From e69ed7aa24d26b663e4b76dec13650595b9ac93e Mon Sep 17 00:00:00 2001
From: csicar <carsten.csiky@gmail.com>
Date: Sat, 4 Dec 2021 22:26:26 +0100
Subject: [PATCH 1/7] Add Mirror and Snoc type classes to Symbol

---
 src/Type/Data/Symbol.purs | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/src/Type/Data/Symbol.purs b/src/Type/Data/Symbol.purs
index 8ff8564..534406c 100644
--- a/src/Type/Data/Symbol.purs
+++ b/src/Type/Data/Symbol.purs
@@ -5,6 +5,11 @@ module Type.Data.Symbol
   , compare
   , uncons
   , class Equals
+  , class Mirror
+  , class MirrorP
+  , mirror
+  , class Snoc
+  , snoc
   , equals
   ) where
 
@@ -33,3 +38,36 @@ instance equalsSymbol
 
 equals :: forall proxy l r o. Equals l r o => proxy l -> proxy r -> Proxy o
 equals _ _ = Proxy
+
+
+-- Mirror
+
+class MirrorP (a :: Symbol) (mirror :: Symbol) | a -> mirror, mirror -> a
+
+instance mirrorEmpty :: MirrorP "" ""
+else
+instance mirrorCons :: (Cons head tail sym, MirrorP tailMirror tail, MirrorP tail tailMirror, Append tailMirror head mirror) => MirrorP sym mirror
+
+class Mirror (a :: Symbol) (mirror :: Symbol) | a -> mirror, mirror -> a
+
+instance mirrorMirrorP :: (MirrorP a b, MirrorP b a) => Mirror a b
+
+mirror :: ∀a b. Mirror a b => SProxy a -> SProxy b
+mirror _ = SProxy
+
+-- Snoc
+
+--| ```purescript
+--| Snoc "symbo" "l" ?x ~~> ?x = "symbol"
+--| Snoc ?a ?b "symbol" ~~> ?a = "symbo", ?b = "l"
+--| ```
+-- | `end` must be a single character
+class Snoc (list :: Symbol) (end :: Symbol) (symbol :: Symbol) | end list -> symbol, symbol -> end list
+
+instance snocMirror :: (Mirror sym mirror, Cons end listMirror mirror, Mirror listMirror list) => Snoc list end sym
+
+--| ```purescript
+--| snoc (SProxy :: SProxy "symbo") (SProxy :: SProxy "l") = SProxy :: SProxy "symbol"
+--| ```
+snoc :: ∀a b c. Snoc a b c => SProxy a -> SProxy b -> SProxy c
+snoc _ _ = SProxy

From a3f971420c05796055eba8bc8e42c899b6bd1004 Mon Sep 17 00:00:00 2001
From: csicar <carsten.csiky@gmail.com>
Date: Sat, 4 Dec 2021 22:30:50 +0100
Subject: [PATCH 2/7] Add tests

---
 test/Main.purs | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 test/Main.purs

diff --git a/test/Main.purs b/test/Main.purs
new file mode 100644
index 0000000..9fede0c
--- /dev/null
+++ b/test/Main.purs
@@ -0,0 +1,38 @@
+module Test.Main where
+
+import Prelude
+
+import Effect (Effect)
+import Effect.Class.Console (log)
+import Type.Data.Symbol (SProxy(..), mirror, snoc)
+
+-- mirror
+testMirror :: SProxy "lobmys"
+testMirror = mirror (SProxy::_ "symbol")
+
+testMirror1 :: SProxy _
+testMirror1 = mirror (SProxy::_ "symbol")
+
+testMirror2 :: SProxy "lobmyys"
+testMirror2 = mirror (SProxy :: SProxy _)
+
+-- snoc
+testSnoc :: SProxy "symbol"
+testSnoc = snoc (SProxy :: SProxy "symbo") (SProxy :: SProxy "l")
+
+testSnoc1 :: SProxy _
+testSnoc1 = snoc (SProxy :: SProxy "symbo") (SProxy :: SProxy "l")
+
+testSnoc2 :: SProxy "symbol"
+testSnoc2 = snoc (SProxy :: SProxy _) (SProxy :: SProxy "l")
+
+testSnoc3 :: SProxy "symbol"
+testSnoc3 = snoc (SProxy :: SProxy "symbo") (SProxy :: SProxy _)
+
+testSnoc4 :: SProxy "s"
+testSnoc4 = snoc (SProxy :: SProxy "") (SProxy :: SProxy "s")
+
+
+main :: Effect Unit
+main = do
+  log "asd"
\ No newline at end of file

