# \`code\_warntype\` understanding

**URL:** <https://discourse.julialang.org/t/code-warntype-understanding/48627>\
**Category:** New to Julia\
**Tags:** performance, type, numerics\
**Created:** [October 19, 2020, 1:50pm UTC](https://discourse.julialang.org/t/code-warntype-understanding/48627 "2020-10-19T13:50:55Z")\
**Posts on this page:** 11\
**Page:** 2

<div class="post-metadata">

**Author:** ![kristoffer.carlsson](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kristoffer.carlsson/32/22_2.png) [@kristoffer.carlsson](https://discourse.julialang.org/u/kristoffer.carlsson)\
**Post date:** [October 20, 2020, 10:30am UTC](https://discourse.julialang.org/t/code-warntype-understanding/48627/21 "2020-10-20T10:30:59Z")

</div>

I get

```julia
julia> model(2.2; settings=[1,1,1.0])
ERROR: UndefKeywordError: keyword argument pars not assigned

```

when running your code.

Edit: With updated code I get that both of these infer to `Any`.

Edit 2: I think this has something to do with inference state dependence: For example:

```julia
julia> @code_warntype M(2.2) # still Body::Any
Variables
  #self#::Core.Const(M)
  x::Float64

Body::Any
1 ─ %1 = (:pars,)::Core.Const((:pars,))
│ %2 = Core.apply_type(Core.NamedTuple, %1)::Core.Const(NamedTuple{(:pars,), T} where T<:Tuple)
│ %3 = Base.vect(1, 1, 1.0)::Vector{Float64}
│ %4 = Core.tuple(%3)::Tuple{Vector{Float64}}
│ %5 = (%2)(%4)::NamedTuple{(:pars,), Tuple{Vector{Float64}}}
│ %6 = Core.kwfunc(Main.model)::Core.Const(Main.MyTest2.var"#model#3##kw"())
│ %7 = (%6)(%5, Main.model, x)::Any
└── return %7

julia> @eval Base begin
           sum(f, a; kw...) = mapreduce(f, add_sum, a; kw...)
       end
sum (generic function with 14 methods)

julia> @code_warntype M(2.2) # still Body::Any
Variables
  #self#::Core.Const(M)
  x::Float64

Body::ComplexF64
1 ─ %1 = (:pars,)::Core.Const((:pars,))
│ %2 = Core.apply_type(Core.NamedTuple, %1)::Core.Const(NamedTuple{(:pars,), T} where T<:Tuple)
│ %3 = Base.vect(1, 1, 1.0)::Vector{Float64}
│ %4 = Core.tuple(%3)::Tuple{Vector{Float64}}
│ %5 = (%2)(%4)::NamedTuple{(:pars,), Tuple{Vector{Float64}}}
│ %6 = Core.kwfunc(Main.model)::Core.Const(Main.MyTest2.var"#model#3##kw"())
│ %7 = (%6)(%5, Main.model, x)::ComplexF64
└── return %7

```

The function I evalled is indentical to the earlier one and only serves to re-compile functions.

Before the eval we had:

```julia
  ┌ @ reduce.jl:501 within `sum'
│ │ %3 = invoke Base.:(var"#sum#216")($(QuoteNode(Base.Iterators.Pairs{Union{}, Union{}, Tuple{}, NamedTuple{(), Tuple{}}}()))::Base.Iterators.Pairs{Union{}, Union{}, Tuple{}, NamedTuple{(), Tuple{}}}, %1::typeof(sum), %2::Function, _4::Base.Generator{Base.Iterators.Zip{Tuple{Vector{Float64}, Vector{NamedTuple{(:N, :k, :p), Tuple{Int64, Float64, Float64}}}}}, Main.MyTest2.var"#2#5"{Float64}})::Any

