Functional Pipes in Go

pipe.go

package pipe

// Op is the common pipe operation. Can be composed into Ops and run as a single unit
type Op interface {
	Do() error
}

// OpFunc makes it easy to wrap an anonymous function into an Op
type OpFunc func() error

// Do implements the Op interface
func (o OpFunc) Do() error {
	return o()
}

// Ops can run a slice of Op's in series, stopping on the first error
type Ops []Op

// Do implements the Op interface
func (ops Ops) Do() error {
	for _, op := range ops {
		if err := op.Do(); err != nil {
			return err
		}
	}
	return nil
}

// OpFuncs makes it easy to wrap a slice of functions into an Op
type OpFuncs []func() error

// Do implements the Op interface
func (ops OpFuncs) Do() error {
	for _, op := range ops {
		if err := op(); err != nil {
			return err
		}
	}
	return nil
}

vcs.go

import (
	"gopkg.in/src-d/go-git.v4"
	"gopkg.in/src-d/go-git.v4/plumbing"
	"gopkg.in/src-d/go-git.v4/plumbing/object"

	"github.com/johnstarich/sage/pipe"
)

func initVCS(path string) (*git.Repository, error) {
	var err error
	var repo *git.Repository
	var tree *git.Worktree
	var status git.Status
	return repo, pipe.OpFuncs{
		func() error {
			repo, err = git.PlainInit(path, false)
			return err
		},
		func() error {
			tree, err = repo.Worktree()
			return err
		},
		func() error {
			status, err = tree.Status()
			return err
		},
		func() error {
			var ops pipe.OpFuncs
			added := false
			for file, stat := range status {
				// add any untracked files, excluding hidden and tmp files
				if stat.Worktree == git.Untracked && !strings.HasPrefix(file, ".") && !strings.HasSuffix(file, ".tmp") {
					fileCopy := file
					ops = append(ops, func() error {
						_, err := tree.Add(fileCopy)
						return err
					})
					added = true
				}
			}
			if added {
				ops = append(ops, func() error {
					_, err := tree.Commit("Initial commit", &git.CommitOptions{
						Author: &object.Signature{
							Name: "Sage",
							When: time.Now(),
						},
					})
return err
				})
			}
			return ops.Do()
		},
	}.Do()
}