From ef01738d414070dbd5c3af1d852d3c2374451d00 Mon Sep 17 00:00:00 2001
From: csicar <carsten.csiky@gmail.com>
Date: Sat, 4 Dec 2021 22:59:22 +0100
Subject: [PATCH 3/7] Remove deprecated `SProxy` uses

---
 src/Type/Data/Symbol.purs | 34 ++++++++++++++++++++--------------
 test/Main.purs            | 35 ++++++++++++++++++-----------------
 2 files changed, 38 insertions(+), 31 deletions(-)

diff --git a/src/Type/Data/Symbol.purs b/src/Type/Data/Symbol.purs
index 534406c..e489ff1 100644
--- a/src/Type/Data/Symbol.purs
+++ b/src/Type/Data/Symbol.purs
@@ -1,17 +1,18 @@
 module Type.Data.Symbol
-  ( module Prim.Symbol
-  , module Data.Symbol
-  , append
-  , compare
-  , uncons
+  ( append
   , class Equals
   , class Mirror
   , class MirrorP
-  , mirror
   , class Snoc
-  , snoc
+  , compare
   , equals
-  ) where
+  , mirror
+  , module Data.Symbol
+  , module Prim.Symbol
+  , snoc
+  , uncons
+  )
+  where
 
 import Prim.Symbol (class Append, class Compare, class Cons)
 import Data.Symbol (SProxy(..), class IsSymbol, reflectSymbol, reifySymbol)
@@ -46,14 +47,19 @@ class MirrorP (a :: Symbol) (mirror :: Symbol) | a -> mirror, mirror -> a
 
 instance mirrorEmpty :: MirrorP "" ""
 else
-instance mirrorCons :: (Cons head tail sym, MirrorP tailMirror tail, MirrorP tail tailMirror, Append tailMirror head mirror) => MirrorP sym mirror
+instance mirrorCons :: 
+  ( Cons head tail sym
+  , MirrorP tailMirror tail
+  , MirrorP tail tailMirror
+  , Append tailMirror head mirror
+  ) => MirrorP sym mirror
 
 class Mirror (a :: Symbol) (mirror :: Symbol) | a -> mirror, mirror -> a
 
 instance mirrorMirrorP :: (MirrorP a b, MirrorP b a) => Mirror a b
 
-mirror :: ∀a b. Mirror a b => SProxy a -> SProxy b
-mirror _ = SProxy
+mirror :: ∀ proxy a b. Mirror a b => proxy a -> Proxy b
+mirror _ = Proxy
 
 -- Snoc
 
@@ -67,7 +73,7 @@ class Snoc (list :: Symbol) (end :: Symbol) (symbol :: Symbol) | end list -> sym
 instance snocMirror :: (Mirror sym mirror, Cons end listMirror mirror, Mirror listMirror list) => Snoc list end sym
 
 --| ```purescript
---| snoc (SProxy :: SProxy "symbo") (SProxy :: SProxy "l") = SProxy :: SProxy "symbol"
+--| snoc (Proxy :: Proxy "symbo") (Proxy :: Proxy "l") = Proxy :: Proxy "symbol"
 --| ```
-snoc :: ∀a b c. Snoc a b c => SProxy a -> SProxy b -> SProxy c
-snoc _ _ = SProxy
+snoc :: ∀a b c. Snoc a b c => Proxy a -> Proxy b -> Proxy c
+snoc _ _ = Proxy
diff --git a/test/Main.purs b/test/Main.purs
index 9fede0c..25436ac 100644
--- a/test/Main.purs
+++ b/test/Main.purs
@@ -4,33 +4,34 @@ import Prelude
 
 import Effect (Effect)
 import Effect.Class.Console (log)
-import Type.Data.Symbol (SProxy(..), mirror, snoc)
+import Type.Data.Symbol (mirror, reifySymbol, snoc)
+import Type.Proxy (Proxy(..))
 
 -- mirror
-testMirror :: SProxy "lobmys"
-testMirror = mirror (SProxy::_ "symbol")
+testMirror :: Proxy "lobmys"
+testMirror = mirror (Proxy::_ "symbol")
 
-testMirror1 :: SProxy _
-testMirror1 = mirror (SProxy::_ "symbol")
+testMirror1 :: Proxy _
+testMirror1 = mirror (Proxy::_ "symbol")
 
-testMirror2 :: SProxy "lobmyys"
-testMirror2 = mirror (SProxy :: SProxy _)
+testMirror2 :: Proxy "lobmyys"
+testMirror2 = mirror (Proxy :: Proxy _)
 
