# Method matching an array with elements of a composite type with parametric types

**URL:** https://discourse.julialang.org/t/method-matching-an-array-with-elements-of-a-composite-type-with-parametric-types/56271
**Category:** General Usage
**Tags:** parametric-types, parametric-methods
**Created:** [March 1, 2021, 5:58pm UTC](https://discourse.julialang.org/t/method-matching-an-array-with-elements-of-a-composite-type-with-parametric-types/56271 "2021-03-01T17:58:54Z")
**Posts on this page:** 1
**Showing post:** 7

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### Author: ![rdeits](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/rdeits/32/286_2.png) [@rdeits](https://discourse.julialang.org/u/rdeits)
#### Post date: [March 2, 2021, 6:08am UTC](https://discourse.julialang.org/t/method-matching-an-array-with-elements-of-a-composite-type-with-parametric-types/56271/7 "2021-03-02T06:08:12Z")

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Check out [What's with the invariant parametric types gotcha? - #3 by rdeits](https://discourse.julialang.org/t/whats-with-the-invariant-parametric-types-gotcha/55090/3) or [Why? isa([(x,1),(y,1)], Array{Tuple{Stuff,Number},1}) = false - #5 by Shuhua](https://discourse.julialang.org/t/why-isa-x-1-y-1-array-tuple-stuff-number-1-false/55777/5) or [Struggling with signatures - #2 by Henrique\_Becker](https://discourse.julialang.org/t/struggling-with-signatures/52935/2)

In particular, `Array{Factor{T}, 1}` and `Array{Factor{T, 1}, 1}` are totally different types, but they are both subtypes of `Array{<:Factor{T}, 1}`

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