---

Abstract

Introduction

Most programming languages use similar positional grammatical cues. The operation $maximum = $next is very different in meaning from $next = $maximum. Likewise, the function call push @my_assets, @your_money is not the same as push @your_money, @my_assets.

Generally speaking, older natural languages have richer lexical structures (such as inflexions for noun number and case) and therefore rely less on word order. For example, in Latin the statements Puer dedit cani escam and Escam dedit puer cani both mean ``The boy gave the dog the food''. Indeed, the more usual word order would be reverse Polish, with the verb coming last: Puer cani escam dedit.

This flexibility is possible because Latin uses inflexion, not position, to denote lexical roles. The lack of a suffix denotes that the boy (puer) is the subject; the -i ending indicates that the dog (cani) is the indirect object; whilst the -am ending indicates that the food (escam) is the direct object.

To say ``The food gave the boy the dog'', one might write: Puero canem esca dedit. Here, the -o ending denotes that the boy is now the indirect object, the -em ending indicates that the dog has become the direct object, whilst the -a ending indicates that the food is the subject.
 
 

A less positional programming language

Indeed, there is no reason why certain built-in functions, such as bless, or the block form of map, or even push could not allow their arguments to be specified in any order, at least in cases where the prefixes (or the lack thereof) make the roles of each argument unambiguous:

        my $obj = bless 'Classname', \%obj;

        @squares = map @numbers {$_**2};

        push ('Moe', 'Larry', 'Curly') => @stooges;

        @squares = @numbers map {$_**2};

        ('Moe', 'Larry', 'Curly') => @stooges push;

        if ($next > $max) { $max = $next }

        # ...is the same as...

        $max = $next if $next > $max;

Semantic roles

In both cases, the operand or argument to be modified is denoted positionally -- it is always the left operand or the first argument. Furthermore this argument is always ``implicitly enreferenced'', as if it had a \$ or \@ prototype.

Thus, in Perl, operands and arguments have one of two semantic roles: target or data. A target is passed by reference and is modified during the evaluation of an operation or function. Data are passed by value (though that value itself may be a reference) and they control or ``fuel'' the modification of the target.

In this model, it is possible to recast almost all built-in Perl functions and operations as procedures of exactly two arguments: a single reference (the target) and a single list (the data):

        _sysopen( -target=>\*FILE, -data=>[$filename,$mode,$perms] );

        _push( -target=>\@stooges, -data=>['Moe', 'Larry', 'Curly'] );

        _pop( -target=>\@stack, -data=>[] );
        
        _assign( -target=>\$max, -data=>[$nextval] )
                if _num_less_than( -target=>undef, -data=>[$max, $nextval] );

        _assign( -target=>\$now, -data=>[ _time(-target=>undef, -data=>[]) ]);

Mapping the model to Latin

Consider the assignment of a list to an array:

        @gunslingers = ( @good, @bad, $Ugly );

        _assign( -target=>\@gunslingers, -data=>[@good, @bad, $Ugly] );

        Assign gunslingers goodies and baddies and Mr Ugly.

The English version also uses a plural inflexion on ``goodies'' and ``baddies'', much in the same way that Perl uses the @ prefix to indicate the multiplicity of the objects involved.

In Latin, the same instruction would be (loosely) rendered:

        Bonos tum malos tum Foedum pugnatoribus da.

Unlike the English ``-s'' ending, the various Latin suffixes (-os, -um, -ibus) specify both the number and the role (or ``case'') of the nouns they inflect. This means that the positions of the various objects, and indeed of the verb itself, do not matter. The same sentence could equally well be written:

        Pugnatoribus da bonos tum malos tum Foedum.

        Da bonos tum malos tum Foedum pugnatoribus.

        _assign( -target=>\@gunslingers, -data=>[@good, @bad, $Ugly] );

        @gunslingers = ( @good, @bad, $Ugly );

Lingua::Romana::Perligata

Variables

Hashes represent something of a difficulty in Perligata, as Latin lacks an obvious way of distinguishing these ``plural'' variables from arrays. The solution that has been adopted is to depart from the second declension and represent hashes as masculine plural nouns of the fourth declension.

Hence, the type and role of all types variables are specified by their number and case, as indicated in Table 1.

When elements of arrays and hashes are referred to directly in Perl, the prefix of the container changes from @ or % to $. So it should not be surprising that Perligata also makes use of a different inflexion to distinguish these cases.

