title: The Maat Programming Language Specification author: Kueppo Tcheukam J. W.

email: tcheukueppo@yandex.com

Maat

Maat is a powerful, efficient, lightweight, embeddable multi-paradigm general purpose programming language that empowers programmers to easily build fast and scalable applications.

Key features of the Maat programming language:

Functional Programing
Object Oriented Programming
Multiple Dispatching
Closures
Concurrency with Works and Maatines
Traits
Lazy Evaluation
Regular Expressions using PCRE2
Coroutines
Generator Functions
Full Unicode support
Phasers

This is the specification of the Maat programming language, it is written as a guidance for its implementation.

NB: Take note of the following conventions when reading syntax definitions

[ X ] implies X is optional

< X > for grouping X

| implies alternation, for example A | B signifies either A or B

* implies the previous entity be it optional or not, can occur 0 or many times

* implies the previous entity be it optional or not, can occur 1 or many times

Words written in capital letter are self-documentary, for example CODE

Lowercase words are keywords, for example fun

Operators

This is the list of all operators supported by the Maat programming language, you are not required to master everything now as they are meticulously documented

Lonely operator

…, ...: to specify unimplemented code

p: postfix, i: infix, b: prefix

Basic unary operators

++: (p,b) incrementation operator
--: (p,b) decrementation operator
-: (b) negation operator
+: (b) positive operator, result of the evaluation is equal to the operand
~: (b) binary complement
… or ...: (b) destructor/accumulator operator
^: (p) Range operator, ^5 returns a Range object, i.e Range.new(0, 5)
√: (p) sqaure root operator
⁰ ¹ ² ³ ⁴ ⁵ ⁶ ⁷ ⁸ ⁹: (b) power operators
Σ: (p) summation operator
Π: (p) product operator

Named unary operators

defined: (b) check if a variable is nil
sleep: (b) sleep the current Maatine for a given amount of time
return: (b) return from a function
assert: (b) test an assertion
assert_eq: (b) equality test assertion
exit: (b) exit program with given exit code

Named list operators

say: (b) print to the standard output with a trailing new line
print: (b) print without a new line
printf: (b) print formatted string
sprintf: (b) sprintf, return formatted string
join: (b) function version of .join method of the Array type
map: (b) function version of .map method of the Array type
lmap: (b) function version of .lmap method of the Array type
grep: (b) function version of .grep method of the Array type
run: (b) run the passed as argument commands with their parameters on a new shell
die: (b) raise an exception and exit program if there is no handler
warn: (b) warn by sending a message to the stderr

Named binary operators

isa: (i) o isa str returns true if o is an object instance of class str or of a class which is subclass to str
minmax: (i) returns in an array the min and the max of its left and right operand

Binary operators for maat objects

=: (i) assignment operator
.: (i) method call operator on objects and classes
.^: (i) method call operator for meta-programming
,, =>: (i,i) comma and key-value separator infix operator
!: (p) negation operator ex: !true == false
//: (i) a variant of the || operator that tests for definedness, a // b, returns a if it isn't nil otherwise b
== / ⩵, != / ≠, >, >= / ≥, <, <= / ≤: (i) basic infix operators
+, -, / / ÷, *, %, .. / ``: (i) add, sub, div, mul, remainder and range operator
+=, /= / ÷=, -=, //=, *=, %=: (i) X op= Y same as X = X op Y
<<, >>, ^, &, &=, |=: (i) bitwise shift on left and right, logical or and and
&&, ||, &&=, ||=: (i) logical "and" and "or" operator
≅ / =~, ~~: (i) regex operator and smartmatch operator
∉, ∈, ∊, ∍, ∋, ∌, ⊂, ⊄, ⊆, ⊈, ⊃, ⊅, ⊇, ⊉, ≡, ≢, ⊖, ∩, ⊍, ∪, ⊖, ⊎, ∖: (i) set operators
<=> : (i) X <=> Y says yield -1 if X < Y, 0 if X == Y, or -1 if X > Y
∘: (i) function composition infix operator
?:: (?) tenary operator

