Merge docs for 'Carpet Mod 1.4.29 for Minecraft 1.16.5 and Minecraft 21w10a'

docs/scarpet/Full.md

@@ -296,8 +296,8 @@ For more information, see: [EvalEx GitHub repository](https://github.com/uklimas
 `scarpet` provides a number of constants that can be used literally in scripts
 
 *   `null`: nothing, zilch, not even false
-*   `true`: pure true, or just 1 (one)
+*   `true`: pure true, can act as `1`
-*   `false`: false truth, or true falsth, 0 (zero) actually
+*   `false`: false truth, or true falsth, equals to `0`
 *   `pi`: for the fans of perimeters, its a perimeter of an apple pi of diameter 1\. About 3.14
 *   `euler`: clever guy. Derivative of its exponent is goto 1\. About 2.72
 
@@ -343,7 +343,7 @@ in [User Defined Functions and Program Control Flow](docs/scarpet/language/Funct
 1357-5 => 1352
 1357-'5' => 137
 3*'foo'-'o' => 'fff'
-l(1,3,5)+7 => l(8,10,12)
+[1,3,5]+7 => [8,10,12]
 </pre>
 
 As you can see, values can behave differently when mixed with other types in the same expression. 
@@ -403,8 +403,8 @@ In Minecraft API portion `entity ~ feature` is a shortcode for `query(entity,fea
 any extra arguments.
 
 <pre>
-l(1,2,3) ~ 2  => 1
+[1,2,3] ~ 2  => 1
-l(1,2,3) ~ 4  => null
+[1,2,3] ~ 4  => null
 
 'foobar' ~ 'baz'  => null
 'foobar' ~ '.b'  => 'ob'
@@ -430,10 +430,10 @@ Or an example to find if a player has specific enchantment on a held axe (either
 
 <pre>
 global_get_enchantment(p, ench) -> (
-$   for(l('main','offhand'),
+$   for(['main','offhand'],
 $      holds = query(p, 'holds', _);
 $      if( holds,
-$         l(what, count, nbt) = holds;
+$         [what, count, nbt] = holds;
 $         if( what ~ '_axe' && nbt ~ ench,
 $            lvl = max(lvl, number(nbt ~ '(?<=lvl:)\\d') )
 $         )
@@ -470,8 +470,8 @@ Examples:
 'foo'*3 => 'foofoofoo'
 'foofoofoo' / 3 => 'foo'
 'foofoofoo'-'o' => 'fff'
-l(1,2,3)+1  => l(2,3,4)
+[1,2,3]+1  => [2,3,4]
-b = l(100,63,100); b+l(10,0,10)  => l(110,63,110)
+b = [100,63,100]; b+[10,0,10]  => [110,63,110]
 {'a' -> 1} + {'b' -> 2} => {'a' -> 1, 'b' -> 2}
 </pre>
 
@@ -513,11 +513,12 @@ second operand is not necessary, it won't be evaluated, which means one can use
 case of success returns first positive operand (`||`) or last one (`&&`).
 
 <pre>
-true || false  => 1
+true || false  => true
-null || false => 0
+null || false => false
-null != false || run('kill gnembon')  => 1 // gnembon survives
+false || null => null
-null != false && run('kill gnembon')  => 0 // when cheats not allowed
+null != false || run('kill gnembon')  // gnembon survives
-null != false && run('kill gnembon')  => 1 // gnembon dies, cheats allowed
+null != false && run('kill gnembon')  // when cheats not allowed
+null != false && run('kill gnembon')  // gnembon dies, cheats allowed
 </pre>
 
 ### `Assignment Operators = <> +=`
@@ -531,11 +532,11 @@ require rewriting of the array anyways.
 
 <pre>
 a = 5  => a == 5
-l(a,b,c) = l(3,4,5) => a==3, b==4, c==5
+[a,b,c] = [3,4,5] => a==3, b==4, c==5
-l(minx,maxx) = sort(xi,xj);  // minx assumes min(xi, xj) and maxx, max(xi, xj)
+[minx,maxx] = sort(xi,xj);  // minx assumes min(xi, xj) and maxx, max(xi, xj)
-l(a,b,c,d,e,f) = l(range(6)); l(a,b,c) <> l(d,e,f); l(a,b,c,d,e,f)  => [3,4,5,0,1,2]
+[a,b,c,d,e,f] = [range(6)]; [a,b,c] <> [d,e,f]; [a,b,c,d,e,f]  => [3,4,5,0,1,2]
-a = l(1,2,3); a += 4  => [1,2,3,4]
+a = [1,2,3]; a += 4  => [1,2,3,4]
-a = l(1,2,3,4); a = filter(a,_!=2)  => [1,3,4]
+a = [1,2,3,4]; a = filter(a,_!=2)  => [1,3,4]
 </pre>
 
