diff --git a/gitlab-pages/docs/advanced/entrypoints-contracts.md b/gitlab-pages/docs/advanced/entrypoints-contracts.md
index c105d08f6..29160031c 100644
--- a/gitlab-pages/docs/advanced/entrypoints-contracts.md
+++ b/gitlab-pages/docs/advanced/entrypoints-contracts.md
@@ -386,13 +386,14 @@ type return = (list (operation), storage);
 
 let dest : address = ("KT19wgxcuXG9VH4Af5Tpm1vqEKdaMFpznXT3" : address);
 
-let proxy = ((param, store): (parameter, storage)) : return =>
+let proxy = ((param, store): (parameter, storage)) : return => {
   let counter : contract (parameter) = Operation.get_contract (dest);
   (* Reuse the parameter in the subsequent
      transaction or use another one, `mock_param`. *)
   let mock_param : parameter = Increment (5n);
   let op : operation = Operation.transaction (param, 0mutez, counter);
-  ([op], store);
+  ([op], store)
+};
 ```
 
 <!--END_DOCUSAURUS_CODE_TABS-->
diff --git a/gitlab-pages/docs/advanced/timestamps-addresses.md b/gitlab-pages/docs/advanced/timestamps-addresses.md
index dd7289e81..8c20da011 100644
--- a/gitlab-pages/docs/advanced/timestamps-addresses.md
+++ b/gitlab-pages/docs/advanced/timestamps-addresses.md
@@ -101,8 +101,8 @@ let in_24_hrs : timestamp = today - one_day;
 
 ### Comparing Timestamps
 
-You can also compare timestamps using the same comparison operators as
-for numbers.
+You can compare timestamps using the same comparison operators
+applying to numbers.
 
 <!--DOCUSAURUS_CODE_TABS-->
 <!--Pascaligo-->
@@ -124,10 +124,10 @@ let not_tomorrow : bool = (Current.time == in_24_hrs);
 
 ## Addresses
 
-The type `address` in LIGO is used to denote Tezos addresses (tz1,
-tz2, tz3, KT1, ...). Currently, addresses are created by casting a
-string to the type `address`. Beware of failures if the address is
-invalid. Consider the following examples.
+The type `address` in LIGO denotes Tezos addresses (tz1, tz2, tz3,
+KT1, ...). Currently, addresses are created by casting a string to the
+type `address`. Beware of failures if the address is invalid. Consider
+the following examples.
 
 <!--DOCUSAURUS_CODE_TABS-->
 <!--Pascaligo-->
@@ -152,7 +152,7 @@ let my_account : address =
 
 ## Signatures
 
-The type `signature` in LIGO datatype is used for Tezos signature
+The `signature` type in LIGO datatype is used for Tezos signatures
 (edsig, spsig). Signatures are created by casting a string. Beware of
 failure if the signature is invalid.
 
@@ -181,7 +181,7 @@ signature);
 
 ## Keys
 
-The type `key` in LIGO is used for Tezos public keys. Do not confuse
+The `key` type in LIGO is used for Tezos public keys. Do not confuse
 them with map keys. Keys are made by casting strings. Beware of
 failure if the key is invalid.
 
diff --git a/gitlab-pages/docs/language-basics/boolean-if-else.md b/gitlab-pages/docs/language-basics/boolean-if-else.md
index b6d3b0da3..d938f5b7b 100644
--- a/gitlab-pages/docs/language-basics/boolean-if-else.md
+++ b/gitlab-pages/docs/language-basics/boolean-if-else.md
@@ -34,7 +34,10 @@ In LIGO, only values of the same type can be compared. Moreover, not
 all values of the same type can be compared, only those with
 *comparable types*, which is a concept lifted from
 Michelson. Comparable types include, for instance, `int`, `nat`,
-`string`, `tez`, `timestamp`, `address`, etc.
+`string`, `tez`, `timestamp`, `address`, etc. As an example of
+non-comparable types: maps, sets or lists are not comparable: if you
+wish to compare them, you will have to write your own comparison
+function.
 
 ### Comparing Strings
 
@@ -110,7 +113,7 @@ let h : bool = (a != b);
 ```pascaligo group=d
 const a : tez  = 5mutez
 const b : tez  = 10mutez
-const c : bool = (a = b) // false
+const c : bool = (a = b) // False
 ```
 <!--CameLIGO-->
 ```cameligo group=d
@@ -129,7 +132,7 @@ let c : bool = (a == b); // false
 
