compile against a special frege version, download and install if not yet there

build.gradle

/**
  Making the Frege language available. Compiler and Runtime is all in one jar.
  To be completed.
	@author Dierk Koenig
*/
apply plugin:'java'

def frege_version = '3.21.190'
def qualifier     = 'g714a7cc'
def frege_jar     = file(System.properties.'user.home'+"/.frege/home/frege-${frege_version}.jar")

def frege_src_dir = 'src/main/frege'
def frege_build_dir = 'build/frege'


task installFrege(type: Download) {
    sourceUrl = "https://github.com/Frege/frege/releases/download/$frege_version/frege$frege_version-${qualifier}.jar"
    target    = frege_jar
}

task compileFrege(depends:installFrege, type:JavaExec) {
	jvmArgs = ["-Xss1m"]
	args = ["-d", frege_build_dir, "-sp", frege_src_dir]
	new File(frege_src_dir).eachFileRecurse {
		if (it.file && it.path.endsWith('.fr')) args += it.path
	}
	println args
	classpath = files(frege_jar)
	main = "frege.compiler.Main"
}

class Download extends DefaultTask {
    @Input
    String sourceUrl

    @OutputFile
    File target

    @TaskAction
    void download() {
       ant.get(src: sourceUrl, dest: target)
    }
}