 ### `Unary Operators - +`
@@ -553,12 +554,12 @@ Require a number, flips the sign. One way to assert it's a number is by crashing
 flips boolean condition of the expression. Equivalent of `bool(expr)==false`
 
 <pre>
-!true  => 0
+!true  => false
-!false  => 1
+!false  => true
-!null  => 1
+!null  => true
-!5  => 0
+!5  => false
-!l() => 1
+!l() => true
-!l(null) => 0
+!l(null) => false
 </pre>
 # Arithmetic operations
 
@@ -696,30 +697,31 @@ as well as minecraft related concepts like `block`, `entity`, `nbt`, `text`.
 
 ### `bool(expr)`
 
-Returns a boolean context of the expression. Note that there are no true/false values in scarpet. `true` is 
+Returns a boolean context of the expression. 
-alias of 1, and `false` is 0\. Bool is also interpreting string values as boolean, which is different from other 
+Bool is also interpreting string values as boolean, which is different from other 
 places where boolean context can be used. This can be used in places where API functions return string values to 
-represent binary values
+represent binary values.
 
 <pre>
-bool(pi) => 1
+bool(pi) => true
-bool(false) => 0
+bool(false) => false
-bool('') => 0
+bool('') => false
-bool(l()) => 0
+bool(l()) => false
-bool(l('')) => 1
+bool(l('')) => true
-bool('foo') => 1
+bool('foo') => true
-bool('false') => 0
+bool('false') => false
-bool('nulL') => 0
+bool('nulL') => false
-if('false',1,0) => 1
+if('false',1,0) => true
 </pre>
 
 ### `number(expr)`
 
-Returns a numeric context of the expression. Can be used to read numbers from strings
+Returns a numeric context of the expression. Can be used to read numbers from strings, or other types
 
 <pre>
-number(null) => null
+number(null) => 0
 number(false) => 0
+number(true) => 1
 number('') => null
 number('3.14') => 3.14
 number(l()) => 0
@@ -747,15 +749,15 @@ Supported types (with `"%<?>"` syntax):
 *   `%%`: '%' character
 
 <pre>
-str(null) => null
+str(null) => 'null'
-str(false) => 0
+str(false) => 'false'
-str('') => null
+str('') => ''
-str('3.14') => 3.14
+str('3.14') => '3.14'
-str(l()) => 0
+str([]) => '[]'
-str(l('')) => 1
+str(['']) => '[]'
-str('foo') => null
+str('foo') => 'foo'
-str('3bar') => null
+str('3bar') => '3bar'
-str(2)+str(2) => 22
+str(2)+str(2) => '22'
 str('pi: %.2f',pi) => 'pi: 3.14'
 str('player at: %d %d %d',pos(player())) => 'player at: 567, -2423, 124'
 </pre>
@@ -916,7 +918,7 @@ same random object. Scarpet keeps track of up to 1024 custom random number gener
 
 <pre>
 map(range(10), floor(rand(10))) => [5, 8, 0, 6, 9, 3, 9, 9, 1, 8]
-map(range(10), bool(rand(2))) => [1, 1, 1, 0, 0, 1, 1, 0, 0, 0]
+map(range(10), bool(rand(2))) => [false, false, true, false, false, false, true, false, true, false]
 map(range(10), str('%.1f',rand(_))) => [0.0, 0.4, 0.6, 1.9, 2.8, 3.8, 5.3, 2.2, 1.6, 5.6]
 </pre>
 
@@ -1217,12 +1219,12 @@ to `all(list,expr) <=> for(list,expr)==length(list)`. `expr` also receives bound
 and `continue` have no sense and cannot be used inside of `expr` body.
 