 ## Conditionals
 
-Conditional logic enables to fork the control flow depending on the
+Conditional logic enables forking the control flow depending on the
 state.
 
 <!--DOCUSAURUS_CODE_TABS-->
diff --git a/gitlab-pages/docs/language-basics/functions.md b/gitlab-pages/docs/language-basics/functions.md
index bcae8b468..c43e5e33e 100644
--- a/gitlab-pages/docs/language-basics/functions.md
+++ b/gitlab-pages/docs/language-basics/functions.md
@@ -10,11 +10,11 @@ logic into functions.
 ## Blocks
 
 In PascaLIGO, *blocks* enable the sequential composition of
-*instructions* into an isolated scope. Each `block` needs to include
-at least one instruction. If we need a placeholder *placeholder*, we
-use the instruction called `skip`, that leaves the state
-invariant. The rationale for `skip` instead of a truly empty block is
-that it prevents you from writing an empty block by mistake.
+instructions into an isolated scope. Each block needs to include at
+least one instruction. If we need a placeholder, we use the
+instruction `skip` which leaves the state unchanged.  The rationale
+for `skip` instead of a truly empty block is that it prevents you from
+writing an empty block by mistake.
 
 <!--DOCUSAURUS_CODE_TABS-->
 <!--Pascaligo-->
@@ -31,10 +31,10 @@ Blocks are more versatile than simply containing instructions:
 they can also include *declarations* of values, like so:
 ```pascaligo skip
 // terse style
-block { const a : int = 1; }
+block { const a : int = 1 }
 // verbose style
 begin
-  const a : int = 1;
+  const a : int = 1
 end
 ```
 
diff --git a/gitlab-pages/docs/language-basics/loops.md b/gitlab-pages/docs/language-basics/loops.md
index 9a5a4d47b..6ae699cd6 100644
--- a/gitlab-pages/docs/language-basics/loops.md
+++ b/gitlab-pages/docs/language-basics/loops.md
@@ -64,7 +64,7 @@ to have a special type: if the type of the accumulator is `t`, then it
 must have the type `bool * t` (not simply `t`). It is the boolean
 value that denotes whether the stopping condition has been reached.
 
-```cameligo group=b
+```cameligo group=a
 let iter (x,y : nat * nat) : bool * (nat * nat) =
   if y = 0n then false, (x,y) else true, (y, x mod y)
 
@@ -77,7 +77,7 @@ let gcd (x,y : nat * nat) : nat =
 To ease the writing and reading of the iterated functions (here,
 `iter`), two predefined functions are provided: `continue` and `stop`:
 
-```cameligo group=c
+```cameligo group=a
 let iter (x,y : nat * nat) : bool * (nat * nat) =
   if y = 0n then stop (x,y) else continue (y, x mod y)
 
@@ -113,27 +113,29 @@ accumulator is `t`, then it must have the type `bool * t` (not simply
 `t`). It is the boolean value that denotes whether the stopping
 condition has been reached.
 
