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164 строки
3.4 KiB
Plaintext
164 строки
3.4 KiB
Plaintext
Tutorial
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http://scalameta.org/tutorial/
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https://github.com/scalameta/tutorial
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download the amonite-shell (0.5.7)
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load.ivy("org.scalameta" && "scalameta" % "0.20.0")
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import scala.meta._
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$ "foo + bar".parse[Term]
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res2: Parsed[Term] = foo + bar
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$ res2.get
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res3: Term = foo + bar
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$ res3.structure // dbg-stuff
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res4: String = """
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Term.ApplyInfix(Term.Name("foo"), Term.Name("+"), Nil, Seq(Term.Name("bar")))
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"""
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$ "foo.+(bar)"
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res5: Term = foo.+(bar)
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$ res5.structure
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res6: String = """
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Term.Apply(Term.Select(Term.Name("foo"), Term.Name("+")), Seq(Term.Name("bar")))
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"""
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$ """
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def foo = bar
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/* hello world */
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foo
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"""
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res7: String = """
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....
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$ res7.parse[Term]
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res8: Parsed[Term] = <input>:2: error: illegal start of simple expression
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def foo = bar
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^
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$("{" + res7 + "}").parse[Term]
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res9: Parsed[Term] {
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def foo = bar
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/* hello world */
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foo
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}
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$ res9.structure
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Main.scala:158: value structure is not a member of scala.meta.parsers.Parsed[
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res9.structure
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^
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Compilation Failed
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$ res9.get.structure
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res10: String = """
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Term.Block(Seq[Defn.Def(Nil, Term.Name("foo"), Nil, Nil, None, Term.Name("bar
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// !!! don't see any comments
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$ res9.get.tokens
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res11: Tokens = Tokens(
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,
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{,
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,
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,
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,
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....
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def,
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...
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@ res9.get.tokens.structure
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res12: String = """
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Tokens(BOF [0..0), { [0..1), \n [1..2), [2..3), [3..4),
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...
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... [26..27), /* hello world */
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foo [f5..48), \n [48..49), } [49..50), EOF [50..50))
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"""
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// !!! preserve all the stuff
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+++++++
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+ SBT +
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+++++++
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$ val buildsbt = new java.io.File("/.../build.sbt")
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buildsbt: java.io.File = /.../build.sbt
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$ buildsbt.parse[Source]
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res14: Parsed[Source] = build.sbt:6: error: expected class or object defined...
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def ifAt...
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^
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$ scala.meta.dialects.Sbt0137(buildsbt).parse[Source]
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res18: Parsed[Source] = import sbtrelease._
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...
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def ifAtLeast(scala....)
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case class ScalaBinaryVersion...
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...
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$ res18.get.structure
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res19: String = """
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Source(Seq[Import(Seq(Importer(Term.Name...
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"""
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++++++
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+ QQ +
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++++++
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$ val foo = q"foo"
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foo: Term.Name = fool
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$ q"$foo + bar"
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res21: Term.ApplyInfix = foo + bar
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$ val q "$x + $y" = q"$foo + bar"
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x: Term = foo
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y: Term.Arg = bar
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// y type is an Argument, not a Term
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Old macros:
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class Table[T](val query: Query[T]) {
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def map[U](fn: T => U): Table[U] = macro Macros.map
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}
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object Macros {
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def map(c: Context)(fn: c.Tree): c.Tree = {
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val subquery: c.Tree = translate(fn)
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q"new Table(Map(${c.prefix}, $subquery))"
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}
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}
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val users: Table[User] = ....
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users.map(u => u.name)
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- expands into -
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val users: Table[User] = ...
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new Table(Map(users, Ref("name", classOf[String])))
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New macros sketch
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class Table[T](val query: Query[T]) {
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inline def map[U](fn: T => U): Table[U] = meta {
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val subquery: c.Tree = translate(fn)
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q"new Table(Map($this, $subquery))"
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}
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}
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val users: Table[User] = ....
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users.map(u => u.name)
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- expands into (via inline) -
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val users: Table[User] = ...
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meta{ ...; q"new Table(Map(users, $subquery))" }
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- and later into -
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new Table(Map(users, Ref("name", classOf[String])))
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+++++++++++++
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+ LIVE DEMO +
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+++++++++++++
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import scala.meta._
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object main{
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inline def apply()(defn: Any) = meta {
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val q"..$mods object $name extends { ..$early } with .. $base { $self => .. $stats}"
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val main = q"def main(args: Array[String]): Unit = { ..$stats}"
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q"..$mods object $name extends { ..$early } with ..$base { $self => $main }"
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}
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}
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// using by
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@main object Test {
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println("hello world")
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}
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