 <pre>
-all([1,2,3], check_prime(_))  => 1
+all([1,2,3], check_prime(_))  => true
-all(neighbours(x,y,z), _=='stone')  => 1 // if all neighbours of [x, y, z] are stone
+all(neighbours(x,y,z), _=='stone')  => true // if all neighbours of [x, y, z] are stone
-map(filter(rect(0,4,0,1000,0,1000), l(x,y,z)=pos(_); all(rect(x,y,z,1,0,1),_=='bedrock') ), pos(_) )
+map(filter(rect(0,4,0,1000,0,1000), [x,y,z]=pos(_); all(rect(x,y,z,1,0,1),_=='bedrock') ), pos(_) )
   => [[-298, 4, -703], [-287, 4, -156], [-269, 4, 104], [242, 4, 250], [-159, 4, 335], [-208, 4, 416], [-510, 4, 546], [376, 4, 806]]
     // find all 3x3 bedrock structures in the top bedrock layer
-map( filter( rect(0,4,0,1000,1,1000,1000,0,1000), l(x,y,z)=pos(_);
+map( filter( rect(0,4,0,1000,1,1000,1000,0,1000), [x,y,z]=pos(_);
         all(rect(x,y,z,1,0,1),_=='bedrock') && for(rect(x,y-1,z,1,1,1,1,0,1),_=='bedrock')<8),
    pos(_) )  => [[343, 3, -642], [153, 3, -285], [674, 3, 167], [-710, 3, 398]]
     // ditto, but requiring at most 7 bedrock block in the 18 blocks below them
@@ -1475,15 +1477,73 @@ returns everywhere, but it would often lead to a messy code.
 
 It terminates entire program passing `expr` as the result of the program execution, or null if omitted.
 
-### `try(expr, catch_expr(_)?) ... throw(value?)`
+### `try(expr)` `try(expr, user_catch_expr)` `try(expr, type, catch_expr, type?, catch_expr?, ...)`
 
-`try` function evaluates expression, and continues further unless `throw` function is called anywhere 
+`try` evaluates expression, allowing capturing exceptions that would be thrown inside `expr` statement. The exceptions can be
-inside `expr`. In that case the `catch_expr` is evaluates with `_` set to the argument `throw` was called with. 
+thrown explicitly using `throw()` or internally by scarpet where code is correct but detects illegal state. The 2-argument form
-This mechanic accepts skipping thrown value - it throws null instead, and catch expression - then try returns 
+catches only user-thrown exceptions and one argument call `try(expr)` is equivalent to `try(expr, null)`, 
-null as well This mechanism allows to terminate large portion of a convoluted call stack and continue program 
+or `try(expr, 'user_exception', null)`. If multiple `type-catch` pairs are defined, the execution terminates on the first 
-execution. There is only one level of exceptions currently in carpet, so if the inner function also defines 
+applicable type for the exception thrown. Therefore, even if the caught exception matches multiple filters, only 
-the `try` catchment area, it will received the exception first, but it can technically rethrow the value its 
+the first matching block will be executed.
-getting for the outer scope. Unhandled throw acts like an exit statement.
+
+Catch expressions are evaluated with 
+`_` set to the value associated with the exception and `_trace` set to contain details about point of error (token, and line and 
+column positions), call stack and local
+variables at the time of failure. The `type` will catch any exception of that type and any subtype of this type.
+  
+
+You can use `try` mechanism to exit from large portion of a convoluted call stack and continue program execution, although catching
+exceptions is typically much more expensive comparing to not throwing them.
+
+The `try` function allows you to catch some scarpet exceptions for cases covering invalid data, like invalid
+blocks, biomes, dimensions and other things, that may have been modified by datapacks, resourcepacks or other mods,
+or when an error is outside of the programmers scope, such as problems when reading or decoding files.
+
+This is the hierarchy of the exceptions that could be thrown/caught in the with the `try` function:
+- `exception`: This is the base exception. Catching `'exception'` allows to catch everything that can be caught, 
+but like everywhere else, doing that sounds like a bad idea.
+  - `value_exception`: This is the parent for any exception that occurs due to an 
+  incorrect argument value provided to a built-in function
+    - `unknown_item`, `unknown_block`, `unknown_biome`, `unknown_sound`, `unknown_particle`, 
+    `unknown_poi_type`, `unknown_dimension`, `unknown_structure`, `unknown_criterion`: Specific 
+    errors thrown when a specified internal name does not exist or is invalid.
+  - `io_exception`: This is the parent for any exception that occurs due to an error handling external data.
+    - `nbt_read_error`: Incorrect input NBT file.
+    - `json_read_error`: Incorrect input JSON data.
+  - `user_exception`: Exception thrown by default with `throw` function.
+  
+Synopsis:
+<pre>
+inner_call() ->
+(
+   aaa = 'booyah';
+   try(
+      for (range(10), item_tags('stick'+_*'k'));
+   ,
+      print(_trace) // not caught, only catching user_exceptions
+   )
+);
+
+outer_call() -> 
+( 
+   try(
+      inner_call()
+   , 'exception', // catching everything
+      print(_trace)
+   ) 
+);
+</pre>
+Producing:
+```
+{stack: [[<app>, inner_call, 1, 14]], locals: {_a: 0, aaa: booyah, _: 1, _y: 0, _i: 1, _x: 0, _z: 0}, token: [item_tags, 5, 23]}
+```
+
+### `throw(value?)`, `throw(type, value)`, `throw(subtype, type, value)`
+
+Throws an exception that can be caught in a `try` block (see above). If ran without arguments, it will throw a `user_exception` 
+passing `null` as the value to the `catch_expr`. With two arguments you can mimic any other exception type thrown in scarpet.
+With 3 arguments, you can specify a custom exception acting as a `subtype` of a provided `type`, allowing to customize `try` 
+statements with custom exceptions.
 
