From bcd49ec34f3de1e723337e828a11c33c17f5e0f5 Mon Sep 17 00:00:00 2001
From: Pevnak <pevnak@gmail.com>
Date: Sat, 28 Nov 2020 21:06:43 +0100
Subject: [PATCH 1/3] added an initial version of normalise, propname, and
 decompose

---
 src/sugar.jl | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/src/sugar.jl b/src/sugar.jl
index ca3e742d..63a71561 100644
--- a/src/sugar.jl
+++ b/src/sugar.jl
@@ -275,3 +275,61 @@ function show_composition_order(io::IO, lens::ComposedOptic)
     print(io, ")")
 end
 
+
+"""
+    decompose(optic)
+
+decomposes the `ComposedOptic` into tuple of simple properties (Lenses) 
+while preserving the order
+
+```julia 
+julia> decompose(@optic _.a.b.c.d)
+((@optic _.d), (@optic _.c), (@optic _.b), (@optic _.a))
+
+julia> decompose((@optic _.c.d) ∘ (@optic _.a.b))
+((@optic _.d), (@optic _.c), (@optic _.b), (@optic _.a))
+"""
+decompose(optic) = (optic,)
+decompose(optic::ComposedOptic) = (decompose(optic.outer)..., decompose(optic.inner)...)
+
+"""
+    propname(::PropertyLens{name})
+
+returns the name of the propery lens 
+```julia
+julia> propname(@optic _.a)
+:a
+```
+
+Using `propname` with `decompose`, list all keys of can be listed as 
+```julia
+julia> map(propname, decompose((@optic _.c.d) ∘ (@optic _.a.b))
+(:d, :c, :b, :a)
+```
+"""
+propname(::PropertyLens{name}) where {name} = name
+
+
+"""
+    normalise(optic)
+
+transforms the optic such that the `inner` lens contains always a the `PropertyLens`
+
+```julia 
+julia> optic = (@optic _.a) ∘ (@optic _.b.c)
+(@optic _.a) ∘ (@optic _.c) ∘ (@optic _.b)
+
+julia> optic.inner
+(@optic _.c) ∘ (@optic _.b)
+
+julia> optic.outer
+(@optic _.a)
+
+julia> normalise(optic).inner
+(@optic _.b)
+
+julia> normalise(optic).outer
+(@optic _.a) ∘ (@optic _.c)
+"""
+normalise(optic) = optic
+normalise(optic::ComposedOptic) = foldl(∘, decompose(optic))

From 4594d7cd6dd5bf922983649a7f7995aa0f29724a Mon Sep 17 00:00:00 2001
From: Pevnak <pevnak@gmail.com>
Date: Sat, 28 Nov 2020 21:22:33 +0100
Subject: [PATCH 2/3] added tests

---
 src/sugar.jl        | 10 +++++-----
 test/test_optics.jl | 14 ++++++++++++++
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/src/sugar.jl b/src/sugar.jl
index 63a71561..caac9346 100644
--- a/src/sugar.jl
+++ b/src/sugar.jl
@@ -316,20 +316,20 @@ propname(::PropertyLens{name}) where {name} = name
 transforms the optic such that the `inner` lens contains always a the `PropertyLens`
 
 ```julia 
-julia> optic = (@optic _.a) ∘ (@optic _.b.c)
-(@optic _.a) ∘ (@optic _.c) ∘ (@optic _.b)
+julia> optic = (@optic _.c) ∘ (@optic _.a.b)
+(@optic _.c) ∘ (@optic _.b) ∘ (@optic _.a)
 
 julia> optic.inner
-(@optic _.c) ∘ (@optic _.b)
+(@optic _.b) ∘ (@optic _.a)
 
 julia> optic.outer
 (@optic _.a)
 
 julia> normalise(optic).inner
-(@optic _.b)
+(@optic _.a)
 
 julia> normalise(optic).outer
-(@optic _.a) ∘ (@optic _.c)
+(@optic _.c) ∘ (@optic _.b)
 """
 normalise(optic) = optic
 normalise(optic::ComposedOptic) = foldl(∘, decompose(optic))
diff --git a/test/test_optics.jl b/test/test_optics.jl
index adf774ea..db79a942 100644
--- a/test/test_optics.jl
+++ b/test/test_optics.jl
@@ -45,4 +45,18 @@ end
     @inferred modify(x -> 0, arr, @optic _ |> Elements() |> If(iseven))
 end
 
+@testset "Decomposition" begin 
+    @test Accessors.decompose(@optic _.a.b.c) == ((@optic _.c), (@optic _.b), (@optic _.a))
+end
+
+@testset "Propname" begin 
+    @test Accessors.propname(@optic _.a) == :a
+end
+
+@testset "Normalisation" begin 
+    @test Accessors.normalise((@optic _.c) ∘ (@optic _.a.b)).inner == @optic _.a
+    @test Accessors.normalise((@optic _.c) ∘ (@optic _.a.b)).outer.inner == @optic _.b
+    @test Accessors.normalise((@optic _.c) ∘ (@optic _.a.b)).outer.outer == @optic _.c
+end
+
 end#module

From 60fc955f74f805e0024782a580d06c2b56306188 Mon Sep 17 00:00:00 2001
From: Pevnak <pevnak@gmail.com>
Date: Sat, 28 Nov 2020 21:24:43 +0100
Subject: [PATCH 3/3] added tests

---
 src/sugar.jl | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/sugar.jl b/src/sugar.jl
index caac9346..6709d8f2 100644
--- a/src/sugar.jl
+++ b/src/sugar.jl
@@ -288,6 +288,7 @@ julia> decompose(@optic _.a.b.c.d)
 
 julia> decompose((@optic _.c.d) ∘ (@optic _.a.b))
 ((@optic _.d), (@optic _.c), (@optic _.b), (@optic _.a))
+```
 """
 decompose(optic) = (optic,)
 decompose(optic::ComposedOptic) = (decompose(optic.outer)..., decompose(optic.inner)...)
@@ -330,6 +331,7 @@ julia> normalise(optic).inner
 
 julia> normalise(optic).outer
 (@optic _.c) ∘ (@optic _.b)
+```
 """
 normalise(optic) = optic
 normalise(optic::ComposedOptic) = foldl(∘, decompose(optic))