cachedfunction.jl

cachedfunction.jl

# basically a type stable version of memoize.jl with a 1-element dict/cache
# it would be nice however to be able to only call cachedf = cache(f)
# such that cachedf would be typle stable.
# so far i have no idea how to achieve this

mutable struct CachedFunction{F, I, O}
    f::F
    in::I
    out::O
end

cache(f, in...) = CachedFunction(f, in, f(in...))

function (cf::CachedFunction)(in...)
    if (cf.in ≠ in)
        cf.in = in
        cf.out = cf.f(in...)
    end
    return cf.out
end

f(x) = (sleep(1); x*x)  # f is generic
f_cached = cache(f, 0)  # f_cached is no more generic :(

@time f_cached(0)
@time f_cached(1)
@time f_cached(1)