 ### `if(cond, expr, cond?, expr?, ..., default?)`
 
@@ -1518,12 +1578,12 @@ In case to simplify the access with nested objects, you can add chain of address
 than calling it multiple times. `get(get(foo,a),b)` is equivalent to `get(foo, a, b)`, or `foo:a:b`.
 
 <pre>
-get(l(range(10)), 5)  => 5
+get([range(10)], 5)  => 5
-get(l(range(10)), -1)  => 9
+get([range(10)], -1)  => 9
-get(l(range(10)), 10)  => 0
+get([range(10)], 10)  => 0
-l(range(10)):93  => 3
+[range(10)]:93  => 3
 get(player() ~ 'nbt', 'Health') => 20 // inefficient way to get player health, use player() ~ 'health' instead
-get(m( l('foo',2), l('bar',3), l('baz',4) ), 'bar')  => 3
+get({ 'foo' -> 2, 'bar' -> 3, 'baz' -> 4 }, 'bar')  => 3
 </pre>
 
 ### `has(container, address, ...), has(lvalue)`
@@ -1595,13 +1655,13 @@ of the existing elements. Use `replace` to remove and replace existing element.
 and merges keys from `value` with the compound tag under the path
 
 <pre>
-a = l(1, 2, 3); put(a, 1, 4); a  => [1, 4, 3]
+a = [1, 2, 3]; put(a, 1, 4); a  => [1, 4, 3]
-a = l(1, 2, 3); put(a, null, 4); a  => [1, 2, 3, 4]
+a = [1, 2, 3]; put(a, null, 4); a  => [1, 2, 3, 4]
-a = l(1, 2, 3); put(a, 1, 4, 'insert'); a  => [1, 4, 2, 3]
+a = [1, 2, 3]; put(a, 1, 4, 'insert'); a  => [1, 4, 2, 3]
-a = l(1, 2, 3); put(a, null, l(4, 5, 6), 'extend'); a  => [1, 2, 3, 4, 5, 6]
+a = [1, 2, 3]; put(a, null, [4, 5, 6], 'extend'); a  => [1, 2, 3, 4, 5, 6]
-a = l(1, 2, 3); put(a, 1, l(4, 5, 6), 'extend'); a  => [1, 4, 5, 6, 2, 3]
+a = [1, 2, 3]; put(a, 1, [4, 5, 6], 'extend'); a  => [1, 4, 5, 6, 2, 3]
-a = l(l(0,0,0),l(0,0,0),l(0,0,0)); put(a.1, 1, 1); a  => [[0, 0, 0], [0, 1, 0], [0, 0, 0]]
+a = [[0,0,0],[0,0,0],[0,0,0]]; put(a:1, 1, 1); a  => [[0, 0, 0], [0, 1, 0], [0, 0, 0]]
-a = m(1,2,3,4); put(a, 5, null); a  => {1: null, 2: null, 3: null, 4: null, 5: null}
+a = {1,2,3,4}; put(a, 5, null); a  => {1: null, 2: null, 3: null, 4: null, 5: null}
 tag = nbt('{}'); put(tag, 'BlockData.Properties', '[1,2,3,4]'); tag  => {BlockData:{Properties:[1,2,3,4]}}
 tag = nbt('{a:[{lvl:3},{lvl:5},{lvl:2}]}'); put(tag, 'a[].lvl', 1); tag  => {a:[{lvl:1},{lvl:1},{lvl:1}]}
 tag = nbt('{a:[{lvl:[1,2,3]},{lvl:[3,2,1]},{lvl:[4,5,6]}]}'); put(tag, 'a[].lvl', 1, 2); tag
@@ -1682,10 +1742,10 @@ other parts. In that case consecutive calls to `slice` will refer to index `0` t
 cannot go back nor track where they are in the sequence (see examples).
 
