diff --git a/grow/definition.go b/grow/definition.go
index f23a717..2024cb6 100644
--- a/grow/definition.go
+++ b/grow/definition.go
@@ -76,7 +76,7 @@ func (def *Definition) Grow(statusChan chan<- Status) (*vm.Program, error) {
 
 		Mutate(def, prog)
 
-		scores, err := def.score(prog)
+		scores, err := def.Score(prog)
 		if err != nil {
 			// Can never get best score
 			continue
@@ -104,23 +104,7 @@ func (def *Definition) Grow(statusChan chan<- Status) (*vm.Program, error) {
 	}
 }
 
-func (def *Definition) buildSampleRanks() {
-	for col := 0; col < len(def.Samples[0].Out); col++ {
-		rank := []int{}
-
-		for i := 0; i < len(def.Samples); i++ {
-			rank = append(rank, i)
-		}
-
-		sort.SliceStable(rank, func(i, j int) bool {
-			return def.Samples[i].Out[col] < def.Samples[j].Out[col]
-		})
-
-		def.SampleRanks = append(def.SampleRanks, rank)
-	}
-}
-
-func (def *Definition) score(prog *vm.Program) ([]*Score, error) {
+func (def *Definition) GetOutputs(prog *vm.Program) ([][]uint64, error) {
 	outputs := [][]uint64{}
 
 	for _, sample := range def.Samples {
@@ -144,16 +128,25 @@ func (def *Definition) score(prog *vm.Program) ([]*Score, error) {
 		outputs = append(outputs, output)
 	}
 
+	return outputs, nil
+}
+
+func (def *Definition) Score(prog *vm.Program) ([]*Score, error) {
+	outputs, err := def.GetOutputs(prog)
+	if err != nil {
+		return nil, err
+	}
+
 	// TODO: Points for proximity to target values?
 	// TODO: Points for correlation coeficient with target values across samples?
 
 	return []*Score{
-		def.scoreMatching(outputs),
-		def.scoreRank(outputs),
+		def.ScoreMatching(outputs),
+		def.ScoreRank(outputs),
 	}, nil
 }
 
-func (def *Definition) scoreMatching(outputs [][]uint64) *Score {
+func (def *Definition) ScoreMatching(outputs [][]uint64) *Score {
 	ret := &Score{}
 
 	for s, sample := range def.Samples {
@@ -169,7 +162,7 @@ func (def *Definition) scoreMatching(outputs [][]uint64) *Score {
 	return ret
 }
 
-func (def *Definition) scoreRank(outputs [][]uint64) *Score {
+func (def *Definition) ScoreRank(outputs [][]uint64) *Score {
 	ranks := [][]int{}
 
 	for col := 0; col < len(outputs[0]); col++ {
@@ -201,6 +194,22 @@ func (def *Definition) scoreRank(outputs [][]uint64) *Score {
 	return ret
 }
 
+func (def *Definition) buildSampleRanks() {
+	for col := 0; col < len(def.Samples[0].Out); col++ {
+		rank := []int{}
+
+		for i := 0; i < len(def.Samples); i++ {
+			rank = append(rank, i)
+		}
+
+		sort.SliceStable(rank, func(i, j int) bool {
+			return def.Samples[i].Out[col] < def.Samples[j].Out[col]
+		})
+
+		def.SampleRanks = append(def.SampleRanks, rank)
+	}
+}
+
 func (def *Definition) scoreIsBetter(old, new []*Score) bool {
 	if old == nil {
 		return true
@@ -247,7 +256,7 @@ func (def *Definition) minifyProgram(prog *vm.Program) error {
 }
 
 func (def *Definition) minifyFunction(prog *vm.Program, f int) error {
-	baseScores, err := def.score(prog)
+	baseScores, err := def.Score(prog)
 	if err != nil {
 		return err
 	}
@@ -262,7 +271,7 @@ func (def *Definition) minifyFunction(prog *vm.Program, f int) error {
 			copy(tmp, prog.Functions[f].Instructions)
 			prog.Functions[f].Instructions = append(tmp[:i], tmp[i+1:]...)
 
-			newScores, err := def.score(prog)
+			newScores, err := def.Score(prog)
 			// XXX: Use all scores
 			if err == nil && newScores[0].Current >= baseScores[0].Current {
 				loop = true
diff --git a/grow/fit/config.go b/grow/fit/config.go
new file mode 100644
index 0000000..da5de55
--- /dev/null
+++ b/grow/fit/config.go
@@ -0,0 +1,10 @@
+package main
+
+import "github.com/firestuff/subcoding/grow"
+import "github.com/firestuff/subcoding/vm"
+
+type Config struct {
+	Definition *grow.Definition `yaml:"definition"`
+
+	Programs map[string]*vm.Program `yaml:"programs"`
+}
diff --git a/grow/fit/main.go b/grow/fit/main.go
new file mode 100644
index 0000000..434b550
--- /dev/null
+++ b/grow/fit/main.go
@@ -0,0 +1,13 @@
+package main
+
+import "flag"
+import "log"
+
+func main() {
+	confPath := flag.String("conf-path", "", "path to config YAML file")
+	flag.Parse()
+
+	if *confPath == "" {
+		log.Fatal("Please specify --conf-path")
+	}
+}