 -- snoc
-testSnoc :: SProxy "symbol"
-testSnoc = snoc (SProxy :: SProxy "symbo") (SProxy :: SProxy "l")
+testSnoc :: Proxy "symbol"
+testSnoc = snoc (Proxy :: Proxy "symbo") (Proxy :: Proxy "l")
 
-testSnoc1 :: SProxy _
-testSnoc1 = snoc (SProxy :: SProxy "symbo") (SProxy :: SProxy "l")
+testSnoc1 :: Proxy _
+testSnoc1 = snoc (Proxy :: Proxy "symbo") (Proxy :: Proxy "l")
 
-testSnoc2 :: SProxy "symbol"
-testSnoc2 = snoc (SProxy :: SProxy _) (SProxy :: SProxy "l")
+testSnoc2 :: Proxy "symbol"
+testSnoc2 = snoc (Proxy :: Proxy _) (Proxy :: Proxy "l")
 
-testSnoc3 :: SProxy "symbol"
-testSnoc3 = snoc (SProxy :: SProxy "symbo") (SProxy :: SProxy _)
+testSnoc3 :: Proxy "symbol"
+testSnoc3 = snoc (Proxy :: Proxy "symbo") (Proxy :: Proxy _)
 
-testSnoc4 :: SProxy "s"
-testSnoc4 = snoc (SProxy :: SProxy "") (SProxy :: SProxy "s")
+testSnoc4 :: Proxy "s"
+testSnoc4 = snoc (Proxy :: Proxy "") (Proxy :: Proxy "s")
 
 
 main :: Effect Unit

From 49e94b4f519ec8ff138f6cafae8788243d1bffa7 Mon Sep 17 00:00:00 2001
From: csicar <carsten.csiky@gmail.com>
Date: Sat, 4 Dec 2021 23:24:18 +0100
Subject: [PATCH 4/7] Rename `reverse` to match convention

---
 src/Type/Data/Symbol.purs | 40 ++++++++++++++++++++++----------------
 test/Main.purs            | 41 ++++++++++++++++++++++++---------------
 2 files changed, 48 insertions(+), 33 deletions(-)

diff --git a/src/Type/Data/Symbol.purs b/src/Type/Data/Symbol.purs
index e489ff1..2af5549 100644
--- a/src/Type/Data/Symbol.purs
+++ b/src/Type/Data/Symbol.purs
@@ -1,12 +1,12 @@
 module Type.Data.Symbol
   ( append
   , class Equals
-  , class Mirror
-  , class MirrorP
+  , class Reverse
+  , class ReverseP
   , class Snoc
   , compare
   , equals
-  , mirror
+  , reverse
   , module Data.Symbol
   , module Prim.Symbol
   , snoc
@@ -41,25 +41,30 @@ equals :: forall proxy l r o. Equals l r o => proxy l -> proxy r -> Proxy o
 equals _ _ = Proxy
 
 
--- Mirror
+-- Reverse
 
-class MirrorP (a :: Symbol) (mirror :: Symbol) | a -> mirror, mirror -> a
+class ReverseP (a :: Symbol) (reversed :: Symbol) | a -> reversed, reversed -> a
 
-instance mirrorEmpty :: MirrorP "" ""
+instance reverseEmpty :: ReverseP "" ""
 else
-instance mirrorCons :: 
+instance reverseCons :: 
   ( Cons head tail sym
-  , MirrorP tailMirror tail
-  , MirrorP tail tailMirror
-  , Append tailMirror head mirror
-  ) => MirrorP sym mirror
+  , ReverseP tailReverse tail
+  , ReverseP tail tailReverse
+  , Append tailReverse head reversed
+  ) => ReverseP sym reversed
 
-class Mirror (a :: Symbol) (mirror :: Symbol) | a -> mirror, mirror -> a
+class Reverse (a :: Symbol) (reversed :: Symbol) | a -> reversed, reversed -> a
 
-instance mirrorMirrorP :: (MirrorP a b, MirrorP b a) => Mirror a b
+instance reverseReverseP :: (ReverseP a b, ReverseP b a) => Reverse a b
 
-mirror :: ∀ proxy a b. Mirror a b => proxy a -> Proxy b
-mirror _ = Proxy
+--| ```purescript
+--| > :t reverse (Proxy :: Proxy "symbol")
+--| Proxy @Symbol "lobmys"
+--| ```
+-- | 
+reverse :: ∀ proxy a b. Reverse a b => proxy a -> Proxy b
+reverse _ = Proxy
 
 -- Snoc
 
@@ -70,10 +75,11 @@ mirror _ = Proxy
 -- | `end` must be a single character
 class Snoc (list :: Symbol) (end :: Symbol) (symbol :: Symbol) | end list -> symbol, symbol -> end list
 