 <pre>
-slice([0,1,2,3,4,5], 1, 3)  => [1, 2, 3]
+slice([0,1,2,3,4,5], 1, 3)  => [1, 2]
 slice('foobar', 0, 1)  => 'f'
 slice('foobar', 3)  => 'bar'
-slice(range(10), 3, 5)  => [3, 4, 5]
+slice(range(10), 3, 5)  => [3, 4]
 slice(range(10), 5)  => [5, 6, 7, 8, 9]
 r = range(100); [slice(r, 5, 7), slice(r, 1, 3)]  => [[5, 6], [8, 9]]
 </pre>
@@ -1720,7 +1780,7 @@ Primarily to be used in higher order functions
 
 <pre>
 range(10)  => [...]
-l(range(10))  => [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
+[range(10)]  => [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
 map(range(10),_*_)  => [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
 reduce(range(10),_a+_, 0)  => 45
 range(5,10)  => [5, 6, 7, 8, 9]
@@ -2077,6 +2137,8 @@ when it was used. Block values passed in various places like `scan` functions, e
 its properties are needed. This means that if the block at the location changes before its queried in the program this 
 might result in getting the later state, which might not be desired. Consider the following example:
 
+Throws `unknown_block` if provided input is not valid.
+
 <pre>set(10,10,10,'stone');
 scan(10,10,10,0,0,0, b = _);
 set(10,10,10,'air');
@@ -2106,6 +2168,8 @@ properties that the original source block may have contained.
 
 The returned value is either the block state that has been set, or `false` if block setting was skipped, or failed
 
+Throws `unknown_block` if provided block to set is not valid
+
 <pre>
 set(0,5,0,'bedrock')  => bedrock
 set(l(0,5,0), 'bedrock')  => bedrock
@@ -2184,6 +2248,8 @@ but doesn't open chests / containers, so have no effect on interactive blocks, l
 Returns true if placement/use was 
 successful, false otherwise.
 
+Throws `unknown_item` if `item` doesn't exist
+
 <pre>
 place_item('stone',x,y,z) // places a stone block on x,y,z block
 place_item('piston,x,y,z,'down') // places a piston facing down
@@ -2202,6 +2268,8 @@ If type is `null`, POI at position is removed. In any case, previous POI is also
 Interestingly, `unemployed`, and `nitwit` are not used in the game, meaning, they could be used as permanent spatial 
 markers for scarpet apps. `meeting` is the only one with increased max occupancy of 32.
 
+Throws `unknown_poi` if the provided point of interest doesn't exist 
+
 ### `set_biome(pos, biome_name, update=true)`
 
 Changes the biome at that block position. if update is specified and false, then chunk will not be refreshed
@@ -2212,6 +2280,8 @@ is only effective if you set it at y=0, and affects the entire column of. In the
 specific Y coordinate of the biome you want to change, and it affects roughly 4x4x4 area (give or take some random
 noise).
 
+Throws `unknown_biome` if the `biome_name` doesn't exist.
+
 ### `update(pos)`
 
 Causes a block update at position.
@@ -2236,6 +2306,8 @@ In item context, `true` means that breaking item has no nbt to use, `null` indic
 considered broken in process, and `nbt` type value, for a resulting NBT tag on a hypothetical tool. Its up to the 
 programmer to use that nbt to apply it where it belong
 
+Throws `unknown_item` if `tool` doesn't exist.
+
 Here is a sample code that can be used to mine blocks using items in player inventory, without using player context 
 for mining. Obviously, in this case the use of `harvest` would be much more applicable:
 
@@ -2327,6 +2399,8 @@ back in state definition in various applications where block properties are requ
 
 `block_state` can also accept block names as input, returning block's default state.
 