Indexing operations such as $array[$elem] or $hash{$key} might be translated as ``elem of array'' or ``key of hash''. This suggests that when arrays or hashes are indexed, their names should be rendered in the genitive (or possessive) case. Multi-level indexing operations ($array[$row][$column]) mean ``column of row of array'', and hence the first indexing variable must also be rendered in the genitive. Table 1 also summarizes this role.

In other words, scalars are always singular nouns, arrays and hashes are always plural (but of different declensions), and the case of the noun specifies its role: accusative for data, dative for target, genitive when being indexed.

The common punctuation variables $_ and @_ are special cases. $_ is often the value under implicit consideration (e.g. in pattern matches, or for loops) and so it is rendered as ``this thing'': hoc in the data role, huic in the target role, huius when indexed.

Similarly, @_ is implicitly the list of things passed into a subroutine, and so is rendered as ``these things'': haec in the data role, his in the target role, horum when indexed.

Other punctuation variables take the Latin forms of their English.pm equivalents (see Appendix A), often with a large measure of poetic licence. For example, in Perligata, $/ is rendered as ianitorem or ``gatekeeper''.

The ``numeral'' variables -- $1, $2, etc. -- are rendered as synthetic compounds: parprimum (``the equal of the first''), parsecundum (``the equal of the second''), etc. When indexed, they take their genitive forms: parprimi, parsecundi, etc. Since they cannot be directly modified as the target of an action, they have no dative forms.
 
 

my, our, and local

        meo varo haec da.                # my $var = @_;
        meis varo haec da.               # my ($var) = @_
        meis varis haec da.              # my @var = @_;

The Perl local modifier is loco or locis in Perligata:

        loco varo haec da.               # local $var = @_;
        locis varo haec da.              # local ($var) = @_
        locis varis haec da.             # local @var = @_;

Subroutines

User-defined subroutines are the simplest group. To avoid ambiguity, they are all treated as verbs of the third conjugation. Table 2 illustrates the various usages for a user-defined subroutine count().

The use of the infinitive as a subroutine definition is obvious: accipere would tell Perligata how ``to accept''; spernere, how ``to reject''. So countere specifies how ``to count''.

The use of the imperative for void context is also straightforward: accipe commands Perligata to ``accept!'', sperne tells it to ``reject!'', and counte bids it ``count!''. In each case, an instruction is being given (and in a void context too, so no backchat is expected).

Handling scalar and list contexts is a little more challenging. The corresponding Latin must still have verbal properties, since an action is being performed upon objects. But it must also have the characteristics of a noun, since the result of the call will itself be used as the object (i.e. target or data) of some other verb. Fortunately, Latin has a rich assortment of verbal nouns -- far more than English -- that could fill this role.

Since it is the result of the subroutine call that is of interest here, the best solution was to use the -ementum suffix, which specifies the (singular, accusative) outcome of an action. This corresponds to the result of a subroutine called in a scalar context and used as data. For a list data context, the plural suffix -ementa is used, and for targets, the dative forms are used: -emento and -ementis. Note that these endings are completely consistent with those in Table 1.
 
 

Built-in functions and operators

However, Latin already has a perfectly good verb with the same meaning as shift: decapitare (``to behead''). Unfortunately, this verb is of the first conjugation, not the second, and hence has the imperative form decapita, which makes it look like a Perligata array in a data role.

Orthogonality has never been Perl's highest design criterion, so Perligata follows suit by eschewing bland consistency in favour of aesthetics. All Perligata keywords -- including function and operator names -- are therefore specified as correct Latin verbs, of whatever conjugation is required. Table 3 shows a selection of these, whilst Appendix A contains the full list of Perligata keywords.

Note, however, that consistency has not been entirely forsaken. The back-formations of inflexions for scalar and list context are entirely regular, and consistent with those for user-defined subroutines (Table 2).

A few Perl built-in functions -- pos, substr, keys -- can be used as lvalues. That is, they can be the target of some other action (typically of an assignment). In Perligata such cases are written in the dative singular (since the lvalues are always scalar). Note too that, because an assignment to an lvalue function modifies its first argument, that argument must be a target too, and hence must be written in the dative as well.

