Метапрограмиране с Nimrod
Varna Conf, Юли 2014
Автори Захари Караджов, Борислав Станимиров
Какво сме ние?
Захари
- Президент на Даркиум - прави браузър
- Програмира професионално от 10 години
- Знае езици за програмиране
- Да, този също го знае
- Е, този вече само Бойко Банчев го знае
- Вторият по количество код в Нимрод, след автора - Андреас Румпф
- Като цяло пич
Боби
- Президент на това да си безработен
- Програмира професионално от 12 години
- Най-вече игри
- Пише open source
- Води курсове
- Иска С++ да умре най-сетне
- Като цяло, също така пич
Предговор
- Какво е метапрограмиране?
- Не това, което се изпълнява когато потребителяt ползва програмата
- Програмиране за програмирането
- Изпълнява се от компилатора
- Супер елементарен пример:
a + b * c- NextGen, Супер як, 2.0, buzzword, buzzword, buzzword език за програмиране.
- nimrod-lang.org
Ордьовър
- Текущото състояние на света
- Ако искаме бързодействие - плачем със С++
- Ако можем да си позволим лопати хардуер - сме щастливи с Руби
Сензационна теза
Представете си любимия си език, любимата си библиотека, любимия си код.
Всички преимущества, които виждате в тях, могат успешно да се постигнат Nimrod. А също така и голяма част от недостатъците им да изчезнат.
Сензационна теза две
Nimrod има потенциала да стане най-използваният език на света вселената.
Nimrod
- Силно типизиран
- Компилиращ се
- Closures
- Итератори
- CTFE
- Type inference
- Garbage collection, но и RAII
- Resumable functions - Concurrency, Async IO
- (нещо като) ООП
А сега: Примери
HTML Template Engine
Markaby.nim
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| type Article = object | |
| title, body: string | |
| proc myPage(articles: seq[Article]): string = | |
| return html: | |
| head: | |
| title "Боза.цом" | |
| css "moar-blink.css" | |
| body: | |
| ul: | |
| for article in articles: | |
| li: | |
| h2 article.title | |
| p article.body |
Markaby.nim
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| template html(matter: stmt) {.dirty.} = | |
| var result = "" | |
| matter | |
| template tag(tagName) = | |
| template `tagName`(attrs: varargs[expr], matter: stmt = nil) {.dirty.} = | |
| # formatAttrs затваря тага и при нужда добавя inner текста | |
| result.add("<" & astToStr(tagName) & formatAttrs(attrs)) | |
| matter | |
| result.add("</" & astToStr(tagName) & ">") | |
| tag head; tag link; tag body | |
| tag ul; tag li; tag title | |
| tag p; tag h2 | |
| template css(file) {.dirty.} = | |
| link(relation = "stylesheet", href = file) | |
| macro formatAttrs(args: seq[expr]): expr = | |
| result = newCall("&") | |
| var innerTexts = newSeq[string]() | |
| for arg in args: | |
| if arg.kind == nnkExprEqExpr: | |
| result.addParams($arg[0], "=", quoteString($arg[1])) | |
| else: | |
| innerTexts.add($arg) | |
| result.addParams ">" | |
| result.addParams innerTexts |
...което се компилира до...
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| proc myPage(articles: seq[Article]): string = | |
| var result = "" | |
| result.add("<" & "head" & ">") | |
| result.add("<" & "title" & ">") | |
| result.add("Боза.цом") | |
| result.add("</" & "title" & ">") | |
| result.add("<link " & "relation" & "=" & "\"stylesheet\"" & | |
| "href" & "=" & "\"moar-blink.css\"" & ">") | |
| result.add("</" & "link" & ">") | |
| result.add("</" & "head" & ">") | |
| result.add("<" & "body" & ">") | |
| result.add("<" & "ul" & ">") | |
| for article in articles: | |
| result.add("<" & "li" & ">") | |
| result.add("<" & "h2" & ">") | |
| result.add article.title | |
| result.add("</" & "h2" & ">") | |
| result.add("<" & "p" & ">") | |
| result.add article.body | |
| result.add("</" & "p" & ">") | |
| result.add("</" & "li" & ">") | |
| result.add("</" & "ul" & ">") | |
| result.add("</" & "body" & ">") | |
Expression Pattern Matching
... ту дъ рескю
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| template optAdd1 {x = y; x.add(z)} (x, y, z: string) = | |
| x = y & z | |
| template optAdd2 {x.add(y); x.add(z)} (x, y, z: string) = | |
| x.add(y & z) |
...да погледнем кода отново...