+Throws `unknown_block` if the provided input is not valid.
+
 <pre>
 set(x,y,z,'iron_trapdoor','half','top'); block_state(x,y,z)  => {waterlogged: false, half: top, open: false, ...}
 set(x,y,z,'iron_trapdoor','half','top'); block_state(x,y,z,'half')  => top
@@ -2347,6 +2421,8 @@ Without arguments, returns list of available tags, with block supplied (either b
 of tags the block belongs to, and if a tag is specified, returns `null` if tag is invalid, `false` if this block doesn't belong 
 to this tag, and `true` if the block belongs to the tag.
 
+Throws `unknown_block` if `block` doesn't exist
+
 ### `block_data(pos)`
 
 Return NBT string associated with specific location, or null if the block does not carry block data. Can be currently 
@@ -2381,9 +2457,9 @@ poi(x,y,z,5) => [['nether_portal',0,[7,8,9]],['nether_portal',0,[7,9,9]]] // two
 
 Without arguments, returns the list of biomes in the world.
 
-With block, or name, returns the name of the biome in that position, or null, if provided biome is not valid. 
+With block, or name, returns the name of the biome in that position, or throws `'unknown_biome'` if provided biome or block are not valid. 
 
-With an optional feature, it returns value for the specified attribute for that biome. Available and querable features include:
+With an optional feature, it returns value for the specified attribute for that biome. Available and queryable features include:
 * `'top_material'`: unlocalized block representing the top surface material
 * `'under_material'`: unlocalized block representing what sits below topsoil
 * `'category'`: the parent biome this biome is derived from. Possible values include:
@@ -2772,6 +2848,7 @@ If structure is not specified, it will return a set of structure names that are
 as keys, and same type of map values as with a single structure call. An empty set or an empty map would indicate that nothing
 should be generated there.
 
+Throws `unknown_structure` if structure doesn't exist.
 
 ### `structures(pos), structures(pos, structure_name)`
 
@@ -2805,6 +2882,8 @@ structure starts.
 Requires a `Structure Variant` or `Standard Structure` name (see above). If standard name is used, the variant of the 
 structure may depend on the biome, otherwise the default structure for this type will be generated.
 
+Throws `unknown_structure` if structure doesn't exist.
+
 ### `plop(pos, what)`
 
 Plops a structure or a feature at a given `pos`, so block, triple position coordinates or a list of coordinates. 
@@ -2827,7 +2906,9 @@ All generated structures will retain their properties, like mob spawning, howeve
 itself has certain rules to spawn mobs, like plopping a nether fortress in the overworld will not spawn nether mobs, 
 because nether mobs can spawn only in the nether, but plopped in the nether - will behave like a valid nether fortress.
 
-### `custom_dimension(name, seed?)`
+###  (deprecated) `custom_dimension(name, seed?)`
+
+Deprecated by `create_datapack()` which can be used to setup custom dimensions
 
 Ensures the dimension with the given `'name'` is available and configured with the given seed. It merely sets the world
 generator settings to the overworld, and the optional custom seed (or using current world seed, if not provided). 
@@ -3082,7 +3163,7 @@ Returns `true` if en entity is standing on firm ground and falling down due to t
 
 ### `query(e, 'name'), query(e, 'display_name'), query(e, 'custom_name'), query(e, 'type')`
 
-String of entity name
+String of entity name or formatted text in the case of `display_name`
 
 <pre>
 query(e,'name')  => Leatherworker
@@ -3808,14 +3889,16 @@ an inventory, all API functions typically do nothing and return null.
 
 Most items returned are in the form of a triple of item name, count, and nbt or the extra data associated with an item. 
 
-### item_list(tag?)
+### `item_list(tag?)`
 
 With no arguments, returns a list of all items in the game. With an item tag provided, list items matching the tag, or `null` if tag is not valid.
 
-### item_tags(item, tag?)
+### `item_tags(item, tag?)`
 
 Returns list of tags the item belongs to, or, if tag is provided, `true` if an item maches the tag, `false` if it doesn't and `null` if that's not a valid tag
 
+Throws `unknown_item` if item doesn't exist.
+
 ### `stack_limit(item)`
 
 Returns number indicating what is the stack limit for the item. Its typically 1 (non-stackable), 16 (like buckets), 
@@ -3823,6 +3906,8 @@ or 64 - rest. It is recommended to consult this, as other inventory API function
 it is up to the programmer to keep it at bay. As of 1.13, game checks for negative numbers and setting an item to 
 negative is the same as empty.
 
