I expect that each time I call :viral_load, it takes whatever
value :epitopes or :mutations has at that point in time, so I can
indeed write a function outside of the map that does the calculation,
but I found the idea of an embedded function neat.
This works as long as there is just one function in the model that
describes how epitopes and mutations translates to viral load.
However, if you would want to do something like an evolvable trade-off
between epitopes and mutations in viruses, you would like to be able
to store the functions inside each virus.
On Dec 9, 8:40 pm, ataggart <alex.tagg...@gmail.com> wrote:
> On Dec 9, 10:20 am, bOR_ <boris.sch...@gmail.com> wrote:
>
>
>
>
>
> > Hi all,
>
> > I want to make a hash-map where the value of one key depends on the
> > values of other keys in the hash-map. Is there a way to do this,
> > without needing an external reference to the hash-map?
>
> > {:a 1 :b 2 :c #(+ :a :b)}
>
> > Similarly, when filling a struct, I often want to refer to the bits I
> > already have filled in. I solve that now by just embedding the (struct
> > mything.. in a let, and just use the serial nature of let to calculate
> > for example c from a and b. Is there a way that while filling a struct
> > I can refer to it?
>
> > I would like to do this
>
> > (defstruct virus :epitopes :mutations :viral_load)
> > (def myvirus (struct virus 3 5 (+ (* 0.1 :epitopes) (*
> > 0.2 :mutations))))
>
> > Instead of
>
> > (defstruct virus :epitopes :mutations :viral_load)
> > (let [epitopes 3
> > mutations 5
> > viral_load (+ (* 0.1 epitopes) (* 0.2 mutations))]
> > (def myvirus (struct virus epitopes mutations viral_load))
>
> > As you can see there is some room for being more concise and compact
> > if you can refer to keys in the same hash-map or struct, even if the
> > hash-map / struct is still being constructed.
>
> Do you expect that modifying the values of :epitopes or :mutations
> should be reflected in the value of :viral_load? If not, then you
> could just write a custom function that creates virus instances
> instead of using struct, e.g.:
>
> (defn viral-load [epitopes mutations]
> (+ (* 0.1 epitopes) (* 0.2 mutations)))
>
> (defn make-virus [epitopes mutations]
> (struct virus epitopes mutations (viral-load epitopes mutations)))
>
> If you *do* want :viral_load to reflect changes in the other values,
> then I'd say you shouldn't include it in the struct. Actually, either
> way this seems to be a caching mechanism which is both orthogonal to
> the domain, and tends to be more trouble than it's worth in the long
> run. In short, smells like OO instead of FP, but I could be wrong.
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