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| proc myPage(articles: seq[Article]): string = | |
| var result = "" # Тези редове съответстват на правилото: | |
| result.add("<" & "head" & ">") # {var x = y; x.add(z);} (x, y, z: string) = | |
| # x = y & z | |
| result.add("<" & "title" & ">") | |
| result.add("Боза.цом") | |
| result.add("</" & "title" & ">") | |
| result.add("<link " & "relation" & "=" & "\"stylesheet\"" & | |
| "href" & "=" & "\"moar-blink.css\"" & ">") | |
| result.add("</" & "link" & ">") | |
| result.add("</" & "head" & ">") | |
| result.add("<" & "body" & ">") | |
| result.add("<" & "ul" & ">") | |
| for article in articles: | |
| result.add("<" & "li" & ">") | |
| result.add("<" & "h2" & ">") | |
| result.add article.title | |
| result.add("</" & "h2" & ">") | |
| result.add("<" & "p" & ">") | |
| result.add article.body | |
| result.add("</" & "p" & ">") | |
| result.add("</" & "li" & ">") | |
| result.add("</" & "ul" & ">") | |
| result.add("</" & "body" & ">") |
...след прилагане на първото правило...
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| proc myPage(articles: seq[Article]): string = | |
| var result = "" & "<" & "head" & ">") # След прилагане на правилото | |
| result.add("<" & "title" & ">") # можем да го приложим отново за | |
| # новополучения код | |
| result.add("Боза.цом") | |
| result.add("</" & "title" & ">") | |
| result.add("<link " & "relation" & "=" & "\"stylesheet\"" & | |
| "href" & "=" & "\"moar-blink.css\"" & ">") | |
| result.add("</" & "link" & ">") | |
| result.add("</" & "head" & ">") | |
| result.add("<" & "body" & ">") | |
| result.add("<" & "ul" & ">") | |
| for article in articles: | |
| result.add("<" & "li" & ">") | |
| result.add("<" & "h2" & ">") | |
| result.add article.title | |
| result.add("</" & "h2" & ">") | |
| result.add("<" & "p" & ">") | |
| result.add article.body | |
| result.add("</" & "p" & ">") | |
| result.add("</" & "li" & ">") | |
| result.add("</" & "ul" & ">") | |
| result.add("</" & "body" & ">") |
...и още веднъж...
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| proc myPage(articles: seq[Article]): string = | |
| var result = ("" & "<" & "head" & ">" & "<" & "title" & ">") | |
| result.add("Боза.цом") | |
| result.add("</" & "title" & ">") | |
| result.add("<link " & "relation" & "=" & "\"stylesheet\"" & | |
| "href" & "=" & "\"moar-blink.css\"" & ">") | |
| result.add("</" & "link" & ">") | |
| result.add("</" & "head" & ">") | |
| result.add("<" & "body" & ">") | |
| result.add("<" & "ul" & ">") | |
| for article in articles: | |
| result.add("<" & "li" & ">") | |
| result.add("<" & "h2" & ">") | |
| result.add article.title | |
| result.add("</" & "h2" & ">") | |
| result.add("<" & "p" & ">") | |
| result.add article.body | |
| result.add("</" & "p" & ">") | |
| result.add("</" & "li" & ">") | |
| result.add("</" & "ul" & ">") | |
| result.add("</" & "body" & ">") |
...и така натататататък...
...и така нататък казах!
Докато стигнем до този код на С++...
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| NimString myPage(const Sequence<Article>& articles) | |
| { | |
| NimString result = | |
| "<head><title>Боза.цом</title>" | |
| "<link relation=\"\stylesheet\" href=\"moar-blink.css\></link></head>" | |
| "<body><ul>"; | |
| for(const auto& article: articles) | |
| { | |
| result.add(Concat("<li><h2>", article.title, "</h2><p>", article.body, "</p></li>")); | |
| } | |
| result.add("</ul></body>"); | |
| return result; | |
| } |
Script Language Binding
RubyBind.nim
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| class Character | |
| attr_reader :name, :health | |
| def initialize(@name) | |
| @health = 100 | |
| end | |
| def equip(@weapon) | |
| puts "#{@name}: I will slash my enemies with my #{@weapon.name}" | |
| end | |
| def attack(name) | |
| puts "#{@name}: Eat my #{@weapon.name}, #{name}" | |
| enemy = find_character(name) | |
| enemy.take_damage(@weapon.damage) | |
| end | |
| def take_damage(damage) | |
| @health -= damage | |
| puts "#{@name}: Aaaarghhhhh" | |
| end | |
| end |
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| import ruby | |
| let characterClass = rubyGlobal("Character") | |
| var c = characterClass.new("Bozo") | |
| type Weapon = ref object | |
| name: string | |
| damage, durability: int | |
| c.equip(Weapon(name: "Holy Sword of Ultimate Imbalance", | |
| damage: 99999999, | |
| durability: 666666666)) | |
| c.attack("Kiro") |
Изход:
Bozo: I will slash my enemies with my Holy Sword of Ultimate Imbalance
Bozo: Eat my Holy Sword of Ultimate Imbalance, Kiro
Kiro: Aaaarghhhhh
Прехвърляне на неща в Ruby