Thus:

        nexto stringum reperimentum da.     # $next = pos $string;
        nextum stringo reperimento da.      # pos $string = $next;

        inserto stringum tum unum tum duo excerpementum da.
                                    # $insert = substr($string,1,2);
        insertum stringo unum tum duo excerpemento da.
                                    # substr($string,1,2) = $insert;

        keyis hashus nominamentum da        # @keys = keys %hash;
        keya hashibus nominamento da        # keys %hash = @keys;

Blocks and control structures

Some such mechanism would be an obvious choice for denoting Perligata code blocks, but there is a more aesthetically pleasing solution. Perl's block delimiters ({..}) have two particularly desirable properties: they are individually short, and collectively symmetrical. It was considered important to retain those characteristics in Perligata.

In Latin, the word sic has a sense that means ``as follows''. Happily, its contranym, cis, has the meaning (among others) ``to here''. The allure of this kind of wordplay being impossible to resist, Perligata delimits blocks of statements with these two words. For example:

        sic                                     # {
            loco ianitori.                     #   local $/;
            dato fonti perlegementum da.        #   $data = <DATA>;
        cis                                     # }

The trailing fac is the imperative form of facere (``to do'') and is used as a delimiter on the control statement's condition.

The choice of dum and donec is completely arbitrary, since Latin does not distinguish ``while'' and ``until'' as abstractions in the way English does. Dum and donec each mean both ``while'' and ``until'', and Latin relies on context (i.e. semantics) to distinguish them. This is impractical for Perligata, so it always treats dum as while and donec as until. This choice was made in order to favour the shorter term for the more common type of loop.

The choice of confectus for continue seeks to convey the function of the control structure, not the literal meaning of the English word. That is, a continue block specifies how to complete (conficere) an iteration.

Perligata only supports the pure iterative form of for(each), not the C-like three-part syntax. Because:

        foreach $var (@list)...

        per quisque varum in listis...

Miscellaneous other features

Numbers

When a numeric literal is used in an indexing operation, it must be an ordinal (``first of'', ``second of'', etc). The first ten ordinals are named: primum, secundum, tertium, quartum, quintum, sextum, septimum, octavum, nonum, decimum (in the accusative, of course, since they are always data). Ordinals greater than ten are represented by their corresponding numeral with the suffix -imum: XVimum (``15th''), XLIIimum (``42nd''), etc. By analogy, ordinal zero is rendered by the invented form nullimum.

In a multi-level indexing operation, ordinals may need to be specified in the genitive: nulli, primi, secundi, tertii, quarti...XVimi...XLIIimi, etc.

For example:

        $unimatrix[1][3][9][7];

        septimum noni tertii primi unimatrixorum
        # seventh of ninth of third of first of unimatrix

Floating point numbers are expressed in Perligata as Latin fractions:

        unum quartum                    # 0.25
        MMMCXLI Mimum                 # 3.141

Strings

        print STDOUT 'Enter next word:';

        Enter tum next tum word inquementum tum biguttam egresso scribe.

Perligata does not provide an interpolated quotation mechanism. Instead, variables must be concatenated into a string. So:

        print STDERR "You entered $word\n";

        You tum entered inquementum tum wordum tum novumversum oraculo scribe.

References

For example:

        val inquementum datuum ad datum da.       # $dat{val} = \$data;
        arg inquementum datuum ad arga da.        # $dat{arg} = \@arg;
        act inquementum datuum functorem da.      # $dat{act} = \&func;

        anonymo da factorem sic haec mori cis.    # $anon = sub { die @_ };

        anonymume nos tum morituri inquementum.   # &$anon('Nos morituri');

In the few cases where a subroutine reference can be the target of an action, the dative suffix (-tori) is used instead:

        benedictum functori classum.              # bless \&func, $class;
        benedictum factori sic mori cis classum.  # bless sub{die}, $class;

Boolean logic

	resulto damentum foundum atque defum.    # $result = $found && $def;
        resulto damentum foundum defumque.       # $result = $found and $def;
        resulto damentum foundum vel defum.      # $result = $found || $def;
        resulto damentum foundum defumve.        # $result = $found or $def;

        $result = $val or max($1,$2);

        resulto damentum valum parprimumve tum parsecundum maxementum.

        si valus praecedit datum...              # if $val < $dat...
        si praecedit datum valus...              # if $val < $dat...
        si datum valus praecedit...              # if $val < $dat...

To avoid these problems, Perligata represents the equality and simple inequality operators by three pairs of verbal nouns as described in Table 5.

