Wikifunctions:Reserved ZIDs

The wiki of functions currently loads a few static ZObjects on setup. We will over time need a few more of these.

This page is about the fun bike-shedding discussion of how many ZIDs we should reserve, whether they have to be contiguous, and what these first ZIDs should be. This can also be a place for planting easter eggs, a feature that has proven rather popular in Wikidata.

Note that, in order to simplify the discussion, we currently do not think about the future possibility of having federated instances of the software running the wiki of functions, and how that will work. We are solely thinking about which ZIDs for the wiki of functions itself should be reserved.

Should the reserved ZIDs be contiguous?

Yes.

There is a certain simplicity in saying “all ZIDs with 4 digits or less are reserved”.

There is also the hybrid model of reserving all ZIDs below a certain number, and additionally reserving some bigger ZIDs for easter eggs or specific reasons (that's what Wikidata did).

How many ZIDs should we reserve?

Let's reserve all ZIDs with four digits or less.

All core objects would be in the ZIDs with three digits and fewer, and we keep the four-digit ZIDs for languages.

This follows roughly the proposals made by community members on the talk page and on Phabricator. In particular, we also won't pack the space.

Currently reserved ZIDs

Tracked in Phabricator:
Task T258914

The following is subject to change and open to discussion. Some explanation following to maybe help with remembering (although it shouldn't be necessary to learn them).

See Wikifunctions:Reserved ZIDs/all for a list of currently pre-defined objects.

Ranges

We reserve certain spaces for certain kinds of pre-defined objects.

Z1 – Z99: core types. (See § Core types below.)
Z100 – Z199: validators for the core types (i.e. for each core type, +100 gives the validator), e.g. Z104 is the validator for Z4/Type
Z200 – Z299: built-in implementations for the validators for the core types (i.e. Z204 is the built-in implementation for the validator for Z4/Type)
Z300 – Z399: unassigned for now
Z400 – Z499: reserved for local use
Z500 – Z599: core error types (Z5xx because Z5 is error) (See § Core error types below.)
Z600 – Z699: core programming languages (Z6xx because Z61 is programming language)
Z700 – Z799: unassigned for now
Z800 – Z899: definitions of core functions with built-ins (Z8xx because Z8 is function) (See § Core functions below.)
Z900 – Z999: built-ins for the core functions (they are +100 from the respective Z8xx)
Z1000 – Z2999: natural languages (instances of Z60)
Z3000 – Z5999: reserved for future use
Z6000 – Z6999: Types, Functions, etc. for fetching and using Wikidata and other Wikimedia sources
Z7000 – Z7999: experimental, used for NLG, will be changed
Z8000 – Z8999: Testers for each pre-defined function (e.g. Z801 is tested via Z8010, Z8011, Z8012, … Z8019).
Z9000 – Z9999: reserved for future use