+Throws `unknown_item` if item doesn't exist.
+
 <pre>
 stack_limit('wooden_axe') => 1
 stack_limit('ender_pearl') => 16
@@ -3833,6 +3918,8 @@ stack_limit('stone') => 64
 
 Returns the string representing the category of a given item, like `building_blocks`, `combat`, or `tools`.
 
+Throws `unknown_item` if item doesn't exist.
+
 <pre>
 item_category('wooden_axe') => tools
 item_category('ender_pearl') => misc
@@ -3955,6 +4042,8 @@ while( (slot = inventory_find(p, 'diamond', slot)) != null, 41, drop_item(p, slo
 inventory_drop(x,y,z, 0) => 64 // removed and spawned in the world a full stack of items
 </pre>
 
+Throws `unknown_item` if item doesn't exist.
+
 ### `inventory_remove(inventory, item, amount?)`
 
 Removes amount (defaults to 1) of item from inventory. If the inventory doesn't have the defined amount, nothing 
@@ -4357,6 +4446,8 @@ Adds a new objective to scoreboard. If `criterion` is not specified, assumes `'d
 If the objective already exists, changes the criterion of that objective and returns `false`. If the criterion was not specified but the objective already exists, returns the current criterion.
 If the objective was added, returns `true`. If nothing is affected, returns `null`
 
+Throws `unknown_criterion` if criterion doesn't exist.
+
 <pre>
 scoreboard_add('counter')
 scoreboard_add('lvl','level')
@@ -4520,6 +4611,8 @@ Valid mixer options are `master`, `music`, `record`, `weather`, `block`, `hostil
 and `voice`. `pos` can be either a block, triple of coords, or a list of thee numbers. Uses the same options as a
  corresponding `playsound` command.
  
+Throws `unknown_sound` if sound doesn't exist.
+
 ## Particles
 
 ### `particle(name, pos, count?. spread?, speed?, player?)`
@@ -4529,12 +4622,15 @@ of 0, and to all players nearby, but these options can be changed via optional a
 command on details on those options. Valid particle names are 
 for example `'angry_villager', 'item diamond', 'block stone', 'dust 0.8 0.1 0.1 4'`.
 
+Throws `unknown_particle` if particle doesn't exist.
+
 ### `particle_line(name, pos, pos2, density?, player?)`
 
 Renders a line of particles from point `pos` to `pos2` with supplied density (defaults to 1), which indicates how far 
 apart you would want particles to appear, so `0.1` means one every 10cm. If a player (or player name) is supplied, only
 that player will receive particles.
 
+Throws `unknown_particle` if particle doesn't exist.
 
 ### `particle_box(name, pos, pos2, density?, player?)`
 ### `particle_rect` (deprecated)
@@ -4542,6 +4638,8 @@ that player will receive particles.
 Renders a cuboid of particles between points `pos` and `pos2` with supplied density. If a player (or player name) is 
 supplied, only that player will receive particles.
 
+Throws `unknown_particle` if particle doesn't exist.
+
 ## Markers
 
 ### `draw_shape(shape, duration, key?, value?, ... )`, 
@@ -4828,6 +4926,10 @@ record to the file. Since files are closed after each write, sending multiple li
 write is beneficial for writing speed. To send multiple packs of data, either provide them flat or as a list in the
 third argument.
 
+Throws:
+- `nbt_read_error`: When failed to read NBT file.
+- `json_read_error`: When failed to read JSON file. The exception data will contain details about the problem.
+
 <pre>
 write_file('foo', 'shared_text, ['one', 'two']);
 write_file('foo', 'shared_text', 'three\n', 'four\n');
@@ -4879,6 +4981,8 @@ specific data directory is under `world/scripts/foo.data/bar/../baz.nbt`, and sh
 
 You can use app data to save non-vanilla information separately from the world and other scripts.
 
+Throws `nbt_read_error` if failed to read app data.
+
 ### `store_app_data(tag)`
 
 Note:  `store_app_data(tag, file)` and `store_app_data(tag, file, shared?)` usages deprecated. Use `write_file` instead.
@@ -4893,6 +4997,83 @@ Returns `true` if the file was saved successfully, `false` otherwise.
 
 Uses the same file structure for exclusive app data, and shared data folder as `load_app_data`.
 
