NAME

Muldis::D::Dialect::HDMD_Perl5_STD - How to format Perl 5 Hosted Data Muldis D

VERSION

This document is Muldis::D::Dialect::HDMD_Perl5_STD version 0.107.0.

PREFACE

This document is part of the Muldis D language specification, whose root document is Muldis::D; you should read that root document before you read this one, which provides subservient details.

DESCRIPTION

This document outlines the grammar of the Hosted Data Muldis D standard dialect named HDMD_Perl5_STD. The fully-qualified name of this Muldis D standard dialect is [ 'Muldis_D', 'http://muldis.com', '0.107.0', 'HDMD_Perl5_STD' ].

The HDMD_Perl5_STD dialect is defined to be hosted in Perl 5, and is composed of just|mainly core Perl 5 types. This dialect is optimized for Perl 5 specifically, and doesn't try to match the version for Perl 6; you *will* have to reformat any Perl Hosted Data Muldis D when migrating between Perl 5 and Perl 6, same as with your ordinary Perl code.

This dialect is designed to exactly match the structure of a possible concrete syntax tree, comprised of native Perl 5 scalar and collection typed values, resulting from parsing code written in the Muldis D dialect PTMD_STD using Perl 5. This dialect exists as a convenience to Perl 5 programmers that want to generate or introspect Muldis D code by saving them the difficulty and overhead of escaping and stitching plain text code; it is expected that a Muldis D implementation written in Perl 5 will natively accept input in both the PTMD_STD and HDMD_Perl5_STD dialects. Furthermore, the HDMD_Perl5_STD dialect provides additional Muldis D syntax options to Perl 5 programmers besides what PTMD_STD would canonically parse into, such as the direct use of some Perl 5-only features.

Note that most of the details that the 2 dialects have in common are described just in the PTMD_STD file, for both dialects; this current file will mainly focus on the differences; you should read the Muldis::D::Dialect::PTMD_STD file before the current one, so to provide a context for better understanding it.

GENERAL STRUCTURE

A HDMD_Perl5_STD Muldis D code file is actually a Perl 5 code file that defines particular multi-dimensional Perl data structures which resemble possible concrete syntax trees (CSTs) from parsing PTMD_STD Muldis D code. Each component of a CST is called a node or node element, and roughly corresponds to a capture by the PTMD_STD parser. A node is typically represened as a Perl array ref, but could alternately be a Perl scalar or something else, and so HDMD_Perl5_STD Muldis D code is typically a tree of Perl structures, called node trees, with Perl array refs as the central nodes and Perl scalars as the leaf nodes. Often HDMD_Perl5_STD code is embedded or constructed in one or more files of a larger Perl 5 program that does more than define this code, such as various non-database-related tasks. A node tree is just composed using basic Perl data types, and there are no Muldis D node-specific Perl classes or objects required for doing this.

Note that Perl undefined values are not allowed anywhere in a node in the general case; you must use only defined values instead. This documentation also assumes that only defined values are used, and that supplying a Perl undef will result in an error. The few exceptions to this rule are explicitly stated.

The grammar in this file is informal and consists just of written descriptions of how each kind of node must be composed and how to interpret such Perl data structures as Muldis D code. Every named grammar node is a Perl array ref unless otherwise stated, and every grammar element is an array element; the first node element is the array element at index zero, and so on.

The root grammar node for the entire dialect is Muldis_D.

START

A Muldis_D node has 2 ordered elements where the first element is a language_name node and the second element is either a value node or a depot node.

See the pod sections in this file named "LANGUAGE NAME", "VALUE LITERALS AND SELECTORS", and "DEPOT SPECIFICATION", for more details about the aforementioned tokens/nodes.

When Muldis D is being compiled and invoked piecemeal, such as because the Muldis D implementing virtual machine (VM) is attached to an interactive user terminal, or the VM is embedded in a host language where code in the host language invokes Muldis D code at various times, many value may be fed to the VM directly for inter-language exchange, and not every one would then have its own language_name. Usually a language_name would be supplied to the Muldis D VM just once as a VM configuration step, which provides a context for further interaction with the VM that just involves Muldis D code that isn't itself qualified with a language_name.

LANGUAGE NAME

As per the VERSIONING pod section of Muldis::D, code written in Muldis D must start by declaring the fully-qualified Muldis D language name it is written in. The HDMD_Perl5_STD dialect formats this name as a language_name node having 5 ordered elements:

ln_base_name

This is the Muldis D language base name; it is simply the Perl character string Muldis_D.

ln_base_authority

This is the base authority; it is a character string formatted as per a specific-context Name value literal; it is typically the Perl character string http://muldis.com.

ln_base_version_number

This is the base version number; it is a character string formatted as per ln_base_authority; it is typically a character string like 0.107.0.

ln_dialect

This is the dialect name; it is simply the Perl character string HDMD_Perl5_STD.

ln_extensions

This is a set of chosen pragma/parser-config options, which is formatted similarly to a Tuple SCVL. The only mandatory pragma is catalog_abstraction_level (see the "CATALOG ABSTRACTION LEVELS" pod section). The only optional pragma is standard_syntax_extensions (see the "STANDARD SYNTAX EXTENSIONS" pod section). Other pragmas may be added later, which would likely be optional.

The value associated with the ln_extensions attribute named catalog_abstraction_level must be one of these 4 Perl character strings: the_floor, code_as_data, plain_rtn_inv, rtn_inv_alt_syn.

The value associated with the ln_extensions attribute named standard_syntax_extensions must be formatted similarly to a Set SCVL; each of the value's elements must be one of these 1 Perl character strings: date_time.

Examples:

[ 'Muldis_D', 'http://muldis.com', '0.107.0', 'HDMD_Perl5_STD', {
    catalog_abstraction_level => 'rtn_inv_alt_syn'
} ]

[ 'Muldis_D', 'http://muldis.com', '0.107.0', 'HDMD_Perl5_STD', {
    catalog_abstraction_level  => 'rtn_inv_alt_syn',
    standard_syntax_extensions => ['date_time']
} ]

CATALOG ABSTRACTION LEVELS

The catalog_abstraction_level pragma determines with a broad granularity how large the effective Muldis D grammar is that a programmer may employ with their Muldis D code.

The catalog abstraction level of some Muldis D code is a measure of how much or how little that code would resemble the system catalog data that the code would parse into. The lower the abstraction level, the smaller and simpler the used Muldis D grammar is and the more like data structure literals it is; the higher the abstraction level, the larger and more complicated the Muldis D grammar is and the more like general-purpose-language typical code it is.

There are currently 4 specified catalog abstraction levels, which when arranged from lowest to highest amount of abstraction, are: the_floor, code_as_data, plain_rtn_inv, rtn_inv_alt_syn. Every abstraction level has a proper superset of the grammar of every other abstraction level that is lower than itself, so for example any code that is valid code_as_data is also valid plain_rtn_inv, and so on.

the_floor

This abstraction level exists more as an academic exercise and is not intended to actually be used.

Examples:

[
    [ 'Muldis_D', 'http://muldis.com', '0.107.0', 'HDMD_Perl5_STD', {
        catalog_abstraction_level => 'the_floor'
    } ],
    [ 'Relation', [
        {
            food => [ 'Scalar', 'Text', [ nfd_codes => {
                '' => ['Scalar',
                    'String.<67><97><114><114><111><116><115>',{}]
            } ] ],
            qty => [ 'Scalar', 'Int', {
                '' => ['Scalar','String.<100>',{}]
            } ]
        },
        {
            food => [ 'Scalar', 'Text', [ nfd_codes => {
                '' => ['Scalar','String.<75><105><119><105><115>',{}]
            } ] ],
            qty => [ 'Scalar', 'Int', {
                '' => ['Scalar','String.<30>',{}]
            } ]
        }
    ] ]
]

code_as_data

This abstraction level is the best one for when you want to write code in exactly the same form as it would take in the system catalog.

Code written to the code_as_data level can employ all of the language grammar constructs described in these main pod sections: "VALUE LITERALS AND SELECTORS", "OPAQUE VALUE LITERALS", "COLLECTION VALUE SELECTORS".

