Define g ⨟ f = f ∘ g

base/exports.jl

@@ -193,6 +193,7 @@ export
     :,
     =>,
     ∘,
+    ⨟,
 
 # scalar math
     @evalpoly,

base/operators.jl

@@ -833,6 +833,7 @@ entered in the Julia REPL (and most editors, appropriately configured) by typing
 Function composition also works in prefix form: `∘(f, g)` is the same as `f ∘ g`.
 The prefix form supports composition of multiple functions: `∘(f, g, h) = f ∘ g ∘ h`
 and splatting `∘(fs...)` for composing an iterable collection of functions.
+See also [`⨟`](@ref) for composition in the reversed order.
 
 !!! compat "Julia 1.4"
     Multiple function composition requires at least Julia 1.4.
@@ -864,6 +865,24 @@ function ∘ end
 ∘(f, g) = (x...)->f(g(x...))
 ∘(f, g, h...) = ∘(f ∘ g, h...)
 
+"""
+    g ⨟ f
+
+Compose functions in the "opposite order": i.e. `(g ⨟ f)(args...)` means `f(g(args...))`.
+Composition `g ⨟ f` is defined as [`f ∘ g`](@ref ∘).
+
+!!! compat "Julia 1.5"
+    Opposite composition `⨟` requires at least Julia 1.5.
+
+# Examples
+```jldoctest
+julia> 1 |> (x -> 2x) ⨟ string
+"2"
+```
+"""
+function ⨟ end
+⨟(fs...) = ∘(reverse(fs)...)
+
 """
     !f::Function
 

doc/src/base/base.md

@@ -233,6 +233,7 @@ Base.invokelatest
 new
 Base.:(|>)
 Base.:(∘)
+Base.:(⨟)
 ```
 
 ## Syntax

test/operators.jl

@@ -133,6 +133,11 @@ Base.promote_rule(::Type{T19714}, ::Type{Int}) = T19714
     @test ∘(FreeMagma(1), FreeMagma(2)) === FreeMagma((1,2))
     @test ∘(FreeMagma(1), FreeMagma(2), FreeMagma(3)) === FreeMagma(((1,2), 3))
     @test ∘(FreeMagma(1), FreeMagma(2), FreeMagma(3), FreeMagma(4)) === FreeMagma((((1,2), 3), 4))
+
+    @test ⨟(FreeMagma(1)) === FreeMagma(1)
+    @test ⨟(FreeMagma(1), FreeMagma(2)) === FreeMagma((2,1))
+    @test ⨟(FreeMagma(1), FreeMagma(2), FreeMagma(3)) === FreeMagma(((3,2), 1))
+    @test ⨟(FreeMagma(1), FreeMagma(2), FreeMagma(3), FreeMagma(4)) === FreeMagma((((4,3), 2), 1))
 end
 
 @testset "function negation" begin