```

after it changes to (look at return type in the end)

```julia
│ ┌ @ REPL[9]:2 within `sum'
│ │ %3 = invoke Base.:(var"#sum#865")($(QuoteNode(Base.Iterators.Pairs{Union{}, Union{}, Tuple{}, NamedTuple{(), Tuple{}}}()))::Base.Iterators.Pairs{Union{}, Union{}, Tuple{}, NamedTuple{(), Tuple{}}}, %1::typeof(sum), %2::Function, _4::Base.Generator{Base.Iterators.Zip{Tuple{Vector{Float64}, Vector{NamedTuple{(:N, :k, :p), Tuple{Int64, Float64, Float64}}}}}, Main.MyTest2.var"#2#5"{Float64}})::ComplexF64

```

Also, see the allocation difference:

```julia
julia> @btime M(2.2)
  521.423 ns (13 allocations: 480 bytes)
-1.7454668760152625 + 4.251554706912252im

julia> @eval Base begin
       sum(f, a; kw...)= mapreduce(f, add_sum, a; kw...)
       end
sum (generic function with 14 methods)

julia> @btime M(2.2)
  440.561 ns (6 allocations: 256 bytes)
-1.7454668760152625 + 4.251554706912252im

```

---

<div class="post-metadata">

**Author:** ![misha\_mikhasenko](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/misha_mikhasenko/32/5060_2.png) [@misha\_mikhasenko](https://discourse.julialang.org/u/misha_mikhasenko)\
**Post date:** [October 20, 2020, 12:01pm UTC](https://discourse.julialang.org/t/code-warntype-understanding/48627/22 "2020-10-20T12:01:33Z")

</div>

Hi @kristoffer.carlsson, thanks for checking

> [@kristoffer.carlsson](#):
>
> inference state dependence

what does it mean?

---

<div class="post-metadata">

**Author:** ![misha\_mikhasenko](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/misha_mikhasenko/32/5060_2.png) [@misha\_mikhasenko](https://discourse.julialang.org/u/misha_mikhasenko)\
**Post date:** [October 20, 2020, 12:03pm UTC](https://discourse.julialang.org/t/code-warntype-understanding/48627/23 "2020-10-20T12:03:11Z")

</div>

In the example below, if I comment the line marked with `# !!!!!!!!!!` I get `::Any`.

```julia
module MyTest2
    using Parameters
    function build_model(list_of_settings)
        function model(x; pars)
            return sum(p*single_term_model(x; settings=s)
                for (p,s) in zip(pars, list_of_settings))
        end
        return model
    end
    function single_term_model(x; settings)
        @unpack N, k, p = settings
        value = sum((k*x)^i*cis(i*p*x) for i in 1:N)
        return value
    end
    export build_model
end

using .MyTest2

const list_of_settings = [(N=3,k=0.1,p=0.3),
                    (N=5,k=0.5,p=0.3),
                    (N=7,k=0.2,p=0.3)]
#
#!!!!!!!!!!
# @code_warntype MyTest2.single_term_model(2.2; settings=list_of_settings[1]) # correct! Complex{Float}
#!!!!!!!!!!
# 
const model = build_model(list_of_settings)

@code_warntype model(2.2; pars=[1.0, 1.0, 1.0]) # Body::Any

```

As soon as I uncomment the line, I get `Body::Complex{Float64}`

---

<div class="post-metadata">

**Author:** ![misha\_mikhasenko](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/misha_mikhasenko/32/5060_2.png) [@misha\_mikhasenko](https://discourse.julialang.org/u/misha_mikhasenko)\
**Post date:** [October 20, 2020, 12:08pm UTC](https://discourse.julialang.org/t/code-warntype-understanding/48627/24 "2020-10-20T12:08:53Z")

</div>

It seems that one needs to call the internal function once to make it’s type inferred.  
Should I do it for every internal function… ?

