Merge branch 'feature/LIGO-258-update-docs' into 'dev'

LIGO-258 Docs updates

Closes LIGO-258

See merge request ligolang/ligo!272

gitlab-pages/docs/advanced/entrypoints-contracts.md

@@ -220,7 +220,7 @@ In our case, we have a `counter.ligo` contract that accepts a parameter of type
 
 <!--DOCUSAURUS_CODE_TABS-->
 <!--Pascaligo-->
-```pascaligo
+```pascaligo skip
 // counter.ligo
 type action is
 | Increment of int

gitlab-pages/docs/language-basics/boolean-if-else.md

@@ -139,21 +139,8 @@ Conditional logic is an important part of every real world program.
 ```pascaligo group=e
 const min_age: nat = 16n;
 
-(*
-    This function is really obnoxious, but it showcases
-    how the if statement and it's syntax can be used.
-
-    Normally, you'd use `with (age > min_age)` instead.
-*)
 function is_adult(const age: nat): bool is
-    block {
+    if (age > min_age) then True else False
-        var is_adult: bool := False;
-        if (age > min_age) then begin
-            is_adult := True;
-        end else begin
-            is_adult := False;
-        end
-    } with is_adult
 ```
 
 > You can run the function above with

gitlab-pages/docs/language-basics/math-numbers-tez.md

@@ -200,6 +200,18 @@ const a: int = int(1n);
 const b: nat = abs(1);
 ```
 
+<!--END_DOCUSAURUS_CODE_TABS-->
+
+## Check if a value is a `nat`
+
+You can check if a value is a `nat`, by using a syntax specific built-in function, which accepts an `int` and returns an `option(nat)`, more specifically `Some(nat)` if the provided integer is a natural number, and `None` otherwise:
+
+<!--DOCUSAURUS_CODE_TABS-->
+<!--Pascaligo-->
+```pascaligo
+const its_a_nat: option(nat) = is_nat(1)
+```
+
 <!--ReasonLIGO-->
 ```reasonligo group=e
 let a: int = int(1n);

gitlab-pages/docs/language-basics/src/boolean-if-else/if-else.ligo

@@ -0,0 +1,4 @@
+const min_age: nat = 16n;
+
+function is_adult(const age: nat): bool is
+    if (age > min_age) then True else False

gitlab-pages/docs/language-basics/src/math-numbers-tez/isnat.ligo

@@ -0,0 +1 @@
+const its_a_nat: option(nat) = is_nat(1)

gitlab-pages/docs/language-basics/src/types/annotation.ligo

@@ -0,0 +1,4 @@
+type int_map is map(int, int);
+function get_first(const int_map: int_map): option(int) is int_map[1]
+// empty map needs a type annotation
+const first: option(int) = get_first(((map end) : int_map ));

gitlab-pages/docs/language-basics/types.md

@@ -36,6 +36,8 @@ let dog_breed: animal_breed = "Saluki";
 
 <!--END_DOCUSAURUS_CODE_TABS-->
 
+> Types in LIGO are `structural`, which means that `animalBreed`/`animal_breed` and `string` are interchangable and are considered equal.
+
 ## Simple types
 <!--DOCUSAURUS_CODE_TABS-->
 <!--Pascaligo-->
@@ -146,3 +148,18 @@ let ledger: account_balances =
 ```
 
 <!--END_DOCUSAURUS_CODE_TABS-->
+
+## Annotations
+
+In certain cases, type of an expression cannot be properly determined. This can be circumvented by annotating an expression with it's desired type, here's an example:
+
+<!--DOCUSAURUS_CODE_TABS-->
+<!--Pascaligo-->
+```pascaligo
+type int_map is map(int, int);
+function get_first(const int_map: int_map): option(int) is int_map[1]
+// empty map needs a type annotation
+const first: option(int) = get_first(((map end) : int_map ));
+```
+
+<!--END_DOCUSAURUS_CODE_TABS-->

gitlab-pages/website/package-lock.json

@@ -5624,15 +5624,6 @@
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@@ -7412,15 +7403,6 @@
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       "dev": true
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-      "version": "3.1.0",
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-      "integrity": "sha1-pE5c3Vu7WlTwrSiaru2AmV19k4o=",
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-      }
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@@ -7750,6 +7732,12 @@
         "picomatch": "^2.0.4"
       }
     },
+    "reason-highlightjs": {
+      "version": "0.2.1",
+      "resolved": "https://registry.npmjs.org/reason-highlightjs/-/reason-highlightjs-0.2.1.tgz",
+      "integrity": "sha512-DWWPtfeQjwKgHj2OOieEIAB544uAVjwOAIAg2Yu09CobdUe41Yah0Z67GEvmVtpYCGG/+3CZvDRM1hMVr1zN3A==",
+      "dev": true
+    },
     "rechoir": {
       "version": "0.6.2",
       "resolved": "https://registry.npmjs.org/rechoir/-/rechoir-0.6.2.tgz",
@@ -9433,12 +9421,6 @@
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-      "integrity": "sha1-FNhGHgvdOCJL/uUDmgiY/EL80zY=",
-      "dev": true
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