Each operator takes two data arguments, which it compares:

        si valum tum datum aequalitam...               # if $val == $dat...
        si valum praestantias datum...                 # if $val lt $dat...
        digere sic aum comparitiam bum cis lista.      # sort {$a<=>$b} @list;

The effects of the other comparison operators -- >, <=, !=, ne, ge, etc. -- are all achieved by appropriate ordering of the two arguments and combination with the the logical negation operator non:

        si valum datum non aequalitam...         # if $val != $dat...
        si datum praestantiam valum...           # if $val > $dat...
        si valum non praestantias datum...       # if $val ge $dat...

Packages and classes

To explicitly specify a variable or subroutine as belonging to a package, the preposition intra (``within'') is used. To call a subroutine as a method of a particular package (or of an object), the preposition apud (``of the house of'') is used.

The Perl bless function is benedice in Perligata, but almost invariably used in the scalar data role: benedictum.

Thus:

        domus Specimen.                        # package Specimen;

        newere                                      # sub new
        sic                                         # {
            meis datibus.                           #   my %data;
            counto intra Specimen
                postincresce.                       #   $Specimen::count++;
            datibus nullum horum benedictum.        #   bless \%data, $_[0];
        cis                                         # }

        printere                                    # sub print
        sic                                         # {
            modus tum indefinitus inquementum mori. #   die 'method undefined';
        cis                                         # }

        domus princeps.                             # package main;

        meo objecto da                              # my $object =
                newementum apud Specimen.      #       Specimen->new;

        printe apud objectum;                       # $object->print;

Putting it all together -- a Greek algorithm in Latin

        #! /usr/local/bin/perl -w

        use Lingua::Romana::Perligata;

        maximum inquementum tum biguttam egresso scribe.
        meo maximo vestibulo perlegamentum da.
        da duo tum maximum conscribementa meis listis.

        dum listis decapitamentum damentum nexto
            fac sic
                nextum tum novumversum scribe egresso.
                lista sic hoc recidementum nextum cis vannementa da listis.
            cis.

        print STDOUT 'maximum:';                  
        my $maxim = <STDIN>;                     
        my (@list) = (2..$maxim);

        while ($next = shift @list)             
            {
                print STDOUT $next, "\n";
                @list = grep {$_ % $next} @list; 
            }

The implementation of the Lingua::Romana::Perligata module

Filtering

Tokenization

The tokenizer is very simple: it just splits the source on whitespace or on a period, and then classifies each word in the resulting list by matching it against a series of increasingly general patterns. Keywords are tested first, followed by numbers and numerals, punctuation variables, user-defined functions in scalar and list contexts, user-defined subroutines in void contexts, variables in a target role (i.e. datives), and finally variables in a data role (accusatives),

As each word is classified, it is converted to an object of the corresponding token type -- Keyword, Number, Var, Sub, etc. Each object stores the original word and its corresponding Perl construct. For example, the sequence dum maxo maxa maxamentum damentum would yield a list equivalent to:

        (
            bless({ raw=>'dum',        perl=>'while' }, 'Conditional'     ),
            bless({ raw=>'maxo',       perl=>'$max'  }, 'Noun_Dative'     ),
            bless({ raw=>'maxa',       perl=>'@max'  }, 'Noun_Accusative' ),
            bless({ raw=>'maxamentum', perl=>'&max'  }, 'Verb_Resultative'),
            bless({ raw=>'da',         perl=>'='     }, 'Verb_Imperative  ),
        )

Parsing

For example, to write a rule that matches Perligata subroutine calls, the following is required:

        Action: Dative AccusativeList Verb
              | AccusativeList Dative Verb
              | AccusativeList Verb Dative
              | Dative Verb AccusativeList
              | Verb Dative AccusativeList
              | Verb AccusativeList Dative
              | Accusative Verb Accusative
              | Dative Verb
              | AccusativeList Verb
              | Verb Dative
              | Verb AccusativeList
              | Verb

This produces a left-recursive grammar with an unusually large number of shift/reduce and reduce/reduce ambiguities (over 100 of each), which makes the grammar very sensitive to subrule precedence and to the ordering of productions within each rule. Appendix B shows the full grammar.

To cope efficiently with these constraints, an LALR(1) parser was built using François Désarménien's excellent Parse::Yapp module.
 