---

<div class="post-metadata">

**Author:** ![kristoffer.carlsson](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kristoffer.carlsson/32/22_2.png) [@kristoffer.carlsson](https://discourse.julialang.org/u/kristoffer.carlsson)\
**Post date:** [October 20, 2020, 12:43pm UTC](https://discourse.julialang.org/t/code-warntype-understanding/48627/25 "2020-10-20T12:43:36Z")

</div>

> [@misha\_mikhasenko](#):
>
> Hi @kristoffer.carlsson, thanks for checking
> 
> > [@kristoffer.carlsson](#):
> >
> > inference state dependence
> 
> what does it mean?

> [@misha\_mikhasenko](#):
>
> It seems that one needs to call the internal function once to make it’s type inferred.  
> Should I do it for every internal function… ?

This is pretty much what it means. The order that you inferred functions changed the result. I would classify it as an inference bug. There is some issue open about it but I can’t find it now.

---

<div class="post-metadata">

**Author:** ![misha\_mikhasenko](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/misha_mikhasenko/32/5060_2.png) [@misha\_mikhasenko](https://discourse.julialang.org/u/misha_mikhasenko)\
**Post date:** [October 20, 2020, 12:45pm UTC](https://discourse.julialang.org/t/code-warntype-understanding/48627/26 "2020-10-20T12:45:30Z")

</div>

Does this problem influence performance? E.g. when doing integration

---

<div class="post-metadata">

**Author:** ![kristoffer.carlsson](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kristoffer.carlsson/32/22_2.png) [@kristoffer.carlsson](https://discourse.julialang.org/u/kristoffer.carlsson)\
**Post date:** [October 20, 2020, 12:45pm UTC](https://discourse.julialang.org/t/code-warntype-understanding/48627/27 "2020-10-20T12:45:47Z")

</div>

I would think so, yes.

---

<div class="post-metadata">

**Author:** ![misha\_mikhasenko](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/misha_mikhasenko/32/5060_2.png) [@misha\_mikhasenko](https://discourse.julialang.org/u/misha_mikhasenko)\
**Post date:** [October 20, 2020, 12:46pm UTC](https://discourse.julialang.org/t/code-warntype-understanding/48627/28 "2020-10-20T12:46:48Z")

</div>

Annoying, but ok, I should check of it always, then. Thanks a lot.

With this the original problem is nearly resolved.  
My main confusion was due to a global variable carrying the function `model = build_model(...)`.

---

<div class="post-metadata">

**Author:** ![kristoffer.carlsson](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kristoffer.carlsson/32/22_2.png) [@kristoffer.carlsson](https://discourse.julialang.org/u/kristoffer.carlsson)\
**Post date:** [October 20, 2020, 1:15pm UTC](https://discourse.julialang.org/t/code-warntype-understanding/48627/29 "2020-10-20T13:15:22Z")

</div>

The issue I couldn’t find should be [https://github.com/JuliaLang/julia/issues/35800](https://github.com/JuliaLang/julia/issues/35800).

---

<div class="post-metadata">

**Author:** ![misha\_mikhasenko](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/misha_mikhasenko/32/5060_2.png) [@misha\_mikhasenko](https://discourse.julialang.org/u/misha_mikhasenko)\
**Post date:** [October 20, 2020, 3:38pm UTC](https://discourse.julialang.org/t/code-warntype-understanding/48627/30 "2020-10-20T15:38:59Z")

</div>

Is there a version of `sum` comprehension that does not have the issue?  
Something simple than that?

```julia
    function mysum(t::T where T<:Type, itrs::Base.Generator)
        v = zero(t)
        for it in itrs
            v += it
        end
        return v
    end    

```

---

<div class="post-metadata">

**Author:** ![misha\_mikhasenko](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/misha_mikhasenko/32/5060_2.png) [@misha\_mikhasenko](https://discourse.julialang.org/u/misha_mikhasenko)\
**Post date:** [October 20, 2020, 3:42pm UTC](https://discourse.julialang.org/t/code-warntype-understanding/48627/31 "2020-10-20T15:42:11Z")

</div>

If I am asked to select my favourite `julia` issue, perhaps, I would pick this one.  
I use `sum` everywhere in my code…

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