Initial project import

tools/v/vlib/build/README.md

@@ -0,0 +1,55 @@
+## Description
+
+`build` provides a small build system leveraging V(SH) for the buildscript.
+
+## Example
+
+> See also: [build_system example](https://github.com/vlang/v/tree/master/examples/build_system)
+
+```v
+#!/usr/bin/env v
+
+import build
+// .vsh automatically imports `os`, so you don't need this typically
+import os { system }
+
+const app_name = 'vlang'
+const program_args = 'World'
+
+mut context := build.context(
+	// Set the default task to `release` when no arguments are provided
+	default: 'release'
+)
+
+context.task(name: 'doc', run: |self| system('v doc .'))
+context.task(name: 'run', run: |self| system('v run . ${program_args}'))
+context.task(name: 'build', run: |self| system('v .'))
+context.task(name: 'build.prod', run: |self| system('v -prod .'))
+
+context.task(
+	name:    'release'
+	depends: ['doc']
+	run:     fn (self build.Task) ! {
+		system('v -prod -o build/${app_name} .')
+		// You could use Git to publish a release here too
+	}
+)
+
+context.run()
+```
+
+For portable `.vsh` scripts, prefer `#!/usr/bin/env v`.
+That works on BusyBox and OpenBSD too, where `/usr/bin/env -S` is not available.
+
+## Pre-Compiling
+
+Running VSH scripts requires V to compile the script before executing it, which can cause a delay
+between when you run `./build.vsh` and when the script actually starts executing.
+
+If you want to fix this, you can "pre-compile" the buildscript by building the script with
+`v build build.vsh` (or `v -skip-running build.vsh`).
+
+> You will need to rebuild every time you change the buildscript, and you should also add `/build`
+> to your `.gitignore`
+
+> If you want maximum speed, you can also `v -prod build build.vsh`