+### `create_datapack(name, data)`
+
+Creates and loads custom datapack. The data has to be a map representing the file structure and the content of the 
+json files of the target pack.
+
+Returns `null` if the pack with this name already exists or is loaded, meaning no change has been made.
+Returns `false` if adding of the datapack wasn't successful.
+Returns `true` if creation and loading of the datapack was successful. Loading of a datapack results in
+reloading of all other datapacks (vanilla restrictions, identical to /datapack enable), however unlike with `/reload` 
+command, scarpet apps will not be reloaded by adding a datapack using `create_datapack`.
+
+Currently, only json files are supported in the packs. `'pack.mcmeta'` file is added automatically.
+
+Reloading of datapacks that define new dimensions is not implemented in vanilla. Vanilla game only loads 
+dimension information on server start. `create_datapack` is therefore a direct replacement of manually ploping of the specified 
+file structure in a datapack file and calling `/datapack enable` on the new datapack with all its quirks and sideeffects
+(like no worldgen changes, reloading all other datapacks, etc.). To enable newly added custom dimensions, call much more
+experimental `check_hidden_dimensions()` after adding a datapack if needed.
+
+Synopsis:
+<pre>
+script run create_datapack('foo', 
+{
+    'foo' -> {
+        'bar.json' -> {
+            'c' -> true,
+            'd' -> false,
+            'e' -> {'foo' -> [1,2,3]},
+            'a' -> 'foobar',
+            'b' -> 5
+        }
+    }
+})
+
+script run create_datapack('funky_world',  {
+    'data' -> {
+        'minecraft' -> {
+            'dimension' -> {
+                'custom_ow.json' -> { 
+                    'type' -> 'minecraft:the_end',
+                    'generator' -> {
+                        'biome_source' -> {
+                             'seed' -> 0,
+                             'large_biomes' -> false,
+                             'type' -> 'minecraft:vanilla_layered'
+                        },
+                        'seed' -> 0,
+                        'settings' -> 'minecraft:nether',
+                        'type' -> 'minecraft:noise'
+                    }
+                }
+            }
+        }
+    }
+});
+check_hidden_dimensions();  => ['funky_world']
+        
+</pre>
+
+### `enable_hidden_dimensions()`
+
+The function reads current datapack settings detecting new dimensions defined by these datapacks that have not yet been added
+to the list of current dimensions and adds them so that they can be used and accessed right away. It doesn't matter how the
+datapacks have been added to the game, either with 'create_datapack()' or manually by dropping a datapack file and calling 
+`/datapack enable` on it. Returns the list of valid dimension names / identifiers that has been added in the process.
+
+Fine print: The function should be
+considered experimental. There 'should not be' (famous last words) any side-effects if no worlds are added. Already connected
+clients will not see suggestions for commands that use dimensions `/execute in <dim>` (vanilla client limitation) 
+but all commands should work just fine with
+the new dimensions. Existing worlds that have gotten modified settings by the datapacks will not be reloaded or replaced.
+The usability of the dimensions added this way has not been fully tested, but it seems it works just fine. Generator settings
+for the new dimensions will not be added to `'level.dat'` but it will be added there automatically next time the game restarts by 
+vanilla. One could have said to use this method with caution, and the authors take no responsibility of any losses incurred due to 
+mis-handlilng of the temporary added dimensions, yet the feature itself (custom dimensions) is clearly experimental for Mojang 
+themselves, so that's about it.
+
 ### `tick_time()`
 
 Returns server tick counter. Can be used to run certain operations every n-th ticks, or to count in-game time.
@@ -4956,6 +5137,8 @@ Evaluates the expression `expr` with different dimension execution context. `smt
 world-localized block, so not `block('stone')`, or a string representing a dimension like:
  `'nether'`, `'the_nether'`, `'end'` or `'overworld'`, etc.
  
+Throws `unknown_dimension` if provided dimension can't be found.
+ 
 ### `view_distance()`
 Returns the view distance of the server.
 
@@ -5010,6 +5193,7 @@ Available options in the scarpet app space:
  Relevant world related properties
   * `world_name` - name of the world
   * `world_seed` - a numeric seed of the world
+  * `world_dimensions` - a list of dimensions in the world
   * `world_path` - full path to the world saves folder
   * `world_folder` - name of the direct folder in the saves that holds world files
   * `world_carpet_rules` - returns all Carpet rules in a map form (`rule`->`value`). Note that the values are always returned as strings, so you can't do boolean comparisons directly. Includes rules from extensions with their namespace (`namespace:rule`->`value`). You can later listen to rule changes with the `on_carpet_rule_changes(rule, newValue)` event.