- В общият случай тривиална задача
- Предизвикателството са обектите
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| proc toRuby(v: int): RubyValue = rb_int2inum(v) | |
| proc toRuby(v: string): RubyValue = rb_str_new2(v) | |
| proc toRuby(v: ref object|tuple): RubyValue = | |
| var rubyClass {.global.} = makeRubyType(v.type) | |
| GC_ref(v) | |
| return rb_data_object_alloc(rubyClass, nil, GC_unref, v) |
Експортиране на обекта
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| var NimrodModule = rb_define_module "nimrod" | |
| proc makeRubyType(RegisteredType: type): RubyValue = | |
| result = rb_define_class_under(NimrodModule, RegisteredType.name, nil) | |
| for fieldName, fieldType in RegisteredType.fieldPairs: | |
| proc getterImpl(self: RubyValue): RubyValue = | |
| let | |
| nativeSelf = cast[RegisteredType](rb_data_ptr(self))) | |
| fieldValue = readField(fieldName, nativeSelf) | |
| return fieldValue.toRuby | |
| rb_define_method(result, fielName, getterImpl) | |
Експортирането на сетъри и методи е оставено за упражнение на читателя
Боравене с Ruby обекти
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| proc `.=`*(self: RubyValue, field: static[string], value): RubyValue = | |
| const rubyMethod = field & "=" | |
| return rb_funcall(self, rubyMethod, 1, [value.toRuby]) | |
| proc `.()`*(self: RubyValue, methodName: static[string], | |
| rbArgs: varargs[RubyValue, toRuby]): RubyValue = | |
| return rb_funcall(obj, methodName, rbArgs.len, rbArgs) |
.() функцията майка
- swizzle
a.zyx = b.xxy
jsonRequest("http://search.twitter.com/search.json?q=#VarnaConf").tweets[0].author
И това компилирано
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| VALUE NimrodModule = rb_define_module("nimrod"); | |
| VALUE getterImpl_Name(VALUE self) { | |
| return static_cast<Weapon*>(rb_data_ptr(self))->name; } | |
| // И същото за getterImpl_Damage и getterImpl_Durability | |
| VALUE MakeRubyType_Weapon() { | |
| VALUE weaponClass = rb_define_class_under(NimrodModule, "Weapon", NULL); | |
| rb_define_method(weaponClass, "name", getterImpl_Name); | |
| rb_define_method(weaponClass, "damage", getterImpl_Damage); | |
| rb_define_method(weaponClass, "durability", getterImpl_Durability); | |
| return weaponClass; | |
| } | |
| void toRuby(Weapon* weapon) { | |
| static VALUE RubyWeapon = MakeRubyType_Weapon(); | |
| GC_ref(weapon); | |
| return rb_data_object_alloc(RubyWeapon, nil, GC_unref, weapon); | |
| } | |
| void main() { | |
| VALUE character = rb_gv_get("Character"); | |
| VALUE args0[] = {toRuby("Bozo")}; | |
| rb_funcall(character, "new", 1, args0); | |
| VALUE args1[] = {toRuby(new Weapon("Holy Sword of Ultimate Imbalance", 999, 666))}; | |
| rb_funcall(character, "equip", 1, args1); | |
| VALUE args2[] = {toRuby("Kiro")}; | |
| rb_funcall(character, "attack", 1, args2); | |
| } |
Command Line Arguments
ping.nim
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| var options = parseOptions: | |
| desc "ping - send ICMP ECHO_REQUEST packets to network hosts" | |
| flags: | |
| c count "Number of packets to send" default(-1) | |
| i iface "Netword interface to use" optional | |
| m ttl "Sets the TTL value for each packet" default(64) | |
| t timeout "Specify a timeout, in seconds" default(3) | |
| params host | |
| echo options.host, options.timeout |
Unit тестове
WorldCupTest.nim
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| suite "World Cup Simulator": | |
| setup: | |
| var brazil = Team.new("Brazil") | |
| var germany = Team.new("Germany") | |
| var match = Match.new(brazil, germany) | |
| test "Exact Score": | |
| match.elapseTime 30.minutes | |
| check match.score == Score(0, 5) | |
| test "Referee": | |
| match.complete | |
| check germany.defenders.yellowCards > 3 | |
| # output is Check Failed [germany.defenders.yellowCards > 3] | |
| # germany.defenders.yellowCards was 0 | |
| # germany.defenders was ["Lahm", "Boateng", "Hummels"] | |
Още гъзарии
- ORM
- Генериране на сериализация
- Функционално програмиране
- Аспектно програмиране
- "Всички функции са темплейтни", дет вика Захари
- Ефектни ефекти
- И въобще... каквото ви душа иска
Малко неприятности :(
- Има тук-таме бъгчета. Но не в компилирането...
- Няма много пълна стандартна библиотека
- Няма много яко IDE
- Някои хора (Боби) не се кефят на питонски стил на влагане
Бъдеще
"През 2017-та Нимрод ке почне да става за сериозен софтуер"
"През 2019-та 'секи ке пише на Нимрод"
Край
Nimrod / nimrod-lang.org
Захари Караджов / github.com/zah / @zaharyk
Борислав Станимиров / ibob.github.io / @natcbb
Презентацията е лицензирана с Creative Commons Признание 3.0