Examples:

[
    [ 'Muldis_D', 'http://muldis.com', '0.107.0', 'HDMD_Perl5_STD', {
        catalog_abstraction_level => 'code_as_data'
    } ],
    [ 'Relation', [
        { food => 'Carrots', qty => 100 },
        { food => 'Kiwis', qty => 30 }
    ] ]
]

[
   [ 'Muldis_D', 'http://muldis.com', '0.107.0', 'HDMD_Perl5_STD', {
      catalog_abstraction_level => 'code_as_data'
   } ],
   [ 'depot', { 'depot-catalog' => [ 'Database', 'Depot', {
      functions => [ 'Relation', [
         {
            name => ['Name','cube'],
            material => [ 'Tuple', 'Function', {
               result_type => ['PNSQNameChain','Int'],
               params => [ 'Relation', 'NameTypeMap', [
                  { name => ['Name','topic'],
                     type => ['PNSQNameChain','Int'] }
               ] ],
               expr => [ 'Database', 'ExprNodeSet', {
                  sca_val_exprs => [ 'Relation', [
                     { name => ['Name','INT_3'], value => 3 }
                  ] ],
                  func_invo_exprs => [ 'Relation', [
                     {
                        name => ['Name',''],
                        function => ['PNSQNameChain','Integer.power'],
                        args => [ 'Relation', 'NameExprMap', [
                           { name => ['Name','radix'],
                              expr => ['Name','topic'] },
                           { name => ['Name','exponent'],
                              expr => ['Name','INT_3'] }
                        ] ]
                     }
                  ] ]
               } ]
            } ]
         }
      ] ]
   } ] } ]
]

plain_rtn_inv

This abstraction level is the lowest one that can be recommended for general use.

Code written to the plain_rtn_inv level can employ all of the language grammar constructs that code_as_data can, plus all of those described in these main pod sections: "GENERIC VALUE EXPRESSIONS".

Examples:

[
    [ 'Muldis_D', 'http://muldis.com', '0.107.0', 'HDMD_Perl5_STD', {
        catalog_abstraction_level => 'plain_rtn_inv'
    } ],
    [ 'depot', { 'depot-catalog' => [
        [ 'function', 'cube', [ 'Int', { topic => 'Int' }, [
            [ 'func-invo', 'Integer.power',
                { radix => ['$','topic'], exponent => 3 } ]
        ] ] ]
    ] } ]
]

rtn_inv_alt_syn

This abstraction level is the highest one and is the most recommended one for general use.

Code written to the rtn_inv_alt_syn level can employ all of the language grammar constructs that plain_rtn_inv can, plus all of those described in these main pod sections: "FUNCTION INVOCATION ALTERNATE SYNTAX EXPRESSIONS".

Examples:

[
    [ 'Muldis_D', 'http://muldis.com', '0.107.0', 'HDMD_Perl5_STD', {
        catalog_abstraction_level => 'rtn_inv_alt_syn'
    } ],
    [ 'depot', { 'depot-catalog' => [
        [ 'function', 'cube', [ 'Int', { topic => 'Int' }, [
            [ 'op', 'I^', [ ['$','topic'], 3 ] ]
        ] ] ]
    ] } ]
]

STANDARD SYNTAX EXTENSIONS

The standard_syntax_extensions pragma declares which optional portions of the Muldis D grammar a programmer may employ with their Muldis D code.

There is currently 1 specified standard syntax extension: date_time. These are all mutually independent and any or all may be used at once.

While each standard syntax extension is closely related to a Muldis D language extension, you can use the latter's types and routines without declaring the former; you only declare you are using a standard syntax extension if you want the Muldis D parser to recognize special syntax specific to those types and routines, and otherwise you just use them using the generic syntax provided for all types and routines.

The standard_syntax_extensions pragma is generally orthogonal to the catalog_abstraction_level pragma, so you can combine any value of the latter with any value-list of the former. However, in practice all standard syntax extensions will have no effect when the catalog abstraction level is the_floor, and some of their features may only take effect when the catalog abstraction level is rtn_inv_alt_syn, as is appropriate.

Specifying the standard_syntax_extensions pragma is optional, and when omitted it defaults to the empty set, meaning no extensions may be used.

date_time

The date_time standard syntax extension is closely related to the Muldis::D::Ext::DateTime language extension, and it constitutes special syntax for its data types; in the future it may improve the type syntax or add syntax for operators.

VALUE LITERALS AND SELECTORS

A value node is a Muldis D value literal, which is a common special case of a Muldis D value selector.

There are 25 main varieties of value node, each of which is a named node kind of its own: Bool, Order, RatRoundMeth, Int, Rat, Blob, Text, Name, NameChain, PNSQNameChain, Comment, Instant, Duration, RatRoundRule, String, Scalar, Tuple, Database, Relation, Set, Maybe, Array, Bag, [S|M]PInterval.

Fundamentally, the various Muldis D scalar and collection types are represented by their equivalent Perl native scalar and collection types. But since Muldis D is more strongly typed, or at least differently typed, than Perl, each value node is represented by a Perl array ref, whose elements include both the payload Perl literal plus explicit meta-data for how to interpret that Perl literal for mapping to Muldis D.

Value Literal Common Elements

Every value node is either a GCVL (generic context value literal) or a SCVL (specific context value literal).

Every GCVL has 1-3 ordered elements:

value_kind

This is a character string of the format <[A..Z]> <[ a..z A..Z ]>+; it identifies the data type of the value literal in broad terms and is the only external meta-data of value_payload generally necessary to interpret the latter; what grammars are valid for value_payload depend just on value_kind.

For just some data types, the value_kind may be omitted; see below.

type_name

Only when the value node has 3 elements: This is a Muldis D data type name, for example sys.std.Core.Type.Int; it identifies a specific subtype of the generic type denoted by value_kind, and serves as an assertion that the Muldis D value denoted by value_payload is a member of the named subtype. Its format is a PNSQNameChain_payload node. Iff value_kind is [|DH]Scalar then type_name is mandatory; otherwise, type_name is optional for all value, except that type_name must be omitted when value_kind is one of the 2 [Bool, Order]; this isn't because those 2 types can't be subtyped, but because in practice doing so isn't useful.

value_payload

This is mandatory for all value. Format varies with value_kind.

For some data types, a GCVL may alternately be just its payload for the sake of brevity. If any Perl value of one of the following types is encountered where a GCVL node is expected, then it is interpreted as a full value node as follows:

Muldis D <- Perl 5
--------------------
Int  <- BigInt object or Perl scalar that looks like an integer
Rat  <- BigRat|BigNum obj or Perl scal that looks like num but not int
Text <- Perl scalar that doesn't look like a number

Or specifically, Int or Rat is assumed if the Perl value agrees with a canonical payload format according to the Int|Rat node definitions, or the value is otherwise interpreted as Text by default. If your data is such that the assumption might be wrong, then just use a full node to force the desired behaviour.

For GCVL and SCVL examples, see the subsequent documentation sections.

OPAQUE VALUE LITERALS

Boolean Literals

A Bool node represents a logical boolean value. It is interpreted as a Muldis D sys.std.Core.Type.Bool value as follows:

The canonical payload is the specific result of a Perl logical expression, such as (1 == 0) for Bool:False or (1 == 1) for Bool:True; said values are probably the empty string and number 1, respectively.
A few alternative payload formats are supported: The Perl value literals ['False', '0', 0, '', '⊥'] all map to Bool:False, and the Perl value literals ['True', '1', 1, '⊤'] all map to Bool:True.

Examples:

['Bool','True']

['Bool',(1 == 0)]

['Bool','⊤']

Order-Determination Literals

An Order node represents an order-determination. It is interpreted as a Muldis D sys.std.Core.Type.Cat.Order value as follows:

The canonical payload is the specific result of a Perl order-determining expression, such as (1 <=> 2) for Order:Increase or (1 <=> 1) for Order:Same or (2 <=> 1) for Order:Decrease; said values are probably the numbers [-1,0,1], respectively.
A few alternative payload formats are supported: The Perl value literals ['Increase', '-1', -1] all map to Order:Increase, the Perl value literals ['Same', '0', 0] all map to Order:Same, and the Perl value literals ['Decrease', '1', 1] all map to Order:Decrease.

