](https://github.com/rjagerman/Murmur3.jl) instead.