 

Translation and execution

        bless( {
            condition =>
              bless( {
                 target =>
                    bless( { raw => 'maxo', perl => '$max' }, 'Var_Target'),
                 data =>
                    bless( {
                       raw  => 'maxamentum', perl => '&max',
                       data => [
                          bless( { raw=>'maxa', perl=>'@max'  }, 'Var_Data'),
                       ],
                    }, 'SubCall'),
                }, 'Assignment'),
             block =>
                undef,
        }, 'WhileLoop');

Conclusion

The use of inflexion to denote semantic roles in a programming language offers an interesting variation from the ubiquity of positional syntax, replacing the requirement to recall syntactic rules with the requirement to remember suffixes. Which of these two tasks is easier will probably vary from programmer to programmer.

With the release of this module on the CPAN, the author looks forward to the advent of truly epic Perl poetry.
 
 

Acknowledgements

Appendix A: Perligata dictionary

In each of the following tables, the three columns are always the same: ``Perl construct'', ``Perligata equivalent'', ``Literal meaning of Perligata equivalent''.

Generally, only the accusative form is shown for nouns and adjectives, and only the imperative for verbs.
 
 
 
 

Table A1: Values and variables
 

Table A2: Quotelike operators
 

Table A3: Mathematical operators and functions
 

Table A4: Logical and comparison operators
 

Table A5: Strings
 

Table A6: Scalars, arrays, and hashes
 

Table A7: I/O related
 

Table A8: Control
 

Table A9: Packages, classes, and modules
 

Table A10: System and filesystem interaction
 

Table A11: Miscellaneous operators
 

Appendix B: Perligata grammar

Script:         Statement(s)

Statement       ( Conditional | Imperative | Data | Target ) '.'

Conditional:      Control Block
                | Imperative Control

Control:          'dum'   Data  'fac'                      # while
                | 'donec' Data  'fac'                      # until
                | 'si'    Data  'fac'                      # if
                | 'nisi'  Data  'fac'                      # unless
                | /per (quisque)?/ NOUN_ACCUSATIVE(?)
                                   'in' Target 'fac'       # foreach A (B)

Block:            'sic'  Script  'cis'

Imperative:       Data Verb Data
                | Target Datalist Verb
                | Datalist Target Verb
                | Datalist Verb Target(?)
                | Target Verb Datalist(?)
                | Verb Target Datalist(?)
                | Verb Datalist Target(?)
                | Verb

Target:           NOUN_DATIVE
                | POSSESSIVE  NOUN_DATIVE               # my $A, local @B, etc.
                | Block
                | Data  Resultative_dative  Data
                | Target  Datalist  Resultative_dative
                | Datalist  Target  Resultative_dative
                | Datalist  Resultative_dative  Target(?)
                | Target  Resultative_dative  Datalist(?)
                | Resultative_dative  Target  Datalist(?)
                | Resultative_dative  Datalist(?)  Target(?)
                | Target  'intra'  Accusative           # B::A
                | Target  'apud'  Dative                # B->A
                | Target NOUN_GENITIVE                  # B[A]
                | 'factori' Block                       # sub {...}

Accusative:       NOUN_ACCUSATIVE
                | 'ad'  Accusative                      # \A
                | Accusative  'intra'  Accusative       # B::A
                | Accusative  'apud'  Accusative        # B->A
                | Accusative  NOUN_GENITIVE             # B[A]
                | 'factorem' Block                      # sub {...}

Data:             Accusative
                | 'nega'  Data                          # -A
                | 'non'  Data                           # !A
                | Data  Resultative_accusative  Data
                | Target  Datalist  Resultative_accusative
                | Datalist  Target  Resultative_accusative
                | Datalist  Resultative_accusative  Target(?)
                | Target  Resultative_accusative  Datalist(?)
                | Resultative_accusative  Target  Datalist(?)
                | Resultative_accusative  Datalist(?)  Target(?)

Verb:             VERB
                | Verb  'intra'  Accusative             # B::A()
                | Verb  'apud'  Dative                  # B->A()

Resultative_dative:              
                  RESULTATIVE_DATIVE
                | Resultative_dative  'intra'  Accusative       
                | Resultative_dative  'apud'  Dative

Resultative_accusative:          
                  RESULTATIVE_DATIVE
                | Resultative_accusative  'intra'  Accusative   
                | Resultative_accusative  'apud'  Dative        

Datalist:         Datalist  'tum'  Data
                | Data