Examples:

['Order','Same']

['Order',(2 <=> 1)]

Rational Rounding Method Literals

A RatRoundMeth node represents a rational rounding method. It is interpreted as a Muldis D sys.std.Core.Type.Cat.RatRoundMeth value by directly mapping the payload. The payload must be a Perl character string having one of the 7 values HalfDown, HalfUp, HalfEven, ToFloor, ToCeiling, ToZero, ToInf.

Examples:

['RatRoundMeth','HalfUp']

['RatRoundMeth','ToZero']

General Purpose Integer Numeric Literals

An Int node represents an integer numeric value. It is interpreted as a Muldis D sys.std.Core.Type.Int value as follows:

If the payload is a Perl scalar, then it must be just a canonical integer value according to Perl, and it is mapped directly; since native Perl integers are limited precision, larger integers can be represented by a Perl character string of the format 0 or \-?<[1..9]>['_'?<[0..9]>+]* that is interpreted as base 10.
An alternative payload format is a bigint object, which is conceptually the closest thing Perl 5 has in core to a "big integer".
If the payload is a Perl hash ref, then it must have 1 element, whose key and value are designated, in order, max-col-val and main payload; the max-col-val must be a Perl string composed of a single [ 1..9 A..Z ] character, and the main payload must be a Perl character string of the format 0 or \-?<[ 1..9 A..Z ]>['_'?<[ 0..9 A..Z ]>+]*. The main payload is interpreted as a base-N integer where N might be between 2 and 36, and the given max-col-val says which possible value of N to use. Assuming all column values are between zero and N-minus-one, the max-col-val contains that N-minus-one. So to specify, eg, bases [2,8,10,16], use max-col-val of [1,7,9,F].

Examples:

[ 'Int', { 1 => '11001001' } ] # binary #

[ 'Int', { 7 => '0' } ] # octal #

[ 'Int', { 7 => '644' } ] # octal #

-34 # decimal #

42 # decimal #

[ 'Int', { F => 'DEADBEEF' } ] # hexadecimal #

[ 'Int', { Z => '-HELLOWORLD' } ] # base-36 #

[ 'Int', { 3 => '301' } ] # base-4 #

[ 'Int', { B => 'A09B' } ] # base-12 #

General Purpose Rational Numeric Literals

A Rat node represents a rational numeric value. It is interpreted as a Muldis D sys.std.Core.Type.Rat value as follows:

If the payload is a Perl scalar, then it must be just a canonical numeric value according to Perl, and it is mapped directly; since native Perl numerics are limited precision or are inexact (IEEE float), larger numerics can be represented by a Perl character string of the format 0\.['_'?<[0..9]>+]+ or \-?<[1..9]>['_'?<[0..9]>+]*\.['_'?<[0..9]>+]+ that is interpreted as base 10.
An alternative payload format is a bigrat|bignum|bigint object, which is conceptually the closest thing Perl 5 has in core to a "big rational".
If the payload is a Perl array ref, then the payload must have exactly 2 or 3 elements, each of which constitutes a valid payload of an Int node. If the payload has 2 elements, then the rational's value is interpreted as the first element (a numerator) divided by the second (a denominator). If the payload has 3 elements, then the rational's value is interpreted as the first element (a mantissa) multiplied by the result of the second element (a radix) taken to the power of the third (an exponent).
If the payload is a Perl hash ref, then it must have 1 element, whose key and value are designated, in order, max-col-val and main payload; the max-col-val must be a Perl string composed of a single [ 1..9 A..Z ] character. If the main payload is a Perl scalar, then the main payload must be a Perl character string of the format 0\.['_'?<[ 0..9 A..Z ]>+]+ or \-?<[ 1..9 A..Z ]>['_'?<[ 0..9 A..Z ]>+]*\.['_'?<[ 0..9 A..Z ]>+]+. The main payload is interpreted as a base-N rational where N might be between 2 and 36, and the given max-col-val says which possible value of N to use. Assuming all column values are between zero and N-minus-one, the max-col-val contains that N-minus-one. So to specify, eg, bases [2,8,10,16], use max-col-val of [1,7,9,F]. If the main payload is a Perl array ref, then the main payload must have exactly 2 or 3 elements, and every pairwise combination of the max-col-val with the elements of the main payload must, when appropriately wrapped in a Perl hash ref, must constitute a valid hash ref payload for an Int node; the meaning of the 2 or 3 main payload elements is the same as the 2 or 3 payload elements mentioned in the previous bullet point.

Examples:

[ 'Rat', { 1 => '-1.1' } ]

-1.5 # same val as prev #

3.14159

[ 'Rat', { A => '0.0' } ]

[ 'Rat', { F => 'DEADBEEF.FACE' } ]

[ 'Rat', { Z => '0.000AZE' } ]

[ 'Rat', { 6 => ['500001','1000'] } ]

[ 'Rat', { B => ['A09B','A'] } ]

[ 'Rat', { 1 => ['1011101101','10','-11011'] } ]

[ 'Rat', [45207196,10,37] ]

[ 'Rat', [1,43] ]

[ 'Rat', [314159,10,-5] ]

General Purpose Binary String Literals

A Blob node represents a general purpose bit string. It is interpreted as a Muldis D sys.std.Core.Type.Blob value as follows:

If the payload is a Perl scalar, then it must be a canonical Perl bit string, which is a scalar whose utf-8 flag is false, and it is mapped directly.
If the payload is a Perl hash ref, then it must have 1 element, whose key and value are designated, in order, max-col-val and main payload; the max-col-val must be a Perl string composed of a single [137F] character, and the main payload must be a Perl character string of the format <[ 0..9 A..F ]>*. Each column of the main payload specifies a sequence of one of [1,2,3,4] bits, depending on whether max-col-val is [1,3,7,F].

Examples:

[ 'Blob', { 1 => '00101110100010' } ] # binary #

[ 'Blob', { 3 => '' } ]

[ 'Blob', { F => 'A705E' } ] # hexadecimal #

[ 'Blob', { 7 => '523504376' } ]

[ 'Blob', (pack 'H2', 'P') ]

[ 'Blob', (pack 'H2', 'Z') ]

General Purpose Character String Literals

A Text node represents a general purpose character string. It is interpreted as a Muldis D sys.std.Core.Type.Text value by directly mapping the payload. The payload must be just a canonical Perl character string, which is any Perl scalar value (a Muldis D implementation in Perl can ignore the utf-8 flag as Perl itself knows how to treat its strings consistently).

Examples:

[ 'Text', 'Ceres' ]

'サンプル' # note: needs "use utf8;" pragma to work #

''

'Perl'

"\N{LATIN SMALL LETTER OU}\x{263A}".chr(65)
    # note: \N{} needs "use charnames ':full';" pragma to work #

DBMS Entity Name Literals

A Name node represents a canonical short name for any kind of DBMS entity when declaring it; it is a character string type, that is disjoint from Text. It is interpreted as a Muldis D sys.std.Core.Type.Cat.Name value by directly mapping the payload. The payload must be as per the payload of a Text node.

A NameChain node represents a canonical long name for invoking a DBMS entity in some contexts; it is conceptually a sequence of entity short names. Its payload is a Perl array ref or character string. This node is interpreted as a Muldis D sys.std.Core.Type.Cat.NameChain value as follows:

If the payload is an array ref, then every element must be a valid payload for a Name node (that is, any Perl character string). Each element of the payload, in order, defines an element of the array possrep's attribute of a NameChain.
If the payload is a char str, then it must be formatted as a catenation (using period (.) separators) of at least 1 part, where each part can not have any literal period (.) characters (if you want literal periods then you can only use the array ref payload format to express it). The char str format of payload is interpreted by splitting it on the separators into the array ref format, then processed as per the latter. A zero part chain can only be expressed with the array ref payload format; an empty string char str format will be interpreted as having a single element that is the empty string.