Core types

Z1: ZObject, the root.
Z2: Persistent object (Type): everything on the wiki is a Z2, that's why this has such a low ZID.
Z3: Key (Type): because the word key has three letters in English.
Z4: Type (Type): because the word type has four letters in English.
Z5: Error (Type): because the word error has five letters in English. (See § Core error types below.)
Z6: String (Type): because the word string has six letters in English.
Z7: Function call (Type): because function calls are the main magic of the system, and 7 is a magic number. It is also close to Z8.
Z8: Function (generic type, thus technically a function): because function has eight letters in English. (See § Core functions below.)
Z9: Reference (Type): because the word reference has nine letters in English.
Z10: List (generic type, thus technically a function): because it's the first number that has two digits.
Z11: Monolingual text (Type): because it is just one language, and there's a one in the name.
Z12: Multilingual text (Type): because it's an extension of Z11.
Z13: empty list (List): nature abhors vacuum, and people dislike 13.
Z14: Implementation (Type): because the word implementation has fourteen letters in English.
Z15: Not yet assigned.
Z16: Code (Type): no good reason, it's close to Z14, and Z61/Programming language.
Z17: Argument declaration (Type).
Z18: Argument reference (Type).
Z19: Not yet assigned.
Z20: Tester (Type): because 20/20 is perfect vision, and tests make errors visible.
Z21: Unit (Type).
Z22: Evaluation result (Type).
Z23: Nothing (Type).
Z24: void (Unit).
Z25: Not yet assigned.
Z26: Not yet assigned.
Z27: Not yet assigned.
Z28: Not yet assigned.
Z29: Not yet assigned.
Z30: Not yet assigned.
Z31: Monolingual textset (Type).
Z32: Multilingual textset (Type): because it's an extension of Z31.
Z33: Not yet assigned.
Z34: Not yet assigned.
Z35: Not yet assigned.
Z36: Not yet assigned.
Z37: Not yet assigned.
Z38: Not yet assigned.
Z39: Key reference (Type): because Z3/Key Z9/Reference.
Z40: Boolean (Type): because Boole first published in (18)40.
Z41: true (Boolean).
Z42: false (Boolean).
Z43: Not yet assigned.
Z44: Not yet assigned.
Z45: Not yet assigned.
Z46: Not yet assigned.
Z47: Not yet assigned.
Z48: Not yet assigned.
Z49: Not yet assigned.
Z50: Error type (Type): because Error is Z5.
Z60: Natural language (Type): because Z6 is a string.
Z61: Programming language (Type): because Z16 is code.
Z80: Byte (Type): because it is an octet.
Z84: Union (Type).
Z85: Not yet assigned.
Z86: Code point (Type): because it is not exactly a Z80/Byte, but more like Z6/String.
Z99: Quote (Type): because it looks a bit like a closing quotation mark in English.

Core functions

Z801 Echo: T ➝ T
returns the input unchanged
Z802 If: Boolean, T, T ➝ T
returns second argument if the first is true, else the third; if has two letters
Z803 Value by key: Key reference, Any ➝ Any
returns the value by key from the object; Z3/Key
Z805 Reify: Any ➝ List(Pair(Key reference, Any))
transform any object into a list of key-value pairs; reify has five letters
Z808 Abstract: List(Pair(Key reference, Any)) ➝ Any
transform a list of key-value pairs into an object; abstract has eight letters.
Z810 Prepend element to list: T, List(T) ➝ List(T)
insert an object to the beginning of an ordered list of objects (because Z10 is list).
Z811 First element: List(T) ➝ T
get the first item in an ordered list of objects (because Z10 is list and we get the first)
Z812 List without first element: List(T) ➝ List(T)
get the list without the first object (because Z10 is list and we get the second, the rest)
Z813 Empty: List(T) ➝ Boolean
return if a list does not contain any item (because Z13 is empty list).
Z820 Trigger Metadata: String, Any ➝ Any
take the given value (an error or other metadata) and emits it in the function call response envelope under the name of the String input.
Z821 First: Pair(T1, T2) ➝ T1
extract the first value of a pair (because Z22 is pair).
Z822 Second: Pair(T1, T2) ➝ T2
extract the second value of a pair (because Z22 is pair).
Z844 Boolean equality: Boolean, Boolean ➝ Boolean
returns true if the two inputs are the same, false otherwise
Z860 Language code to language: String ➝ Language
takes a language code given as a string and returns a natural language object
Z866 String equality: String, String ➝ Boolean
returns true if the two inputs are the same, false otherwise
Z868 Convert: String ➝ List(Character)
convert a string into a list of Characters, because Z6/String and Z86/Character.
Z873 Map: Function, List ➝ List
Returns a list where each of the Z1/objects of an input Z881/List has been processed by the given Z8/Function
Z876 Reduce: Function, List, Object ➝ Object
Returns a value after running the given Function on each object of the List, starting with the given Object
Z868 Convert: String ➝ List(Character)
convert a string into a list of Characters, because Z6/String and Z86/Character.
Z881Typed list: Type ➝ Type
takes a type and returns a type of a list of elements of that type
Z882Typed pair: Type, Type ➝ Type
takes two types and returns a type representing a pair of these
Z883Map: … ➝ …
…
Z884Union: T, T ➝ T
takes two types and returns a type that accepts either
Z885Error type to type: Error type ➝ Type
takes an error type and creates a type out of it
Z886Convert: List*(Character) ➝ String
convert a list of Characters into a string, because Z86/Character and Z6/String.
Z887Reduce: … ➝ …
…
Z888 Same: Character, Character ➝ Boolean
compare two characters and return if they are equal.
Z899 Unquote: Quote ➝ Any
Unquotes a ZObject, because Z99/Quote.