-```reasonligo group=d
+```reasonligo group=a
 let iter = ((x,y) : (nat, nat)) : (bool, (nat, nat)) =>
   if (y == 0n) { (false, (x,y)); } else { (true, (y, x mod y)); };
 
-let gcd = ((x,y) : (nat, nat)) : nat =>
+let gcd = ((x,y) : (nat, nat)) : nat => {
   let (x,y) = if (x < y) { (y,x); } else { (x,y); };
   let (x,y) = Loop.fold_while (iter, (x,y));
-  x;
+  x
+};
 ```
 
 To ease the writing and reading of the iterated functions (here,
 `iter`), two predefined functions are provided: `continue` and `stop`:
 
-```reasonligo group=e
+```reasonligo group=b
 let iter = ((x,y) : (nat, nat)) : (bool, (nat, nat)) =>
   if (y == 0n) { stop ((x,y)); } else { continue ((y, x mod y)); };
 
-let gcd = ((x,y) : (nat, nat)) : nat =>
+let gcd = ((x,y) : (nat, nat)) : nat => {
   let (x,y) = if (x < y) { (y,x); } else { (x,y); };
   let (x,y) = Loop.fold_while (iter, (x,y));
-  x;
+  x
+};
 ```
 <!--END_DOCUSAURUS_CODE_TABS-->
 
@@ -147,7 +149,7 @@ To iterate over a range of integers you use a loop of the form `for
 familiar for programmers of imperative languages. Note that, for the
 sake of generality, the bounds are of type `int`, not `nat`.
 
-```pascaligo group=f
+```pascaligo group=c
 function sum (var n : nat) : int is block {
   var acc : int := 0;
   for i := 1 to int (n) block {
@@ -177,7 +179,7 @@ of the form `for <element var> in <collection type> <collection var>
 
 Here is an example where the integers in a list are summed up.
 
-```pascaligo group=g
+```pascaligo group=d
 function sum_list (var l : list (int)) : int is block {
   var total : int := 0;
   for i in list l block {
@@ -197,7 +199,7 @@ gitlab-pages/docs/language-basics/src/loops/collection.ligo sum_list
 
 Here is an example where the integers in a set are summed up.
 
-```pascaligo=g
+```pascaligo=e
 function sum_set (var s : set (int)) : int is block {
   var total : int := 0;
   for i in set s block {
diff --git a/gitlab-pages/docs/language-basics/maps-records.md b/gitlab-pages/docs/language-basics/maps-records.md
index 6a6572c37..50ec7e8b8 100644
--- a/gitlab-pages/docs/language-basics/maps-records.md
+++ b/gitlab-pages/docs/language-basics/maps-records.md
@@ -358,7 +358,7 @@ let moves : register =
 let moves : register =
   Map.literal ([
     ("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx" : address, (1,2)),
-    ("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" : address, (0,3)),]);
+    ("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" : address, (0,3))]);
 ```
 
 > The `Map.literal` predefined function builds a map from a list of
@@ -377,8 +377,8 @@ example:
 <!--DOCUSAURUS_CODE_TABS-->
 <!--Pascaligo-->
 ```pascaligo group=f
-(*const my_balance : option (move) =
-  moves [("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" : address)] *)
+const my_balance : option (move) =
+  moves [("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" : address)]
 ```
 
 <!--Cameligo-->
@@ -418,11 +418,12 @@ let force_access (key, moves : address * register) : move =
 ```
 
 <!--Reasonligo-->
-```reasonlig group=f
-let force_access : ((key, moves) : address * register) : move => {
-  switch (Map.find_opt key moves) with
-    Some move -> move
-  | None -> (failwith "No move." : move)
+```reasonligo group=f
+let force_access = ((key, moves) : (address, register)) : move => {
+  switch (Map.find_opt (key, moves)) {
+  | Some (move) => move
+  | None => failwith ("No move.") : move
+  }
 };
 ```
 <!--END_DOCUSAURUS_CODE_TABS-->
@@ -475,9 +476,8 @@ let assign (m : register) : register =
 ```
 
 > Notice the optional value `Some (4,9)` instead of `(4,9)`. If we had
-> use `None` instead, that would have meant that the binding is only
-> defined on its key, but not its value. This encoding enables
-> partially defined bindings.
+> use `None` instead, that would have meant that the binding is
+> removed.
 