Fundamentally a PNSQNameChain node is exactly the same as a NameChain node in format and interpretation, with the primary difference being that it may only define NameChain values that are also values of the proper subtype sys.std.Core.Type.Cat.PNSQNameChain, all of which are nonempty chains. Now that distinction alone wouldn't be enough rationale to have these 2 distinct node kinds, and so the secondary difference between the 2 provides that rationale; the PNSQNameChain node supports a number of chain value shorthands while the NameChain node supports none.

A PNSQNameChain node is interpreted the same as a NameChain node except for the extra restrictions and shorthands. If the first element of a PNSQNameChain payload is the empty string then the payload is treated as if the first element were instead topic.

Examples:

[ 'Name', 'login_pass' ]

[ 'Name', 'First Name' ]

[ 'NameChain', ['gene','sorted_person_name'] ]

[ 'NameChain', 'stats.samples by order' ]

[ 'NameChain', [] ]

['PNSQNameChain', ['fed','data','the_db','gene','sorted_person_names']]

['PNSQNameChain', 'fed.data.the_db.stats.samples by order']

['PNSQNameChain', '.attr']
    # same as ['PNSQNameChain', 'lex.topic.attr'] #

Code Comment Literals

A Comment node represents the text of a Muldis D code comment; it is a character string type, that is disjoint from both Text and Name. It is interpreted as a Muldis D sys.std.Core.Type.Cat.Comment value by directly mapping the payload. The payload must be as per the payload of a Text node.

Examples:

[ 'Comment', 'This does something.' ]

[ 'Comment', 'So does this.' ]

TAI Temporal Literals

An Instant node represents a single point in time which is specified in terms of atomic seconds; it is a rational numeric type, that is disjoint from both Rat and Duration. This node is interpreted as a Muldis D sys.std.Core.Type.Instant value by directly mapping the payload, which must be as per the payload of a Rat node.

A Duration node represents a single amount of time (the difference between two instants) which is specified in terms of atomic seconds; it is a rational numeric type, that is disjoint from both Rat and Instant. This node is interpreted as a Muldis D sys.std.Core.Type.Duration value by directly mapping the payload, which must be as per the payload of a Rat node.

Examples:

[ 'Instant', 1235556432.0 ]

[ 'Instant', 854309115.0 ]

[ 'Duration', 3600.0 ]

[ 'Duration', -50.0 ]

[ 'Duration', 3.14159 ]

[ 'Duration', { 1 => ['1011101101','10','-11011'] } ]

[ 'Duration', [1,43] ]

Rational Rounding Rule Literals

A RatRoundRule node represents a rational rounding rule. It is interpreted as a Muldis D sys.std.Core.Type.Cat.RatRoundRule value whose attributes are defined by the RatRoundRule_payload. A RatRoundRule_payload must be a Perl array ref with 3 elements, which correspond in order to the 3 attributes: radix (a PInt2_N), min_exp (an Int), and round_meth (a RatRoundMeth). Each of radix and min_exp must qualify as a valid Int_payload, and round_meth must qualify as a valid RatRoundMeth_payload.

Examples:

[ 'RatRoundRule', [10,-2,'HalfEven'] ]

[ 'RatRoundRule', [2,-7,'ToZero'] ]

Low Level Integer String Literals

A String node represents an integer string value. This node is interpreted as a Muldis D sys.std.Core.Type.Cat.String value as follows:

If the payload is a Perl array ref, then every one of its elements must constitute a valid payload for an Int node.
If the payload is a Perl hash ref, then it must have 1 element, whose key and value are designated, in order, max-col-val and main payload; the max-col-val must be a Perl string and the main payload must be a Perl array ref; every pairwise combination of the max-col-val with the elements of the main payload must, when appropriately wrapped in a Perl hash ref, must constitute a valid hash ref payload for an Int node.

Examples:

[ 'String', [80,101,114,109] ] # Unicode abstract codepoints = 'Perl' #

[ 'String', { F => ['50','65','72','6C'] } ] # same thing #

COLLECTION VALUE SELECTORS

Note that, with each of the main value selector nodes documented in this main POD section, any occurrences of child expr nodes should be read as being value nodes instead in contexts where instances of the main nodes are being composed beneath value nodes. That is, any expr node options beyond what value options exist are only valid within a depot node.

Scalar Selectors

A Scalar node represents a literal or selector invocation for a scalar subtype value. It is interpreted as a Muldis D sys.std.Core.Type.Scalar subtype value whose declared type is specified by the node's (mandatory for Scalar) type_name element and whose attributes are defined by the payload. If the payload is a Perl array ref, then it must have exactly 2 elements, that are designated possrep name and possrep attrs; if the payload is not a Perl array ref, then it is interpreted as if it was just the possrep attrs, and the possrep name was the empty string. The possrep name and possrep attrs must be as per the payload of a Name and Tuple node, respectively. The possrep attrs is interpreted specifically as attributes of the declared type's possrep which is specified by the possrep name. Each key+value pair of the possrep attrs defines a named possrep attribute of the new scalar; the pair's key and value are, respectively, a Perl character string that specifies the possrep attribute name, and an expr node that specifies the possrep attribute value.

Examples:

[ 'Scalar', 'sys.std.Core.Type.Cat.Name', { '' => 'the_thing' } ]

[ 'Scalar', 'sys.std.Core.Type.Rat', [ float => {
    mantissa => 45207196,
    radix    => 10,
    exponent => 37,
} ] ]

[ 'Scalar', 'sys.std.DateTime.Type.UTCDateTime', [ datetime => {
    year   => 2003,
    month  => 10,
    day    => 26,
    hour   => 1,
    minute => 30,
    second => 0.0,
} ] ]

[ 'Scalar', 'fed.lib.the_db.WeekDay', [ name => {
    '' => 'monday',
} ] ]

[ 'Scalar', 'fed.lib.the_db.WeekDay', [ number => {
    '' => 5,
} ] ]

[ 'Scalar', 'Int', { '' => ['Scalar','String.<42>',{}] } ]

[ 'Scalar', 'Text', [ nfd_codes => {
    '' => ['Scalar','String.<80><101><114><109>',{}]
} ] ]

Tuple Selectors

A Tuple node represents a literal or selector invocation for a tuple value. It is interpreted as a Muldis D sys.std.Core.Type.Tuple value whose attributes are defined by the payload. The payload must be just a Perl hash ref. Each key+value pair of the payload defines a named attribute of the new tuple; the pair's key and value are, respectively, a Perl character string that specifies the attribute name, and an expr node that specifies the attribute value.

Examples:

[ 'Tuple', {} ]

[ 'Tuple', 'type.tuple_from.var.fed.data.the_db.account.users', {
    login_name => 'hartmark',
    login_pass => 'letmein',
    is_special => ['Bool','True'],
} ]

[ 'Tuple', {
    name => 'Michelle',
    age  => 17,
} ]

Database Selectors

A Database node represents a literal or selector invocation for a 'database' value. It is interpreted as a Muldis D sys.std.Core.Type.Database value whose attributes are defined by the payload. The payload must be a just a Perl hash ref. Each key+value pair of the payload defines a named attribute of the new 'database'; the pair's key and value are, respectively, a Perl character string that specifies the attribute name, and an expr node that specifies the attribute value, which must be represent a relation value.

Relation Selectors

A Relation node represents a literal or selector invocation for a relation value. It is interpreted as a Muldis D sys.std.Core.Type.Relation value whose attributes and tuples are defined by the payload, which is interpreted as follows:

Iff the payload is a Perl array ref with zero elements, then it defines the only relation value having zero attributes and zero tuples.
Iff the payload is a Perl array ref with at least one element, and every element is a Perl character string (as per a valid payload for a Name node), then it defines the attribute names of a relation having zero tuples.
Iff the payload is a Perl array ref with at least one element, and every element is a Perl hash ref (as per a valid payload for a Tuple node), then each element of the payload defines a tuple of the new relation; every tuple-defining element of the payload must be of the same degree and have the same attribute names as its sibling elements; these are the degree and attribute names of the relation as a whole, which is its heading for the current purposes.
Iff the payload is a Perl array ref with exactly 2 elements, each of which is a Perl array ref, then: The new relation value's attribute names are defined by the payload's first element, which is a Perl array ref of character string (each as per a Name node payload), and the relation body's tuples' attribute values are defined by the payload's second element, which is a Perl array ref of Perl array ref of tuple attribute value defining nodes. This format is meant to be the most compact of the generic relation payload formats, as the attribute names only appear once for the relation rather than repeating for each tuple. As a trade-off, the attribute values per tuple from the payload second element must appear in the same order as their corresponding attribute names appear in the payload first element, as the names and values in the relation literal are matched up by ordinal position here.

Examples:

[ 'Relation', [] ]  # zero attrs + zero tuples #

[ 'Relation', [ 'x', 'y', 'z' ] ]  # 3 attrs + zero tuples #

[ 'Relation', [ {} ] ]  # zero attrs + 1 tuple #

[ 'Relation', [
    {
        login_name => 'hartmark',
        login_pass => 'letmein',
        is_special => ['Bool','True'],
    },
] ]  # 3 attrs + 1 tuple #

[ 'Relation', 'fed.lib.the_db.gene.Person', [ [ 'name', 'age' ] => [
    [ 'Michelle', 17 ],
] ] ]  # 2 attrs + 1 tuple #

Set Selectors

A Set node represents a literal or selector invocation for a set value. It is interpreted as a Muldis D sys.std.Core.Type.Set value whose elements are defined by the payload. The payload must be just a Perl array ref. Each element of the payload defines a unary tuple of the new set; each element is an expr node that defines the value attribute of the tuple.

Examples:

[ 'Set', 'fed.lib.the_db.account.Country_Names', [
    'Canada',
    'Spain',
    'Jordan',
    'Thailand',
] ]

[ 'Set', [
    3,
    16,
    85,
] ]

Maybe Selectors

A Maybe node represents a literal or selector invocation for a maybe value. It is interpreted as a Muldis D sys.std.Core.Type.Maybe value. If the node payload is missing or undefined, then the node is interpreted as the special value Maybe:Nothing, aka Nothing, which is the only Maybe value with zero elements. If the node payload is defined then the node is interpreted as a Single whose element is defined by the payload. The payload is an expr node that defines the value attribute of the single tuple of the new 'single'.

Examples:

[ 'Maybe', 'I know this one!' ]

[ 'Maybe', undef ]

Array Selectors

An Array node represents a literal or selector invocation for a array value. It is interpreted as a Muldis D sys.std.Core.Type.Array value whose elements are defined by the payload. The payload must be just a Perl array ref. Each element of the payload defines a binary tuple of the new sequence; the element value is an expr node that defines the value attribute of the tuple, and the element index is used as the index attribute of the tuple.

Examples:

[ 'Array', [
    'Alphonse',
    'Edward',
    'Winry',
] ]

[ 'Array', 'fed.lib.the_db.stats.Samples_By_Order', [
    57,
    45,
    63,
    61,
] ]

Bag Selectors

A Bag node represents a literal or selector invocation for a bag value. It is interpreted as a Muldis D sys.std.Core.Type.Bag value whose elements are defined by the payload. The payload is interpreted as follows:

Iff the payload is a Perl array ref with zero elements, then it defines the only bag value having zero elements. Iff the payload is an array ref with at least one element, then every one of the payload elements must be itself a Perl array ref.
Iff the payload is an array ref with at least one (array ref) element, and the first element of that element is itself an array ref, then the payload is interpreted as being of the array counted values bag format. Each element of the payload defines a binary tuple of the new bag; the element is a 2-element array ref, and those 2 elements, by index order, are an expr node that defines the value attribute of the tuple, and a valid Int node payload that defines the count attribute of the tuple; the count must be a positive integer.
Iff the payload is an array ref with at least one (array ref) element, and the first element of that element is not itself an array ref, then the payload is interpreted as being of the array repeated values bag format. Each element of the payload contributes to a binary tuple of the new bag; the element value is an expr node that defines the value attribute of the tuple. The bag has 1 tuple for every distinct (after format normalization) element value in the payload, and the count attribute of that tuple says how many instances of said element were in the payload.

Examples:

[ 'Bag', 'fed.lib.the_db.inventory.Fruit', [
    [ 'Apple'  => 500 ],
    [ 'Orange' => 300 ],
    [ 'Banana' => 400 ],
] ]

[ 'Bag', [
    'Foo',
    'Quux',
    'Foo',
    'Bar',
    'Baz',
    'Baz',
] ]

Interval Selectors

An SPInterval node represents a literal or selector invocation for a single-piece interval value. It is interpreted as a Muldis D sys.std.Core.Type.SPInterval value whose attributes are defined by the payload. The node payload must be a Perl array ref with 3 elements, which are designated in order: min, interval boundary kind, max. Each of min and max is an expr node that defines the min and max attribute value, respectively, of the new single-piece interval. The interval boundary kind is one of these 4 Perl character strings: .., ..^, ^.., ^..^; each of those strings corresponds to one of the 4 possible combinations of excludes_min and excludes_max values that the new single-piece interval can have, which in order are: [False,False], [False,True], [True,False], [True,True].

A special shorthand for an SPInterval payload also exists, which is to help with the possibly common situation where an interval is a singleton, meaning the interval has exactly 1 value; the shorthand empowers that value to be specified just once rather than twice. Iff the payload is not a Perl array ref, then the payload is treated as if it was instead the usual Perl array ref with 3 elements, whose min and max are both identical to the actual payload and whose interval boundary kind is ... For example, the payload 6 is shorthand for [6,'..',6].

An MPInterval node represents a literal or selector invocation for a multi-piece interval value. It is interpreted as a Muldis D sys.std.Core.Type.MPInterval value whose elements are defined by the payload. The payload must be just a Perl array ref. Each element of the payload must be a valid payload for an SPInterval node (that is, a Perl array ref with 3 elements et al). Each element of the payload defines a 4-ary tuple, representing a single-piece interval, of the new multi-piece interval.

Examples:

[ 'SPInterval', [1,'..',10] ]

[ 'SPInterval', [2.7,'..^',9.3] ]

[ 'SPInterval', ['a','^..','z'] ]

[ 'SPInterval', [[ 'UTCInstant', [2002,12,6] ], '^..^',
    [ 'UTCInstant', [2002,12,20] ]] ]

[ 'SPInterval', 'abc' ]  # 1 element #

[ 'MPInterval', [] ]  # zero elements #

[ 'MPInterval', [[1,'..',10]] ]  # 10 elements #

[ 'MPInterval', [[1,'..',3],6,[8,'..',9]] ]  # 6 elements #

DEPOT SPECIFICATION

A depot node has 2-3 ordered elements such that 3 elements means the depot has a normal-user-data database and 2 elements means it has just a (possibly empty) system catalog database: The first element is the Perl character string depot. Iff the depot has 3 elements then the third element specifies the normal-user-data database; it is a single-element Perl hash ref whose element's key is the Perl character string depot-data and whose element's value is a Database node. The second element specifies the system catalog database; it is a single-element Perl hash ref whose element's key is the Perl character string depot-catalog and whose element's value is either a Database node or a Perl array ref which is hereafter referred to as depot_catalog_payload. A depot_catalog_payload either has zero elements, designating an empty catalog, or all of its elements are Perl array refs (in particular, none of its elements is the Perl character string 'Database'), each of which is one of the following kinds of nodes: subdepot, material, self_local_dbvar_type.

A subdepot node has 3 ordered elements: The first element is the Perl character string subdepot. The second element is a Name_payload, which is the declared name of the subdepot within the namespace defined by its parent subdepot (or depot). The third element is a depot_catalog_payload.

A self_local_dbvar_type node has 2 ordered elements: The first element is the Perl character string self-local-dbvar-type. The second element is a PNSQNameChain_payload, which specifies what the normal-user-data database has as its declared data type.

Examples:

# A completely empty depot that doesn't have a self-local dbvar. #
[ 'depot', { 'depot-catalog' => [] } ]

# Empty depot with self-local dbvar with unrestricted allowed values. #
[ 'depot',
    { 'depot-catalog' => [
        [ 'self-local-dbvar-type', 'Database' ]
    ] },
    { 'depot-data' => [ 'Database', {} ] }
]

# A depot having just one function and no dbvar. #
[ 'depot', { 'depot-catalog' => [
    [ 'function', 'cube', [ 'Int', { topic => 'Int' }, [
        [ 'op', 'I^', [ ['$','topic'], 3 ] ]
    ] ] ]
] } ]

MATERIAL SPECIFICATION

A material node specifies a new material (routine or type) that lives in a depot or subdepot.

There are 8 main varieties of material node, each of which is a named node kind of its own: function, updater, procedure, scalar_type, tuple_type, relation_type, domain_type, subset_type.

Material Specification Common Elements

A material node has 2-3 ordered elements, such that a material that has 2 elements is an anon_material and a material with 3 elements is a named_material: The first element is material_kind. The last element is material_payload. Iff there are 3 elements then the middle element is material_declared_name.

material_kind: This is a character string of the format [<[ a..z ]>+] ** '-'; it identifies the kind of the material and is the only external meta-data of material_payload generally necessary to interpret the latter; what grammars are valid for material_payload depend just on material_kind.
material_declared_name: This is the declared name of the material within the namespace defined by its subdepot (or depot). It is explicitly specified iff the material is a named_material
material_payload: This is mandatory for all material. It specifies the entire material sans its name. Format varies with material_kind.

For material examples, see the subsequent documentation sections.

Function Specification

TODO.

Updater Specification

TODO.

Procedure Specification

TODO.

Scalar Type Specification

TODO.

Tuple Type Specification

TODO.

Relation Type Specification

TODO.

Domain Type Specification

TODO.

Subset Type Specification

TODO.

GENERIC VALUE EXPRESSIONS

An expr_name node has 2 ordered elements: The first element is the Perl character string $. The second element is a Name_payload.

A named_expr node has 3 ordered elements: The first element is the Perl character string ::=. The second element is a Name_payload and the third element is an expr node; the second element declares an explicit expression node name for the third element.

Examples:

# an expr_name node #
['$','foo_expr']

# a named_expr node #
[ '::=', 'bar_expr', [ 'func-invo', 'factorial', [['$','foo_expr']] ] ]

Generic Expression Attribute Accessors

An accessor node has 2-3 ordered elements, such that 2 elements makes it an acc_via_named and 3 elements makes it an acc_via_anon: The first element is the Perl character string $.. The last element of an acc_via_named is a PNSQNameChain_payload, which is by itself the target of the accessor (naming both the other node plus its attribute to alias). The second element of an acc_via_anon is an expr node which is the other node whose attribute is being aliased. The last element of an acc_via_anon is a nonempty NameChain_payload and names the attribute.

Examples:

# an accessor node of a named tuple-valued node #
['$.','foo_t.bar_attr']

# an accessor node of an anonymous tuple-valued node #
['$.',['func-invo','nlx.lib.tuple_res_func',[['$','arg']]],'quux_attr']

Generic Function Invocation Expressions

A func_invo node has 2-4 ordered elements: The first element is the Perl character string func-invo. The second element is a PNSQNameChain_payload, which names the function to invoke. The last 1-2 elements provide arguments to the function invocation; either or both or none of an Array_payload element and a Tuple_payload element may be given. The Array_payload 3rd/4th element is for any anonymous (and ordered if multiple exist) arguments, and the Tuple_payload 3rd/4th element is for any named arguments; each Array_payload element or Tuple_payload element value is an expr node which is the argument value.

Examples:

# zero params #
[ 'func-invo', 'Nothing' ]

# single mandatory param #
[ 'func-invo', 'Integer.median',
    [ [ 'Bag', [ 22, 20, 21, 20, 21, 21, 23 ] ] ] ]

# single mandatory param #
[ 'func-invo', 'factorial', { topic => 5 } ]

# two mandatory params #
[ 'func-invo', 'Rational.quotient',
    { dividend => 43.7, divisor => 16.9 } ]

# one mandatory 'topic' param, two optional #
[ 'func-invo', 'nlx.lib.barfunc', [ ['$','mand_arg'] ],
    { oa1 => ['$','opt_arg1'], oa2 => ['$','opt_arg2'] } ]

# a user-defined function #
[ 'func-invo', 'nlx.lib.foodb.bazfunc',
    { a1 => 52, a2 => 'hello world' } ]

# two params named 'topic' and 'other' #
[ 'func-invo', 'is_identical', [ ['$','foo'], ['$','bar'] ] ]

# invoke the lexically innermost routine with 2 args #
[ 'func-invo', 'rtn', [ ['$','x'], ['$','y'] ] ]

Generic If-Else Expressions

An if_else_expr node has 2-3 ordered elements: The first element is either of the 2 Perl character strings if-else-expr and ??!!. The optional second element is if_then, a Perl array ref with 0..N elements, each of those being a 2-element Perl array ref, where each element is an expr node; the first element is an if condition expression, and the second element is the associated then result expression. The 3rd/last element of an if_else_expr node is else result expression, which is an expr node.

Examples:

[ 'if-else-expr',
    [
        [[ 'op', '>', [['$','foo'], 5] ] => ['$','bar']],
    ],
    ['$','baz']
]

[ 'if-else-expr',
    [
        [[ 'op', 'is-empty', [['$','ary']] ] => ['$','empty_result']],
    ],
    [ 'op', '.[]', [['$','ary'], 0] ]
]

[ 'op', 'T~', ['My answer is: ',
    [ '??!!', [ [['$','maybe'] => 'yes'] ], 'no' ]] ]

Generic Given-When-Default Expressions

A given_when_def_expr node has 3-4 ordered elements: The first element is the Perl character string given-when-def-expr. The second element is an expr node which is the given common comparand. The optional third element is when_then, a Perl array ref with 0..N elements, each of those being a 2-element Perl array ref, where each element is an expr node; the first element is a when comparand, and the second element is the associated then result expression. The 4th/last element of a given_when_def_expr node is default result expression, which is an expr node.

Examples:

[ 'given-when-def-expr',
    ['$','digit'],
    [
        [ 'T' => 10 ],
        [ 'E' => 11 ],
    ],
    ['$','digit'],
]

Library Entity Reference Selector

TODO: REWRITE THIS DOCUMENTATION SECTION!

Examples:

['func-ref','nlx.lib.filter']

['upd-ref','nlx.lib.swap']

['proc-ref','nlx.lib.try_block']

['type-ref','nlx.lib.foo_type']

['ord-det-func-ref','nlx.lib.order_bars']

FUNCTION INVOCATION ALTERNATE SYNTAX EXPRESSIONS

A func_invo_alt_syntax node has 3-4 ordered elements: The first element is the Perl character string op. The second element is a Perl character string, hereafter referred to as op or keyword, which determines the function to invoke. The third element is (usually) a Perl array ref, hereafter referred to as main op args, which is an ordered list of 1-N mandatory inputs to the function invocation. The (optional) fourth element is a Perl hash ref, hereafter referred to as extra op args, which is a named list of optional function inputs. The number and format of elements of either main op args or extra op args varies depending on op. Note that, when a main op args would just contain a single element, such as when it is for a monadic operator, it may alternately be formatted as what is otherwise just its sole (node) element iff that node is not formatted as a Perl array ref.

Simple Commutative N-adic Infix Reduction Operators

A comm_infix_reduce_op_invo node has 2-N main op args, each of which is an expr node.

Examples:

[ 'op', 'and', [ ['Bool','True'], ['Bool','False'], ['Bool','True'] ] ]

[ 'op', 'or', [ ['Bool','True'], ['Bool','False'], ['Bool','True'] ] ]

[ 'op', 'xor', [ ['Bool','True'], ['Bool','False'], ['Bool','True'] ] ]

[ 'op', 'I+', [ 14, 3, -5 ] ]

[ 'op', 'I*', [ -6, 2, 25 ] ]

[ 'op', 'N+', [ 4.25, -0.002, 1.0 ] ]

[ 'op', 'N*', [ 69.3, [ 'Rat', [15,2,6] ], [ 'Rat', [49,23] ] ] ]

[ 'op', '∪', [ [ 'Set', [ 1, 3, 5 ] ],
    [ 'Set', [ 4, 5, 6 ] ], [ 'Set', [ 0, 9 ] ] ] ]

[ 'op', '∩', [ [ 'Set', [ 1, 3, 5, 7, 9 ] ],
    [ 'Set', [ 3, 4, 5, 6, 7, 8 ] ], [ 'Set', [ 2, 5, 9 ] ] ] ]

Simple Non-commutative N-adic Infix Reduction Operators

A noncomm_infix_reduce_op_invo node has 2-N main op args, each of which is an expr node.

Examples:

[ 'op', '[<=>]', [ ['Order','Same'],
    ['Order','Increase'], ['Order','Decrease'] ] ]

[ 'op', 'B~', [ [ 'Blob', { F => 'DEAD' } ],
    [ 'Blob', { 1 => '10001101' } ], [ 'Blob', { F => 'BEEF' } ] ] ]

[ 'op', 'T~', [ 'hello', ' ', 'world' ] ]

[ 'op', 'A~', [ [ 'Array', [ 24, 52 ] ],
    [ 'Array', [ -9 ] ], [ 'Array', [ 0, 11, 24, 7 ] ] ] ]

[ 'op', '//', [ ['$','a'], ['$','b'], 42 ] ]

[ 'op', '//d', [['$','a'],['$','b'],['type-ref','nlx.lib.foo_type']] ]

Simple Symmetric Dyadic Infix Operators

A sym_dyadic_infix_op_invo node has exactly 2 main op args, each of which is an expr node; which function arguments get which main op args isn't significant.

Examples:

[ 'op', '=', [ ['$','foo'], ['$','bar'] ] ]

[ 'op', '≠', [ ['$','foo'], ['$','bar'] ] ]

[ 'op', 'nand', [ ['Bool','False'], ['Bool','True'] ] ]

[ 'op', 'I|-|', [ 15, 17 ] ]

[ 'op', 'N|-|', [ 7.5, 9.0 ] ]

Simple Non-symmetric Dyadic Infix Operators

A nonsym_dyadic_infix_op_invo node has exactly 2 main op args, each of which is an expr node; the first and second main op args are lhs and rhs, respectively.

Examples:

[ 'op', 'isa', [ ['$','bar'], ['type-ref','nlx.lib.foo_type'] ] ]

[ 'op', '!isa', [ ['$','bar'], ['type-ref','nlx.lib.foo_type'] ] ]

[ 'op', 'as', [ ['$','scalar'], ['type-ref','Int'] ] ]

[ 'op', 'asserting', [['$','int'], [ 'op', '≠', [['$','int'], 0] ]] ]

[ 'op', 'implies', [ ['Bool','True'], ['Bool','False'] ] ]

[ 'op', 'I-', [ 34, 21 ] ]

[ 'op', 'I/', [ 5, 3 ] ]

[ 'op', '%', [ 5, 3 ] ]

[ 'op', 'I^', [ 2, 63 ] ]

[ 'op', 'N-', [ 9.2, 0.1 ] ]

[ 'op', 'N/', [[ 'Rat', {1 => '101.01'} ], [ 'Rat', {1 => '11.0'} ]] ]

[ 'op', 'Tx', [ '-', 80 ] ]

[ 'op', '∖', [ [ 'Set', [ 8, 4, 6, 7 ] ], [ 'Set', [ 9, 0, 7 ] ] ] ]

[ 'op', '÷', [ [ 'Relation', [ ['x', 'y'] => [ [5, 6], [3, 6] ] ] ],
    [ 'Relation', [ { y => 6 } ] ] ] ]

Simple Monadic Prefix Operators

A monadic_prefix_op_invo node has exactly 1 main op arg, which is an expr node.

Examples:

[ 'op', 'd', ['type-ref','nlx.lib.foo_type'] ]

[ 'op', 'not', [['Bool','True']] ]

[ 'op', 'I||', -23 ]

[ 'op', 'N||', -4.59 ]

[ 'op', 'R#', [[ 'Set', [ 5, -1, 2 ] ]] ]

[ 'op', 't', [['$','relvar']] ]

[ 'op', 'r', [['$','tupvar']] ]

[ 'op', 's', [[ 'op', 'N+',
    [[ 'op', 'v', [['$','a']] ], [ 'op', 'v', [['$','b']] ]] ]] ]

Simple Monadic Postfix Operators

A monadic_postfix_op_invo node has exactly 1 main op arg, which is an expr node.

Examples:

[ 'op', '++', 13 ]

[ 'op', '--', 4 ]

[ 'op', 'I!', 5 ]

Simple Postcircumfix Operators

A postcircumfix_op_invo node has exactly 2-3 main op args, where the first is an expr node that defines the primary input value for the operator and the other 1-2 provide attribute names that customize the operation.

Note that for the [] op, the min_index, interval_boundary_kind, max_index are collectively the 2nd main op arg which is an SPInterval node payload that defines an sp_interval_of.NNInt.

Examples:

[ 'op', '.${}', [['$','birthday'], 'date', 'day'] ]

[ 'op', '.%{}', [['$','pt'], 'city'] ]

[ 'op', '%{<-}', [['$','pt'], {pnum=>'pno', locale=>'city'}] ]

[ 'op', '@{<-}', [['$','pr'], {pnum=>'pno', locale=>'city'}] ]

[ 'op', '${}', [['$','birthday'], 'date', ['year','month']] ]

[ 'op', '%{}', [['$','pt'], ['color','city']] ]

[ 'op', '@{}', [['$','pr'], ['color','city']] ]

[ 'op', '%{}', [['$','pt'], []] ]  # null projection #

[ 'op', '@{}', [['$','pr'], []] ]  # null projection #

[ 'op', '${!}', [['$','rnd_rule'], ['round_meth']] ]  # radix,min_exp #

[ 'op', '%{!}', [['$','pt'], ['pno','pname','weight']] ]

[ 'op', '@{!}', [['$','pr'], ['pno','pname','weight']] ]

[ 'op', '%{%<-}', [['$','person'], 'name', ['fname','lname']] ]

[ 'op', '@{%<-}', [['$','people'], 'name', ['fname','lname']] ]

[ 'op', '%{%<-!}', [['$','person'],'all_but_name',['fname','lname']] ]

[ 'op', '@{%<-!}', [['$','people'],'all_but_name',['fname','lname']] ]

[ 'op', '%{<-%}', [['$','person'], ['fname','lname'], 'name'] ]

[ 'op', '@{<-%}', [['$','people'], ['fname','lname'], 'name'] ]

[ 'op', '@{@<-}', [['$','orders'], 'vendors', ['vendor']] ]

[ 'op', '@{@<-!}', [['$','orders'], 'all_but_vendors', ['vendor']] ]

[ 'op', '@{<-@}', [['$','orders'], ['vendor'], 'vendors'] ]

[ 'op', '@{#@<-!}',
    [['$','people'], 'count_per_age_ctry', ['age','ctry']] ]

[ 'op', '.[]', [['$','ary'], 3] ]

[ 'op', '[]', [['$','ary'], [10,'..',14]] ]

Rational Operators That Do Rounding

A rat_op_invo_with_round node has exactly 2-3 main op args, each of which is an expr node that defines an input value for the operator. When there are 2 main op args, the first and second args are expr and round_rule, respectively. When there are 3 main op args, the first, second and third args are lhs, rhs and round_rule, respectively.

Examples:

[ 'op', 'round', [ ['$','foo'],
    [ 'RatRoundRule', [10,-2,'HalfEven'] ] ] ]

[ 'op', 'N^', [ 2.0, 0.5, [ 'RatRoundRule', [2,-7,'ToZero'] ] ] ]

[ 'op', 'log', [ 309.1, 5.4, [ 'RatRoundRule', [10,-4,'HalfUp'] ] ] ]

[ 'op', 'e^', [ 6.3, [ 'RatRoundRule', [10,-6,'ToCeiling'] ] ] ]

[ 'op', 'log-e', [ 17.0, [ 'RatRoundRule', [3,-5,'ToFloor'] ] ] ]

Order Comparison Operators

An ord_compare_op_invo node has exactly 2 or 3 or 2-N main op args, depending on the op, each of which is an expr node. When the op requires exactly 2 main op args, the first and second args are lhs and rhs, respectively. When the op requires exactly 2 main op args, the first, second and third args are min, expr, and max, respectively. When the op is N-adic, requiring 2-N main op args, then the order of the main op args isn't significant. Details on the extra op args are pending.