List of all operators from highest precedence to lowest

left terms and list operators (leftward)
right grouping operator ( )
left method call operator .
nonassoc ++, --, √ and unary prefix … / ...
right **, ⁰, ¹, ², ³, ⁴, ⁵, ⁶, ⁷, ⁸, ⁹
right !, ~, \ and unary + and -
left =~, !~
left *, /, %
left +, -, ., ∘
left ∩, ⊍
left ∪, ⊖, ⊎, ∖
chained ∈, ∊, ∉, ∋, ∍, ∌, ≡, ≢, ⊂, ⊄, ⊃, ⊅, ⊆, ⊈, ⊇, ⊉, ≼, ≽
left <<, >>
nonassoc named unary operators
nonassoc isa
chained <, >, <= / ≤, >= / ≥
chain/na ==, !=, <=>, ~~
left &
left |, ^
left &&
left ||, //
nonassoc .., lonely operator … / ...
right ?:
right =, :=, &=, |=, &&=, ||=, +=, /= / ÷=, -=, //=, *=, .=, %=, last, break, redo, and dump
list ,, =>

Comments

Single line comments are done with # and multi-line comments with ---

# single line comment
---
multi
line
comment
---

Delimiter

Pair delimiters

The following pair delimiters can be used as delimiters for quoted values and regular expression operators.

( )       [ ]       { }       < >
⦗ ⦘       ⧼ ⧽      〈 〉      ❨ ❩
❲ ❳       ❴ ❵       ⟅ ⟆       ⟦ ⟧
« »       » «       ‹ ›       › ‹
〈 〉    〈 〉     《 》     「 」
„ ”       “ ”       ‘ ’       ‚ ’
『 』     【 】     〔 〕    〖 〗
〘 〙     〚 〛     ⌈ ⌉       ⌊ ⌋
❪ ❫       ❬ ❭       ❮ ❯       ❰ ❱
⟨ ⟩       ⟪ ⟫       ⟬ ⟭       ⟮ ⟯
⦃ ⦄       ⦅ ⦆       ⦋ ⦌       ⦍ ⦎
⦏ ⦐       ⦑ ⦒

Examples

let x = [ qw(one two three) ]

# [ "Three", "Two", "One" ]
let b = x.map(:.cap).rev

# [ "0ne", "tw0", "three" ]
x =~ s<o>«0»

Single character delimiter

We also have a restricted set of delimiters for quoted values and regular expression operators.

/ | % "  '

Examples

let a = [ qw|ONE TWO THREE| ]
a.each: .lc.say

say q"interpolation won't work"

say qq<interpolation works, array: #a>

# [ "0ne", "Tw0" ]
a.grep({|x| x =~ m|o|i }).map(:s|o|0|r).map(:.ucfirst).say

Variables

Maat has four types of variables: package, lexical, temporary and static variables.

A module file has a .mm extension, a package is a namespace, variables who are fully qualified are known as package variables, there is no one-to-one mapping between a namespace and module file, therefore multiple namespaces can be define in a single module file but this is not a good practice.

Package variables can be accessed from other packages using their fully qualified name and lexically scoped variables cannot be accessed from outside the package in which they were declared.

A temporary variable is a variable that is lexically scoped and refers to a package variable declared from another package if the name of the temporary variable at declaration is fully qualified, otherwise it refers to a package variable of the same name declared in its own package. Any modification made to temporary variables remains local to their scopes of declaration, thus, out of these scopes, package variables they refer to remain untouched. You cannot temporarize lexically scoped variables and all package variables regardless of their types can to temporarized.