 <!--Reasonligo-->
 
@@ -492,9 +492,8 @@ let assign = (m : register) : register => {
 ```
 
 > Notice the optional value `Some (4,9)` instead of `(4,9)`. If we had
-> use `None` instead, that would have meant that the binding is only
-> defined on its key, but not its value. This encoding enables
-> partially defined bindings.
+> use `None` instead, that would have meant that the binding is
+> removed.
 
 <!--END_DOCUSAURUS_CODE_TABS-->
 
@@ -601,7 +600,7 @@ let map_op = (m : register) : register => {
 A *fold operation* is the most general of iterations. The iterated
 function takes two arguments: an *accumulator* and the structure
 *element* at hand, with which it then produces a new accumulator. This
-enables to have a partial result that becomes complete when the
+enables having a partial result that becomes complete when the
 traversal of the data structure is over.
 
 <!--DOCUSAURUS_CODE_TABS-->
@@ -622,7 +621,7 @@ let fold_op (m : register) : register =
 
 <!--Reasonligo-->
 ```reasonligo group=f
-let fold_op = (m: register): register => {
+let fold_op = (m : register) : register => {
   let aggregate = ((i,j): (int, (address, move))) => i + j[1][1];
   Map.fold (aggregate, m, 5);
 };
@@ -703,7 +702,7 @@ let moves : register =
 let moves : register =
   Big_map.literal ([
     ("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx" : address, (1,2)),
-    ("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" : address, (0,3)),]);
+    ("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" : address, (0,3))]);
 ```
 
 > The predefind function `Big_map.literal` constructs a big map from a
diff --git a/gitlab-pages/docs/language-basics/math-numbers-tez.md b/gitlab-pages/docs/language-basics/math-numbers-tez.md
index 859c73097..bb274cd7c 100644
--- a/gitlab-pages/docs/language-basics/math-numbers-tez.md
+++ b/gitlab-pages/docs/language-basics/math-numbers-tez.md
@@ -8,15 +8,14 @@ LIGO offers three built-in numerical types: `int`, `nat` and `tez`.
 ## Addition
 
 Addition in LIGO is accomplished by means of the `+` infix
-operator. Some type constraints apply, for example you ca not add a
+operator. Some type constraints apply, for example you cannot add a
 value of type `tez` to a value of type `nat`.
 
 In the following example you can find a series of arithmetic
 operations, including various numerical types. However, some bits
-remain in comments because they would otherwise not compile because,
-for example, adding a value of type `int` to a value of type `tez` is
-invalid. Note that adding an integer to a natural number produces an
-integer.
+remain in comments as they would otherwise not compile, for example,
+adding a value of type `int` to a value of type `tez` is invalid. Note
+that adding an integer to a natural number produces an integer.
 
 <!--DOCUSAURUS_CODE_TABS-->
 <!--Pascaligo-->
@@ -115,7 +114,7 @@ let g : int = 1_000_000;
 
 ## Subtraction
 
-Subtraction looks like as follows.
+Subtraction looks as follows.
 
 > ⚠️ Even when subtracting two `nats`, the result is an `int`
 
diff --git a/gitlab-pages/docs/language-basics/src/unit-option-pattern-matching/flip.mligo b/gitlab-pages/docs/language-basics/src/unit-option-pattern-matching/flip.mligo
new file mode 100644
index 000000000..43e09b016
--- /dev/null
+++ b/gitlab-pages/docs/language-basics/src/unit-option-pattern-matching/flip.mligo
@@ -0,0 +1,6 @@
+type coin = Head | Tail
+
+let flip (c : coin) : coin =
+  match c with
+    Head -> Tail
+  | Tail -> Head
diff --git a/gitlab-pages/docs/language-basics/src/unit-option-pattern-matching/flip.religo b/gitlab-pages/docs/language-basics/src/unit-option-pattern-matching/flip.religo
new file mode 100644
index 000000000..94d496c48
--- /dev/null
+++ b/gitlab-pages/docs/language-basics/src/unit-option-pattern-matching/flip.religo
@@ -0,0 +1,7 @@
+type coin = | Head | Tail;
+
+let flip = (c : coin) : coin =>
+  switch (c) {
+  | Head => Tail
+  | Tail => Head
+  };