Packages

The zipper of chapter 4 has nothing to do with todos: other programs could use it too. In this chapter it becomes a package of its own, and hello requires it.

A package of its own

Next to hello, make a directory zipper and move the zipper there:

mkdir -p ../zipper/src/zipper
mv src/hello/zipper.hf ../zipper/src/zipper/list.hf

Its first line becomes its new name, module zipper.list. Then give the package a package.hf:

import manifest

package : Package
package = { module = "github.com/you/zipper", heff = "0.4.0" }

module is where the package lives, and its last part, zipper, is the first part of its modules’ names.

Requiring it

In hello’s package.hf:

import manifest

package : Package
package =
  { module = "hello"
  , heff = "0.4.0"
  , require =
      [{ name = "zipper", path = "github.com/you/zipper", version = "0.1.0" }]
  , replace = [{ name = "zipper", dir = "../zipper" }]
  }

require names the package, where it lives and the version hello needs. replace takes it from the directory next to hello instead, while you work on both. In src/hello/cursor.hf and app/hello/main.hf, import hello.zipper becomes import zipper.list.

$ heff build
heff build: 3 modules checked
wrote .heff/bin/hello

Installing it

$ heff install
installed ~/.heff/bin/hello
$ hello

heff install builds the program to run its fastest and puts it in ~/.heff/bin/, which is on your PATH since chapter 1.