We declare package variables with the keyword our, lexically scoped variables with let and temporary variables with temp.

package One::Two {
    our x = [ qw<one two three> ]

    let a = {one => 1}
    {
        # a: {one => 1, two => 2}
        let a += {two => 2}

        # could still use "One::Two::x" at declaration
        temp x = {}
        # empty hash
        say One::Two::x
    }

    # output: {one => 1}
    a.say
    # output: [ qw<one two three> ]
    x.say
}

package One::Two::Three {
    # refers to the package variable "x" declared in the namespace "One::Two"
    say One::Two::x

    # compiler fails and tells that "a" isn't declared in namespace "One::Two::Three"
    say One::Two::Three::a
}

Static variables are lexically scoped variables that when defined in a function or block, retains their values between recalls and jumps. We declare static variables with the state keyword.

fun incr(n) {
   state k = n

   return k if ++k == 9
   __FUN__(nil)
}

# output: 9
say incr(5)

A constant variable when declared is lexically scoped by default unless you explicitly indicate that it is a package variables.

# lexically scoped declaration of a constant
const z = 4

# constant package variables
const our (x, y) = (2, 10)

Special variables

Some special variables are package variables(p) while others are lexically scoped(l). Also, some these variables are writable(w) while others are read-only(r).

Type I special variables

We expand the content of a type I special variable using the sigil $. It is prohibited to declare a variable with a sigil, regardless of whether or not it corresponds to any of the following.

say "Running #{$0} on #$OS"

v: (r,p) Maat version
o: (r,p) OS on which Maat was build
,: (w,p) cutput field separator
/: (w,p) input record separator, new line by default
\: (w,p) output record separator(it is what trails print), it is an empty string by default
|: (w,p) if true, do not wait when buffer is full, flush to the associated stream for every read/write operation
": (w,p) separator char for arrays when interpolated in double-quoted strings and regexs
$: (r,p) pid of the current running process
0: (r,p) name of the executing program
(, ): (r,w,p) real and effective gid of the current process, only works on OS supporting membership
<, >: (r,w,p) real and effective uid of the current process
f: (w,p) an array object containing the result of .split when using maat's -a, -n, and -F CLI options
*: (r,l) id of the current maatine, unique to each maatine
.: (r,l) line number for the last accessed file handle,
!: (r) retrieve errors from syscalls

Type II special variables

Any of the following variables in the exception of _ declared in your Maat code will abort the compilation process.

_: (w,l) topic variable, lexically scoped

A topic variable _ is declared as a lexically scoped variable and assigned a value when topicalizing with with, given, for or anonymous functions having undeclared parameters. In contrary to Perl, _ is lexically scoped which is important as Maat natively support concurrency.

for ^5 {
    let _
}

However, there are exceptions, for example the above declaration of _ will fail during compilation since it is already declared and used by the for-loop.

ENV: (w,p) a Map object which contains your current environment variables
PATH: (w,p) an Array object which contains the absolute path to directories where maat searches for modules
INC: (w,p) a Map, which map each imported module to their path location on disk
SIG: (w,p) for traping signals, map a signal name to a Fun object to be called when a triggered signal is trapped
ARGV: (w,p) an Array object containing command line arguments
ARGC: (w,p) a Num object representing the number of command line arguments
DATA: (w,p) represents a file handle to manipulate data under the __DATA__ special token in your maat code
__FILE__: (r,p) a Str object, it is the name of the source file in which it occurs.
__FUN__: (r,l) it returns the current function object if enclosed by it, otherwise, nil.

As any other non-constant package variable, all these writable package variables can be temporarized.

Special token

__DATA__

__DATA__ is not a variable. Hmm... it is a special token you fit into your maat code right at the end so that whatever data following it can be obtained via a file handle in the special variable DATA.

{
    temp $/ = ''
    say DATA.readline # outputs what follows __DATA__
}
__DATA__
This is not code but rather
data accessible via "DATA"
This is a nice feature is from Perl

Constants

π: Pi
ℇ: Euler constant
ℎ: Planck constant
ℏ: Planck constant over 2 pi

Assignments

You can use the accumulator and destructor operator in assignments, here are some examples which are self-documentary.

let (a, b, c, d, e, f)
let array = [1, 2, 3, 4, 5]

(a, b, c)    = 2, 10, -1, 5 # a: 2, b: 10, c: -1
(a, b, c)    = array        # a: [1, 2, 3, 4, 5], b: nil, c: nil
(a, b, c)    = [2, 4, 5]... # a: 2, b: 4, c: 5
(a, b, ...c) = array..., 10 # a: 1, b: 2, c: [3, 4, 5, 10]
(a,,b)       = array...     # a: 1, b: 3

# fails during compilation, only use '...' at the end
(a, ...b, c) = 2, 4, 5

(e, f) = (10, -1) # e: 10, f: -1
(e, f) = (f, e)   # e: -1, f: 10

Types

Maat has ... builtin objects, types are objects and objects are types, check details on each types here.

Blocks and Flow Controls

We separate statements with a generic newline or a semicolon in case we have more than one statement on a single line.

Blocks

[ LABEL: ] { CODE }

say 1
say 2; say 3
{ say 1 }; { say 4 }

{
    say "one"
    { say "two" }

    # recall the current block
    _BLOCK_
}

block: {
    state x = 2
    say x++
    redo block if x < 20
}

The do statement
```
do { CODE }
do 'PATH/TO/A/MAAT/FILE'
```

do runs the code from the passed block or file and returns the result of the last evaluated expression.

let v = do { 2 }

# output: 2
say v

# output: 3
(do { 3 }).say

do { false } || die "failed"

# x: 18
let x = do { 2 ** 4 } + 2

Topic variables

Maat does topicalization with flow control statements and anonymous functions a way similar to that in Perl and Raku. It is important to understand this now to avoid confusion when reading the below specification. Here, we'll focus on topicalization regarding flow controls and the one about functions will be exlpained later.

Topicalization? What is it? first appeared in Perl, topicalization is a technique used to apply a set of operations on one or a group of specific targets, it involves making the topic of operations more accessible in code. If not explicitly defined, a topic variable is represented by the type II special variable _ which holds the current default or implied argument for certain operations. Topica- lization allows you to use this special variable implicitly or explicitly within your code to refer to the current topic without having to explicitly declare it as parameter to each operation. An example is using the default topic variable in an anynomous function which implicitly means the anonymous function take a single parameter and the default topic variable refers to it. Another example is using the default topic variable within the block of the with construct to implicitly refer to the return value of its conditional expression.

The if flow control statement

if EXPR [ -> TOPIC_VAR ]      { CODE }
[ elsif EXPR [ -> TOPIC_VAR ] { CODE } ]*
[ else                        { CODE } ]

EXPR if EXPR

Conditional construct if, note that paranthesis are optional.

You must explicitly defined a topic variable if the return value of the conditional expression of if or any elsif is of interest to you as this flow construct neither changes nor defines the default topic variable _.

if true { say "it is true" }

if 0 {
    say "you are a failure"
}
elsif false {
    say "still a failure, go away!!"
}
else {
    say "welcome my man!"
}


let x = Num.rand(120)
if x % 2 -> r {
    say "remainder is #{r}"
}

if has a statement modifer form where EXPR does not get executed in a new scope.

say "one" if true

let k = 2 if 1
# output: 2
k.say

The with flow control

with EXPR [ -> TOPIC_VAR ]     { CODE }
[ orwith EXPR [ -> TOPIC_VAR ] { CODE } ]*
[ else                         { CODE } ]

EXPR with EXPR

Conditional with construct, parathensis are optional as always.

with tests for definedness (that's !nil) whereas if tests for truth. Unlike the if construct, the with and orwith sets the default topic variable _ to the value returned by the their conditional expressions.

let (u, y) = 5, nil

with u { say "defined, see: #{_}" }

# output: 5
with   y          { say "never here" }
orwith u / 2 -> m { say m, u }
else              { say "and never here too" }

The with statement avoid you from doing the following

let x = (y + 1) / 2
with x { .say }

But simple do

with (y + 1) / 2  { .say }

Its statement modifer form.

# output: 2 4 4 8
for 4, 8 {
    let k = _ with _ / 2
    say k / _
}

The for loop control

for <LIST | ARRAY | MAP | RANGE | LAZY | GFun> [ -> TOPIC_VAR [ , TOPIC_VAR ]* ] { CODE }

EXPR for <LIST | ARRAY | RANGE | MAP | LAZY | GFun>

for either iterate over an iterable object or a comma separated list of values which internal is represented as an object. Iterable objects here are object of the following types: Array, Map Range, Lazy and GFun.

Here are examples of iterations over a comma seperated list of values

# three iterations
for "a", r/regex/, [2, 4] { .say }

let ar = [ qw<one two three four five> ]

# trailing comma to indicate it is a list and thus only one iteration
for ar, { .say }
# or
.say for (ar,)
# and not this otherwise you get something weird if what follows "," can be
# evaluated by the for loop or compiler bails out if it does not make sense
.say for ar,

---
We have a.len + 1 iterations, the array destruction operator is used to
break 'ar' into a list. At topic let declaration, set a custom default
value to handle situations where we are out of elements
---
for ar…, 2 -> m, n = 'default' { (n + '-' + m).say }

Iterating over an Array objects

# output: 3 3 5 4 4
for ar -> i { say i.len }

# 'ar' is now a[3 3 5 4 4] as 'j' binds the corresponding indexed element
for ar -> j {
    j = j.len
}

# output: (3, 3) (5, 4) (4, none)
for ar -> i, j = "none" {
    print "(#i, #j) "
}

.say for ar

For lazy evaluation, we iterate over a lazy object. A lazy object implements a subset of Array methods that process array elements to produce other elements. Each method call on a lazy object registers that method with its arguments so that it gets called for every lazy iteration.

let a = [qw(nairobi niamey yaounde)]

# "grep" and "map" got registered and they later on get called for every element in "a"
for a.lazy
     .grep(:/^n/)
     .map(:[.ucfirst, .len])
                            -> x { x.dump }

The when flow control

when COND [ | EXPR ]* { CODE }

EXPR when COND

the when flow control is similar the if construct but differs from how the condition is tested if COND is just an expression, then CODE gets executed if the value of the topic variable smartmatch the result of EXPR

The given topicalizer

given EXPR { CODE }

EXPR given EXPR

# output: Num, 42
given 34 {
when Num { say "Num"; proceed }
when 42  { say "42" }
default  { say "Default" }
}

For topicalization, you can also use given as a standalone statement

let x = [2, 5]
given x {
    say "variable x has two elements" if .len == 2
}

print .map {|rx| rx ** 2 } given x

looping with the loop construct

loop [ [ INIT ] ; [ COND ] ; [ STEP ] ] { CODE }

Just like the C-for loop

loop let k = 0; k ≤ 20; k² { k.say }

# you can skip some parts
loop let k = 0;;k++ {
    k.say
    break if k == 10
}

loop { say "looping forever" }

while and until

The basic while and until loop.

let k = 6

while k > 1 {
    k.say
    k--
}

until k == 0 {
    say "not entering here"
}

do-while/until

do { CODE } while COND

do { CODE } until COND

let k = Set.new(2, 4, 5)
let b = [2, 7, 3]

do {
k.push(b.pop)
} while [2, 7] ∉ k

do {
say "forever"
} until false;

loop control statments next, break, and redo

break [ LABEL ]
next  [ LABEL ]
redo  [ LABEL ]

use loop control statements to control the behavoir of loop and non-flow control blocks

next: just like C's continue loop control statement
break: just like C's break loop control statement
redo: to rerun current loop block without evaluating the conditional

if the LABEL is omitted, the control statement refers to the innermost enclosing loop or non-flow control block.

labels

labels permits you to label blocks and flow controls so as to be able to perform jumps using control statements like redo, break and next.

# an infinite loop with prints "one"
ONE: {
    say "one"
    redo ONE
}

# print "two" to the stdout and repeatly print "three"
TWO: {
    say "two"
    THREE: {
        say "three"
        redo THREE
    }
    # dead code
    say "never gonna be executed"
}

fun do_sleep(n) {
    LOOP: for ^10 {
        break LOOP when n
        .sleep
    }
}

Execute once in a loop/function with once
```
once STATEMENT
```

once gives you the possibility to execute a statement within a loop only once regardless of the number of iterations. One great advantage it offers is freeing us from using a conditional construct to avoid the execution of a statement.

let amap = {qw(one 1 two 2 three 3)}

amap.each_kv {|k,v|
    once say 'only once!'
    printf "%s => %d\n", k, v
}

Handling exceptions with try-catch-finally

try { CODE } catch ( EXCEPTION_VAR ) { CODE } [ catch () { CODE } ]* [ finally { CODE } ]

try-catch for handling exceptions.

Concurrency with the ma statement prefix
```
ma METHOD_CALL
ma FOR_LOOP
```

ma is a statement prefix for function calls and the for loop, it is responsible of running code concurrently using maatines. When prefixed to function calls, it runs the function in a new lightweight thread known as a Maatine.

fun just_sleep(n) { n.sleep }

for 10..20 -> time {
    ma just_sleep(time)
}

When ma is used along side with a for loop, each block runs run on its own Maatine. In Maat, you'll never have to care about concurrent access to shared memory because synchronization is done by Maat itself.

ma for ^10 { .sleep }

Functions

[ mul ] fun NAME [ ( [  [ PARAM [ = DEFAULT_VALUE ] ] [, PARAM [ = DEFAULT_VALUE ] ]* ] ) ] { CODE }

{ [ | PARAM [ = DEFAULT_VALUE ] [, PARAM [ = DEFAULT_VALUE ] ]* | ] CODE }

: EXPR

Functions are first class values and hence they can be assigned to variables. The use of parantheses during a function call is optional while its usage in a function definition is mandatory if and only if that function takes arguments.

fun hello_world {
    say "Hello, World!"
}

hello_world()

Here we are declaring an anonymous function which takes a single parameter and we then call it.

let sleep = {|x| x.sleep; say "slept for #x seconds" }
sleep.call(5)

You can use the other syntax if your anonymous function is just a single expression. __FUNC__ does not work here!

let sleep = :5.sleep
sleep.call

The default Topic Variable `_`

The type II special variable _ is called a topic variable, this variable can be implicitly refered on anonymous functions and some flow control blocks. The usage of this default topic variable within the code of an anonymous function implies that this anonymous function takes a single argument whose parameter wasn't explicitly declared with | ... | and hence defaults to _.

It is possible to omit _ when calling a method on the content of a topic variable.

let anony = { say _.Str * 2 }

# output: tanzaniatanzania
anony.call("tanzania")

# Err: takes only one arg as the topic let is used in anony
anony.call("a", "b")

# .ucfirst is the same as _.ucfirst
let ar = {qw<tcheukam madjou monthe>}
say ar.map(:.ucfirst)

The usage of the default topic variable in an anonymous function having declared parameter or expecting no parameters refers to the one from outer scopes.

The method .times of the Num type expects no argument when called and thus the default topic variable refers to the one from the outer scope.

# output: 88888888 666666 666666
ar.map(:.len).each { .times { .print } }

Maat has support for multiple dispatching and named arguments. Mixing named arguments with unnamed ones brings a lot of confusion in your code and hence either you name all your arguments or you don't name anything at all.

fun call(c, n) { c.call(_) for ^n }
call({ .say }, 5)

mul fun who(name, age) {
    say "Hello, my name is #name, I'm #{age}yo"
}

mul fun who(name) {
    say "Hello, my name is #name!"
}

who("kueppo", 20)
who("madjou")
who(age => 5, name => liza)

# no candidates for this and thus fails at compile time
who(age => 10)

fun mul(s, k) { s * k }
fun mul(s)    { s * 2 }

mul("one").say    # output: oneone
mul("two", 5).say # output: twotwotwotwo

Maat has what we call an accumulator operator, this accumulator operator in a method/function definition is a prefix operator used to collect the rest of extra indefinite number of arguments as an array into the last declared parameter of that function/method during calls. This is done by prepending … to the last declared parameter at function/method definition.

# using the array accumulator operator for variadic arguments
fun count(name, …counts) {
    printf "You have %d %ss\n", counts.len > 0 ? counts.sum : 0, name
}

count("pineaple", 2, 4, 10) # output: You have 16 pineaples
count("orange")             # output: You have 0 oranges

fun sum(...ar) { ar.sum }

# they don't make sense at all! fail at compilation
fun bad_func1(a, ...b, c)    { ... }
fun bad_func2(...a, b, c)    { ... }
fun bad_func3(...a, b, ...c) { ... }
fun bad_func4(a, ...b, ...c) { ... }

The reason why fun optionally precedes { ... } when defining anonymous functions is mainly for syntatic sugar and so to avoid confusion with blocks, it is prohibited to declare an anonymous function as a value the following way

# fails at compile time
{ .say }.call(20)

But this works

Fun.new({ .say }).call(20)
(:.say).call(20)
fun { .say }.call(20)

Traits

Functions as well as methods support the :save trait, the :save trait caches the return value of a function call to avoid recomputation of the same function call when doing recursive calls. This trait can help you do dynamic programming with less overhead.

fun fib(n) :save {
    n < 2 ? n : __FUN__(n - 1) + __FUN__(n - 2)
}

Generator function

A Generator function for gathering values with take, a generator function is an iterable object where each iteration resumes from where the generator function was paused by a take call.

fun factors(n) {
    let k = 1

    while k ** 2 < n {
        take k, n.div(k) if n % k 
        k++
    }
    take k if k ** 2 == n
}

.say for factors(36)

Classes

class CLASS_NAME {
    <
        <
            <
                < has | state > ATTR_NAME :TRAIT [ = DEFAULT_VALUE ]
            >
            |
            <
                [ state ] meth METHOD_NAME
                [
                    ( [ PARAM [ = DEFAULT_VALUE ] [, PARAM [ = DEFAULT_VALUE ] ]* ] )
                ]
                { CODE }
            >
        >+
    |
        ...
    >
}

# unimplemented classes
class B { ... }
class C { ... }

# "is" for inheritance and "does" for roles
class A :is(B, C) :does(D, E) {
    # read-only attribute, ro: say A.x; not possible: A.x = "some value"
    has x :ro   

    # read-write attribute with default value '0', write: A.y = 2; read: say A.y
    has y :rw = 0

    has z

    # static variable which is accessible to all objects via class 'A': A.count
    state count = 0

    # static method (A.m()), self isn't valid here as with static variables
    state meth m() {
        ...
    }

    meth xyz() {
        # self.x, self.y, etc.
        ...
    }

    mul meth amethod() { ... }

    # takes a parameter x
    mul meth amethod(x) { ... }

    # defining a method 'priv' as private, oi means only-in
    meth priv() :oi { ... }
}

List of traits supported by attributes and methods

rw: Make attribute read-write
ro: Make attribute read-only
built: Make attribute private but can be set when instanciating
oi: Make method private to the class

To every object is associated a metaobject which permits object introspection, given a variable obj containing an abitrary object, this object can be introspected via its metaobject by using the .^ method call operator.

obj.^who      # returns the class from which obj was instanciated
obj.^name     # name of the class from which the object was instantiated
obj.^methods  #

Roles

role ROLE_NAME {
    <
        <
            [ state ] meth METHOD_NAME
            [
                ( [ PARAM [ = DEFAULT_VALUE ] [, PARAM [ = DEFAULT_VALUE ] ]* ] )
            ]
            { CODE }
        >+
    |
        ...
    >
}

A class does

role D { ... } # unimplemented role

role E {
    meth eat(x) {
        say "#{self.name} eats #x"
    }
}

Regular Expressions

Maat uses Perl compatible regular expressions(PCRE2).

See section on the Regex type for more information.

Async Programming with Works

Maat has two concurrent programming model which are the asynchronous and thread-like model. The thread-like model is what we call Maatines and the async model is what we call Works. Async functionality is implemented with the help of Maatines, so yeah… it is just an abstract layer over it. A Work encapsulate a computation called a Work which runs internally as a new or updated Maatine object.

A Work has three possible state which are the Do, Done and Failed state.

In the Do state, Work is either not started or on progress.
In the Done state, Work is Done and has its result saved for latter retrieval.
In the Failed state, an exception was thrown when the Work was doing its work and hence Failed.

The below code creates a new Work which is initially in the Do state, completes its work with the done method and from there checks its updated status and result with the status and done methods respectively.

let w = Work.new   # new Work object
say w.status       # output: Do
w.done("I'm done")
say w.status       # output: Done
say w.result       # output: I'm done

You can return a Work that is already done with the static done method and you can also return a work that has already failed with the failed method.

Work.done.status.say   # output: Done
Work.failed.status.say # output: Failed

We can chain Works just like you do with Promises in Javascript

The chaining mechanism of Works in Maat is completely different from that of Promises in javascript.

Listen to the story: you first start by creating a work with Work.does which returns a work object on which you can but not only do either of the following:

Call the .catch method to handle any exception on the created Work, it returns back the same object.
Call the .then method to create and return a new Work to be scheduled for execution if Work object invoker is Done.

If the exception of the work created by .then is not handled, it inherits its exception handler from the highiest top level Work.

let w = Work.does({ sleep 4; 10 })
            .catch({|e| say "Catched: #{e}" })
            .then({ say "My handler is the one above"; _ + 2 })
            .then({|r| say "Mine is below"; r - 2 })
            .catch({|e| warn "Couldn't sub 2 from 12? ans: #{e}" })

say abide w # output: 10

To abide a work say w with function abide is to call the method .result on it. abide function can take multiple Works as argument and return their results in an Array. If a work with a handled exception encounters an exception, calling .result on it returns nil.

You can setup a work to do work by sleeping for a given amount of time using the static .for method, yes! sleeping is a kind of a work, even in real life :).

Work.for(5)
    .then({ say "Previous work was to sleep 5 seconds" })

The above is kinda similar to this one and both of them can be used to build timers.

Work.does(:5.sleep)
    .then(:…)

You can also set a work to do work by waiting til a specified time using the .til static method

Work.til(Date.now + 10)
    .then(:say "Previous work is done at ", _ )

You can use the Work.allof method to return a new Work object that will be Done when all the work passed as arguments are either Done or Failed. The value return by .result method call on the returned work object is always true and practically useless.

let k = ^5.map {|i| Work.does(:sleep i) }

Work.allof(k)
    .then: k.map(:.result).sum.say

See section on the Work type for more information.

Maatines

Maatines are lightweight threads managed by the Maat runtime, they are extremely easy and less costly to create and destroy. Internally, Maat has a high performant scheduler which schedules the executions of Maatines across OS threads.

See section on the Ma type for more information.

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email: tcheukueppo@yandex.com

Maat

Operators

Lonely operator

Basic unary operators

Named unary operators

Named list operators

Named binary operators

Binary operators for maat objects

List of all operators from highest precedence to lowest

Comments

Delimiter

Pair delimiters

Examples

Single character delimiter

Examples

Variables

Special variables

Type I special variables

Type II special variables

Special token

Constants

Assignments

Types

Blocks and Flow Controls

Topic variables

Functions

The default Topic Variable `_`

Traits

Generator function

Classes

Roles

Regular Expressions

Async Programming with Works

Maatines

Packages

Phasers

maat.md 35 KB 履歴 Raw

email: tcheukueppo@yandex.com

Maat

Operators

Lonely operator

Basic unary operators

Named unary operators

Named list operators

Named binary operators

Binary operators for maat objects

List of all operators from highest precedence to lowest

Comments

Delimiter

Pair delimiters

Examples

Single character delimiter

Examples

Variables

Special variables

Type I special variables

Type II special variables

Special token

Constants

Assignments

Types

Blocks and Flow Controls

Topic variables

Functions

The default Topic Variable _

Traits

Generator function

Classes

Roles

Regular Expressions

Async Programming with Works

Maatines

Packages

Phasers

maat.md 35 KB

履歴 Raw

The default Topic Variable `_`