-instance snocMirror :: (Mirror sym mirror, Cons end listMirror mirror, Mirror listMirror list) => Snoc list end sym
+instance snocReverse :: (Reverse sym reversed, Cons end listReverse reversed, Reverse listReverse list) => Snoc list end sym
 
 --| ```purescript
---| snoc (Proxy :: Proxy "symbo") (Proxy :: Proxy "l") = Proxy :: Proxy "symbol"
+--| > :t snoc (Proxy :: Proxy "symbo") (Proxy :: Proxy "l")
+--| Proxy @Symbol "symbol"
 --| ```
 snoc :: ∀a b c. Snoc a b c => Proxy a -> Proxy b -> Proxy c
 snoc _ _ = Proxy
diff --git a/test/Main.purs b/test/Main.purs
index 25436ac..0bef914 100644
--- a/test/Main.purs
+++ b/test/Main.purs
@@ -4,35 +4,44 @@ import Prelude
 
 import Effect (Effect)
 import Effect.Class.Console (log)
-import Type.Data.Symbol (mirror, reifySymbol, snoc)
+import Prim.Symbol (class Cons)
+import Type.Data.Symbol (class Reverse, class Snoc, reifySymbol, reverse, snoc)
 import Type.Proxy (Proxy(..))
 
--- mirror
-testMirror :: Proxy "lobmys"
-testMirror = mirror (Proxy::_ "symbol")
+-- reverse
+testReverse :: Proxy "lobmys"
+testReverse = reverse (Proxy :: Proxy "symbol")
 
-testMirror1 :: Proxy _
-testMirror1 = mirror (Proxy::_ "symbol")
+testReverseForward :: Proxy _
+testReverseForward = reverse (Proxy:: Proxy "symbol")
 
-testMirror2 :: Proxy "lobmyys"
-testMirror2 = mirror (Proxy :: Proxy _)
+testReverseBackward :: Proxy "lobmyys"
+testReverseBackward = reverse (Proxy :: Proxy _)
+
+testReverseSingle :: Proxy "s"
+testReverseSingle = reverse $ Proxy :: Proxy "s"
+
+testReverseEmpty :: Proxy ""
+testReverseEmpty = reverse $ Proxy :: Proxy ""
 
 -- snoc
 testSnoc :: Proxy "symbol"
 testSnoc = snoc (Proxy :: Proxy "symbo") (Proxy :: Proxy "l")
 
-testSnoc1 :: Proxy _
-testSnoc1 = snoc (Proxy :: Proxy "symbo") (Proxy :: Proxy "l")
+testSnocForward :: Proxy _
+testSnocForward = snoc (Proxy :: Proxy "symbo") (Proxy :: Proxy "l")
 
-testSnoc2 :: Proxy "symbol"
-testSnoc2 = snoc (Proxy :: Proxy _) (Proxy :: Proxy "l")
+testSnocBackwardLeft :: Proxy "symbol"
+testSnocBackwardLeft = snoc (Proxy :: Proxy _) (Proxy :: Proxy "l")
 
-testSnoc3 :: Proxy "symbol"
-testSnoc3 = snoc (Proxy :: Proxy "symbo") (Proxy :: Proxy _)
+testSnocBackwardRight :: Proxy "symbol"
+testSnocBackwardRight = snoc (Proxy :: Proxy "symbo") (Proxy :: Proxy _)
 
-testSnoc4 :: Proxy "s"
-testSnoc4 = snoc (Proxy :: Proxy "") (Proxy :: Proxy "s")
+testSnocBackwardBoth :: Proxy "symbol"
+testSnocBackwardBoth = snoc (Proxy :: Proxy _) (Proxy :: Proxy _)
 
+testSnocEmpty :: Proxy "s"
+testSnocEmpty = snoc (Proxy :: Proxy "") (Proxy :: Proxy "s")
 
 main :: Effect Unit
 main = do

From aa2c4a2a1c82ea0f3b1481fb016b6559a5a689a3 Mon Sep 17 00:00:00 2001
From: csicar <carsten.csiky@gmail.com>
Date: Mon, 6 Dec 2021 01:06:17 +0100
Subject: [PATCH 5/7] Add suggested idem test

---
 bower.json     |  4 ++++
 test/Main.purs | 19 +++++++++++++++++--
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/bower.json b/bower.json
index 2ef2de0..ba889df 100644
--- a/bower.json
+++ b/bower.json
@@ -18,5 +18,9 @@
   "dependencies": {
     "purescript-prelude": "^5.0.0",
     "purescript-type-equality": "^4.0.0"
+  },
+  "devDependencies": {
+    "purescript-assert": "^5.0.0",
+    "purescript-console": "^5.0.0"
   }
 }
diff --git a/test/Main.purs b/test/Main.purs
index 0bef914..fdf3b71 100644
--- a/test/Main.purs
+++ b/test/Main.purs
@@ -2,10 +2,12 @@ module Test.Main where
 
 import Prelude
 
+import Debug (spy)
 import Effect (Effect)
 import Effect.Class.Console (log)
 import Prim.Symbol (class Cons)
-import Type.Data.Symbol (class Reverse, class Snoc, reifySymbol, reverse, snoc)
+import Test.Assert (assertTrue)
+import Type.Data.Symbol (class IsSymbol, class Reverse, class ReverseP, class Snoc, reflectSymbol, reverse, snoc)
 import Type.Proxy (Proxy(..))
 
 -- reverse
@@ -24,6 +26,16 @@ testReverseSingle = reverse $ Proxy :: Proxy "s"
 testReverseEmpty :: Proxy ""
 testReverseEmpty = reverse $ Proxy :: Proxy ""
 
+-- or something like this that verifies this is true
+propReverseIdem :: forall a b . IsSymbol a => IsSymbol b => Reverse a b => Reverse b a => Proxy a -> Boolean
+propReverseIdem p = reflectSymbol p == reflectSymbol sameThing
+  where
+  sameThing = reverse (reverse p :: Proxy b)
+
+-- just confirming that more complex unicode works
+testUnicode :: Proxy "🍎enip"
+testUnicode = reverse (Proxy :: Proxy "pine🍎")
+
 -- snoc
 testSnoc :: Proxy "symbol"
 testSnoc = snoc (Proxy :: Proxy "symbo") (Proxy :: Proxy "l")
@@ -45,4 +57,7 @@ testSnocEmpty = snoc (Proxy :: Proxy "") (Proxy :: Proxy "s")
 
 main :: Effect Unit
 main = do
-  log "asd"
\ No newline at end of file
+  assertTrue $ propReverseIdem (Proxy :: Proxy "Test Symbol")
+  assertTrue $ propReverseIdem (Proxy :: Proxy "Unico∀e")
+  assertTrue $ propReverseIdem (Proxy :: Proxy "<-<>")
+  assertTrue $ propReverseIdem (Proxy :: Proxy "pine🍎")
\ No newline at end of file

From 8ba140181e574180a32806eab0529607b38551a0 Mon Sep 17 00:00:00 2001
From: csicar <carsten.csiky@gmail.com>
Date: Mon, 6 Dec 2021 01:09:24 +0100
Subject: [PATCH 6/7] Update comments

---
 test/Main.purs | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/test/Main.purs b/test/Main.purs
index fdf3b71..658d6c5 100644
--- a/test/Main.purs
+++ b/test/Main.purs
@@ -26,13 +26,12 @@ testReverseSingle = reverse $ Proxy :: Proxy "s"
 testReverseEmpty :: Proxy ""
 testReverseEmpty = reverse $ Proxy :: Proxy ""
 
--- or something like this that verifies this is true
+-- Reversing a reversed Symbol should be the same as the Symbol itself
 propReverseIdem :: forall a b . IsSymbol a => IsSymbol b => Reverse a b => Reverse b a => Proxy a -> Boolean
 propReverseIdem p = reflectSymbol p == reflectSymbol sameThing
   where
   sameThing = reverse (reverse p :: Proxy b)
 
--- just confirming that more complex unicode works
 testUnicode :: Proxy "🍎enip"
 testUnicode = reverse (Proxy :: Proxy "pine🍎")
 

From 827bc31cc387cad295d96b19c8b2c530b6627138 Mon Sep 17 00:00:00 2001
From: csicar <carsten.csiky@gmail.com>
Date: Mon, 6 Dec 2021 01:24:50 +0100
Subject: [PATCH 7/7] Test single and empty string

---
 test/Main.purs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/test/Main.purs b/test/Main.purs
index 658d6c5..e61c5b4 100644
--- a/test/Main.purs
+++ b/test/Main.purs
@@ -59,4 +59,6 @@ main = do
   assertTrue $ propReverseIdem (Proxy :: Proxy "Test Symbol")
   assertTrue $ propReverseIdem (Proxy :: Proxy "Unico∀e")
   assertTrue $ propReverseIdem (Proxy :: Proxy "<-<>")
+  assertTrue $ propReverseIdem (Proxy :: Proxy "")
+  assertTrue $ propReverseIdem (Proxy :: Proxy "1")
   assertTrue $ propReverseIdem (Proxy :: Proxy "pine🍎")
\ No newline at end of file