Core error types

Z501 (error message, input): syntax error
Z502 (subtype, value): not wellformed, points to Z52x or Z53x
Z503 (function name): not implemented yet
Z504 (zid): Zid not found
Z505 (expected, actual, args): number of arguments mismatch
Z506 (expected, actual, arg): argument type mismatches
Z507 (function call): error in evaluation
Z508 (object): competing keys
Z509 (errors): List of errors
Z510 (none): nil
Z511 (key reference, object): key not found
Z512 (object): Z9 error
Z513 (resolved object): resolved object without Z2K2
Z514 (implementation): Builtin does not exist
Z515 (implementation): Builtin ID is erroneous
Z516 (key, bad value): Argument value error
Z517 (expected type, actual type, returned value, propagated error): Return type mismatch
Z518 (expected type, object, propagated error): Object type mismatch
Z519 (object): Undefined list type
Z520 (object): Wrong list type
Z521 (offending value): ZObjects must not be number or boolean or null
Z522 (offending index in array, propagated error): Array element not well formed
Z523 (object): Missing Z1K1
Z524 (value of Z1K1): Z1K1 must not be a string or array
Z525 (key): Invalid key
Z526 (key, propagated error): not wellformed value
Z531 (whole object): Z6 must have 2 keys
Z532 (whole object): Z6 without a Z6K1
Z533 (value of Z6K1): Z6K1 must be a string
Z534 (whole object): Z9 must have 2 keys
Z535 (whole object): Z9 without a Z9K1
Z536 (value of Z9K1): Z9K1 must be a string in JSON
Z537 (value of Z9K1): Z9K1 must look like a reference
Z538 (page title): wrong namespace
Z539 (page title): wrong content type
Z540 (language code): invalid language code
Z541 (language code): language code not found
Z542 (expected type, actual object): expected type, actual object
Z543 (type name): type not found
Z544 (type zid, type name, existing type name): conflicting type names
Z545 (type zid, type name, existing type zid): conflicting type Zids
Z546 (type zid, type name): builtin type not found
Z547 (input): invalid format
Z548 (error message, input): invalid JSON
Z549 (reference value): invalid ZReference
Z550 (reference value): unknown ZReference
Z551 (key, expected type, actual type): schema type mismatch
Z552 (index, expected type, actual type): array element type mismatch
Z553 (zobject): disallowed root type
Z554 (clashing ZID, language): label clashes with another ZObject's label
Z555 (ZID, title): mis-matched ZID and page title
Z556 (title): invalid page title
Z557 (error message): user does not have permission
Z558 (programming language): invalid programming language
Z559 (none): user not permitted to evaluate function
Z560 (evaluation result): invalid evaluation result
Z561 (propagated error): invalid evaluation request
Z562 (missing property): incomplete evaluation request
Z563 (call): call by non-reentrant executor
Z564 (contents): invalid executor response
Z565 (missing property): Incomplete executor request
Z570 (orchestrator rate limit): reached rate limit in orchestrator
Z571 (evaluator rate limit): reached rate limit in evaluator
Z572 (recursion limit, function name): reached recursion limit in orchestrator
Z573 (recursion limit, function name): reached recursion limit in evaluator
Z574 (time limit): reached time limit in orchestrator
Z575 (time limit): reached time limit in evaluator