Question

helkell frege中的hello world：

hello.fr：

module Hello where

main args = do
    putStrLn "Hello, World!"

此代码生成hello.java：

/*
  Source code is in UTF-8 encoding. The following symbols may appear, among others:
  α β γ δ ε ζ η θ ι κ λ μ ν ξ ο π ρ ς σ τ υ φ χ ψ ω « • ¦ » ∀ ∃ ∷ … → ← ﬁ ﬂ ƒ
  If you can't read this, you're out of luck. This code was generated with the frege compiler version 3.24.80
  from hello.fr Do not edit this file! Instead, edit the source file and recompile.
*/

import frege.run8.Func;
import frege.run8.Lazy;
import frege.run8.Thunk;
import frege.run.Kind;
import frege.run.RunTM;
import frege.runtime.Meta;
import frege.runtime.Phantom.RealWorld;
import frege.Prelude;
import frege.control.Category;
import frege.control.Semigroupoid;
import frege.java.IO;
import frege.java.Lang;
import frege.java.Util;
import frege.java.util.Regex;
import frege.prelude.Maybe;
import frege.prelude.PreludeArrays;
import frege.prelude.PreludeBase;
import frege.prelude.PreludeIO;
import frege.prelude.PreludeList;
import frege.prelude.PreludeMonad;
import frege.prelude.PreludeText;

@SuppressWarnings("unused")
@Meta.FregePackage(
  source="hello.fr", time=1470398249962L, jmajor=1, jminor=8,
  imps={
    "frege.Prelude", "frege.prelude.PreludeArrays", "frege.prelude.PreludeBase", "frege.prelude.PreludeIO",
    "frege.prelude.PreludeList", "frege.prelude.PreludeMonad", "frege.prelude.PreludeText", "frege.java.util.Regex"
  },
  nmss={"Prelude", "PreludeArrays", "PreludeBase", "PreludeIO", "PreludeList", "PreludeMonad", "PreludeText", "Regexp"},
  symas={}, symcs={}, symis={}, symts={},
  symvs={@Meta.SymV(offset=20, name=@Meta.QName(pack="Hello", base="main"), stri="s(u)", sig=1, depth=1, rkind=49)},
  symls={},
  taus={
    @Meta.Tau(kind=2, suba=0, tcon={@Meta.QName(kind=0, pack="frege.prelude.PreludeBase", base="[]")}),
    @Meta.Tau(kind=2, suba=0, tcon={@Meta.QName(kind=0, pack="frege.prelude.PreludeBase", base="StringJ")}),
    @Meta.Tau(kind=2, suba=0, tcon={@Meta.QName(kind=0, pack="frege.prelude.PreludeBase", base="Char")}),
    @Meta.Tau(kind=0, suba=1, subb=2), @Meta.Tau(kind=0, suba=0, subb=3),
    @Meta.Tau(kind=2, suba=0, tcon={@Meta.QName(kind=0, pack="frege.prelude.PreludeBase", base="ST")}),
    @Meta.Tau(kind=2, suba=0, tcon={@Meta.QName(kind=0, pack="frege.prelude.PreludeBase", base="RealWorld")}),
    @Meta.Tau(kind=0, suba=5, subb=6),
    @Meta.Tau(kind=2, suba=0, tcon={@Meta.QName(kind=0, pack="frege.prelude.PreludeBase", base="()")}),
    @Meta.Tau(kind=0, suba=7, subb=8)
  },
  rhos={@Meta.Rho(rhofun=false, rhotau=4), @Meta.Rho(rhofun=false, rhotau=9), @Meta.Rho(sigma=0, rhotau=1)},
  sigmas={@Meta.Sigma(rho=0), @Meta.Sigma(rho=2)}, exprs={@Meta.Expr()}
)
final public class Hello  {





final public static Func.U<RealWorld, Short> $main(final Lazy<PreludeBase.TList<String/*<Character>*/>> arg$1) {
  return Prelude.putStrLn("Hello, World!");
}

  public static void main(final java.lang.String[] argv) {
    try {
      frege.run.RunTM.argv = argv;

        PreludeBase.TST.<Short>performUnsafe($main
               (Thunk.lazy(PreludeArrays.IListSource_JArray.<String/*<Character>*/>toList(argv)))
          ).call();
      frege.runtime.Runtime.stdout.get().close();
      frege.runtime.Runtime.stderr.get().close();

    } finally { frege.run.Concurrent.shutDownIfExists(); }
  }
}

然后我编译生成的java代码，没有错误：

javac -cp frege3.jar build/Hello.class

然后我尝试运行代码：

cd build
java Hello

但这会返回错误：

Error: A JNI error has occurred, please check your installation and try again
Exception in thread "main" java.lang.NoClassDefFoundError: frege/run8/Lazy
    at java.lang.Class.getDeclaredMethods0(Native Method)
    at java.lang.Class.privateGetDeclaredMethods(Class.java:2701)
    at java.lang.Class.privateGetMethodRecursive(Class.java:3048)
    at java.lang.Class.getMethod0(Class.java:3018)
    at java.lang.Class.getMethod(Class.java:1784)
    at sun.launcher.LauncherHelper.validateMainClass(LauncherHelper.java:544)
    at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:526)
Caused by: java.lang.ClassNotFoundException: frege.run8.Lazy
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 7 more

如何在jvm上运行生成的frege java代码？

我正在使用java8

Answer 1

启动命令时，您还需要在类路径中添加frege3.jar，请尝试以下操作：

java -cp .:frege3.jar Hello

假设frege3.jar和Hello.class都在当前目录中

Answer 2

您不需要额外的javac编译，这是由frege编译器自动完成的（除非被标志抑制）。
是的，这里有一个入门文档：https://github.com/Frege/frege/wiki/Getting-Started

如何在jvm上运行生成的frege java代码？

2 个答案: