# Why is this type inference failed
**URL:** https://discourse.julialang.org/t/why-is-this-type-inference-failed/60077
**Category:** General Usage
**Created:** [April 27, 2021, 2:42am UTC](https://discourse.julialang.org/t/why-is-this-type-inference-failed/60077 "2021-04-27T02:42:18Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@N5N3](https://discourse.julialang.org/u/N5N3)
#### Post date: [April 27, 2021, 2:42am UTC](https://discourse.julialang.org/t/why-is-this-type-inference-failed/60077/1 "2021-04-27T02:42:18Z")
```julia
function interfer_test(
obj::T,
Ls::NTuple{2,<:Integer},
) where {T}
CT = complex(T)
mem_init = ntuple(_ -> zeros(CT, Ls), Val(4))
end
@code_warntype interfer_test(1,(100,100))
```
The above code returns
```julia
Variables
#self#::Core.Const(interfer_test)
obj::Int64
Ls::Tuple{Int64, Int64}
#33::var"#33#34"{Tuple{Int64, Int64}, DataType}
mem_init::NTuple{4, Matrix{_A} where _A}
CT::Type{Complex{Int64}}
Body::NTuple{4, Matrix{_A} where _A}
1 ─ (CT = Main.complex($(Expr(:static_parameter, 1))))
│ %2 = Main.:(var"#33#34")::Core.Const(var"#33#34")
│ %3 = Core.typeof(Ls)::Core.Const(Tuple{Int64, Int64})
│ %4 = Core.typeof(CT::Core.Const(Complex{Int64}))::Core.Const(DataType)
│ %5 = Core.apply_type(%2, %3, %4)::Core.Const(var"#33#34"{Tuple{Int64, Int64}, DataType})
│ (#33 = %new(%5, Ls, CT::Core.Const(Complex{Int64})))
│ %7 = #33::var"#33#34"{Tuple{Int64, Int64}, DataType}
│ %8 = Main.Val(4)::Core.Const(Val{4}())
│ %9 = Main.ntuple(%7, %8)::NTuple{4, Matrix{_A} where _A}
│ (mem_init = %9)
└── return %9
```
It seems the inferred `CT` wasn’t transmitted into the anonymous function.
I tried this code on 1.5.1 ,1.6.1 and Master, and the results are similar.
---
### Author:  [@N5N3](https://discourse.julialang.org/u/N5N3)
#### Post date: [April 27, 2021, 2:44am UTC](https://discourse.julialang.org/t/why-is-this-type-inference-failed/60077/2 "2021-04-27T02:44:23Z")
By the way, the following is ok
```julia
function interfer_test(obj::T, Ls::NTuple{2,<:Integer}) where {T}
CT = complex(T)
mem_init = ntuple(_ -> zeros(CT, (100,100)), Val(4))
end
@code_warntype interfer_test(1,(100,100))
```
which returns
```julia
Variables
#self#::Core.Const(interfer_test)
obj::Int64
Ls::Tuple{Int64, Int64}
#35::var"#35#36"{DataType}
mem_init::NTuple{4, Matrix{Complex{Int64}}}
CT::Type{Complex{Int64}}
Body::NTuple{4, Matrix{Complex{Int64}}}
1 ─ (CT = Main.complex($(Expr(:static_parameter, 1))))
│ %2 = Main.:(var"#35#36")::Core.Const(var"#35#36")
│ %3 = Core.typeof(CT::Core.Const(Complex{Int64}))::Core.Const(DataType)
│ %4 = Core.apply_type(%2, %3)::Core.Const(var"#35#36"{DataType})
│ (#35 = %new(%4, CT::Core.Const(Complex{Int64})))
│ %6 = #35::Core.Const(var"#35#36"{DataType}(Complex{Int64}))::Core.Const(var"#35#36"{DataType}(Complex{Int64}))
│ %7 = Main.Val(4)::Core.Const(Val{4}())
│ %8 = Main.ntuple(%6, %7)::NTuple{4, Matrix{Complex{Int64}}}
│ (mem_init = %8)
└── return %8
```