Examples (for now sans any use of extra op args, which are atypical):

[ 'op', '<=>', [ ['$','foo'], ['$','bar'] ] ]

[ 'op', 'min', [ ['$','a'], ['$','b'], ['$','c'] ] ]

[ 'op', 'max', [ ['$','a'], ['$','b'], ['$','c'] ] ]

[ 'op', '<', [ ['$','foo'], ['$','bar'] ] ]

[ 'op', '>', [ ['$','foo'], ['$','bar'] ] ]

[ 'op', '≤', [ ['$','foo'], ['$','bar'] ] ]

[ 'op', '≥', [ ['$','foo'], ['$','bar'] ] ]

[ 'op', 'I∈', [ ['$','a'], [ 'SPInterval', [1,'..',5] ] ] ]

[ 'op', '≤≤', [ ['$','min'], ['$','foo'], ['$','max'] ] ]

[ 'op', '≤<', [ ['$','min'], ['$','foo'], ['$','max'] ] ]

[ 'op', '!<≤', [ ['$','min'], ['$','foo'], ['$','max'] ] ]

[ 'op', '!<<', [ ['$','min'], ['$','foo'], ['$','max'] ] ]

DATE-TIME EXTENSION OPAQUE VALUE LITERALS

When this extension is active, there exist 3 additional varieties of value node: UTCInstant, FloatInstant, UTCDuration. Also, between these 3 varieties, these 9 additional values are allowed for value's value_kind attribute: UTC[Instant|DateTime|Date|Time], Float[Instant|DateTime|Date|Time], UTCDuration. For all of these varieties, the value_kind may not be omitted.

Date and Time Literals

A UTCInstant node represents an "instant"/"datetime" value that is affiliated with the UTC time-zone. This node is interpreted as a Muldis D sys.std.DateTime.Type.UTCInstant value whose instant possrep attribute values are defined as follows:

If the payload is a Perl array ref, then it must have 6 elements, where each element may be either undefined or defined; or if fewer than 6 elements are provided, the array ref will be implicitly extended to 6, filling with undefs. The 6 payload elements correspond in order, from the lowest to the highest indexed, to the 6 attributes: year, month, day, hour, minute, second. For each payload element that Perl considers undefined or defined, the corresponding attribute has the Nothing or a Single value, respectively. For each of the first 5 elements, when it is defined, it must qualify as a valid payload for an Int node; for the 6th element, when it is defined, it must qualify as a valid payload for a Rat node.

A defined year may be any integer, each of [month, day] must be a positive integer, each of [hour, minute] must be a non-negative integer, and second must be a non-negative rational number. If all 6 attributes are defined, then the new UTCInstant value is also a UTCDateTime; if just the first 3 or last 3 are defined, then the value is not a UTCDateTime but rather a UTCDate or UTCTime, respectively; if any other combination of attributes are defined, then the value is just a UTCInstant and not of any of the other 3 subtypes.
If the payload is a Perl hash ref, then it must have 1 element, whose key and value are designated, in order, max-col-val and main payload; the max-col-val must be a Perl string and the main payload must be a Perl array ref as per the payload of the previous bullet point but that none of the 6 elements is a Perl hash ref. Each of the 6 main payload elements, when defined, is further interpreted according to the max-col-val, in the same manner as how an Int or Rat node's hash ref payload's element's value is interpreted. The interpretation of this payload is the same as for the Perl array ref payload.

A FloatInstant node represents an "instant"/"datetime" value that is "floating" / not affiliated with any time-zone. This node is interpreted as a Muldis D sys.std.DateTime.Type.FloatInstant value in an identical fashion to how a UTCInstant node is interpreted, whose format it completely shares. Likewise regarding Float[DateTime|Date|Time].

A UTCDuration node represents a duration value, an amount of time, which is not fixed to any instant in time. This node is interpreted as a Muldis D sys.std.DateTime.Type.UTCDuration value whose duration possrep attribute values are defined as follows:

If the payload is a Perl array ref, then it must have 6 elements, where each element may be either undefined or defined; or if fewer than 6 elements are provided, the array ref will be implicitly extended to 6, filling with undefs. The 6 payload elements correspond in order, from the lowest to the highest indexed, to the 6 attributes: years, months, days, hours, minutes, seconds. For each payload element that Perl considers undefined or defined, the corresponding attribute has the Nothing or a Single value, respectively. For each of the first 5 elements, when it is defined, it must qualify as a valid payload for an Int node; for the 6th element, when it is defined, it must qualify as a valid payload for a Rat node.

A defined [years, months, days, hours, minutes] may be any integer, and seconds may be any rational number. Currently, UTCDuration has no system-defined subtypes, but that may change later.
If the payload is a Perl hash ref, then it must have 1 element, whose key and value are designated, in order, max-col-val and main payload; the max-col-val must be a Perl string and the main payload must be a Perl array ref as per the payload of the previous bullet point but that none of the 6 elements is a Perl hash ref. Each of the 6 main payload elements, when defined, is further interpreted according to the max-col-val, in the same manner as how an Int or Rat node's hash ref payload's element's value is interpreted. The interpretation of this payload is the same as for the Perl array ref payload.

Examples:

[ 'UTCInstant', [1964,10,16,16,12,47.5] ] # a UTCDateTime #

[ 'UTCInstant', [2002,12,6] ] # a UTCDate #

[ 'UTCInstant', [undef,undef,undef,14,2,29.0] ] # a UTCTime #

[ 'FloatInstant', [2003,4,5,2] ] # min,sec unknown or N/A #

[ 'FloatInstant', [1407] ] # just know its sometime in 1407 #

[ 'UTCDuration', [3,5,1,6,15,45.000012] ]

AUTHOR

Darren Duncan (darren@DarrenDuncan.net)

LICENSE AND COPYRIGHT

This file is part of the formal specification of the Muldis D language.

See the LICENSE AND COPYRIGHT of Muldis::D for details.

TRADEMARK POLICY

The TRADEMARK POLICY in Muldis::D applies to this file too.

ACKNOWLEDGEMENTS

The ACKNOWLEDGEMENTS in Muldis::D apply to this file too.

To install Muldis::D, copy and paste the appropriate command in to your terminal.

cpanm

cpanm Muldis::D

CPAN shell

perl -MCPAN -e shell
install Muldis::D

For more information on module installation, please visit the detailed CPAN module installation guide.

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NAME

VERSION

PREFACE

DESCRIPTION

GENERAL STRUCTURE

START

LANGUAGE NAME

CATALOG ABSTRACTION LEVELS

the_floor

code_as_data

plain_rtn_inv

rtn_inv_alt_syn

STANDARD SYNTAX EXTENSIONS

date_time

VALUE LITERALS AND SELECTORS

Value Literal Common Elements

OPAQUE VALUE LITERALS

Boolean Literals

Order-Determination Literals

Rational Rounding Method Literals

General Purpose Integer Numeric Literals

General Purpose Rational Numeric Literals

General Purpose Binary String Literals

General Purpose Character String Literals

DBMS Entity Name Literals

Code Comment Literals

TAI Temporal Literals

Rational Rounding Rule Literals

Low Level Integer String Literals

COLLECTION VALUE SELECTORS

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FUNCTION INVOCATION ALTERNATE SYNTAX EXPRESSIONS

Simple Commutative N-adic Infix Reduction Operators

Simple Non-commutative N-adic Infix Reduction Operators

Simple Symmetric Dyadic Infix Operators

Simple Non-symmetric Dyadic Infix Operators

Simple Monadic Prefix Operators

Simple Monadic Postfix Operators

Simple Postcircumfix Operators

Rational Operators That Do Rounding

Order Comparison Operators

DATE-TIME EXTENSION OPAQUE VALUE LITERALS

Date and Time Literals

SEE ALSO

AUTHOR

LICENSE AND COPYRIGHT

TRADEMARK POLICY

ACKNOWLEDGEMENTS

Module Install Instructions