# Destructuring function definition?
**URL:** https://discourse.julialang.org/t/destructuring-function-definition/135824
**Category:** General Usage
**Tags:** question
**Created:** [February 25, 2026, 2:03am UTC](https://discourse.julialang.org/t/destructuring-function-definition/135824 "2026-02-25T02:03:15Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@WalterMadelim](https://discourse.julialang.org/u/WalterMadelim)
#### Post date: [February 25, 2026, 2:03am UTC](https://discourse.julialang.org/t/destructuring-function-definition/135824/1 "2026-02-25T02:03:15Z")
Can you help me understand
```julia-auto
julia> module A
f() = g()
g() = f()
end
Main.A
julia> module B
f(), g() = g(), f()
end
ERROR: UndefVarError: `g` not defined in `Main.B`
```
?
---
### Author:  [@WalterMadelim](https://discourse.julialang.org/u/WalterMadelim)
#### Post date: [February 25, 2026, 2:07am UTC](https://discourse.julialang.org/t/destructuring-function-definition/135824/2 "2026-02-25T02:07:21Z")
Oh, I see. the line inside `B` is not function definition.
```julia-auto
julia> module C
f() = rand()
end
Main.C
julia> C.f()
0.24515636911767225
julia> C.f()
0.6758273362892651
julia> module D
f(), g() = rand(), rand()
end
Main.D
julia> D.f()
0.6869168702705465
julia> D.f()
0.6869168702705465
julia> D.f
f (generic function with 1 method)
```
---
### Author:  [@heliosdrm](https://discourse.julialang.org/u/heliosdrm)
#### Post date: [February 25, 2026, 10:49am UTC](https://discourse.julialang.org/t/destructuring-function-definition/135824/3 "2026-02-25T10:49:50Z")
The problem in the original post was not related to the line in `B` being or not a function definition, but to `g` (referred to in the right hand side of that line) having been defined in a module `A` that `B` cannot “see”. In your second example, on the other hand, the right hand side of the line in `D` refers to functions that are in `Main` (`rand`), so they can be seen.
By the way, what I didn’t expect is that defining a tuple of functions does not behave as when they are defined individually: the function calls in the “definition” are evaluated right away, so `rand` is not random anymore. This can be seen more clearly if those definitions are made outside a module, directly on `Main`:
```julia
julia> f() = rand()
f (generic function with 1 method)
julia> g(), h() = rand(), rand()
(0.7979213943713473, 0.6634292395166483)
```