feat: add TernaryF function (#214)

* feat: add TernaryF function

* docs: update example function to be more concise

Author: nicjohnson145

README.md

@@ -1548,6 +1548,23 @@ result := lo.Ternary[string](false, "a", "b")
 // "b"
 ```
 
+### TernaryF
+
+```go
+result := lo.TernaryF[string](true, func() string { return "a" }, func() string { return "b" })
+// "a"
+
+result := lo.TernaryF[string](false, func() string { return "a" }, func() string { return "b" })
+// "b"
+```
+
+Useful to avoid nil-pointer dereferencing in intializations, or avoid running unnecessary code
+
+```go
+var s *string
+someStr := TernaryF[string](s.Val == nil, func() string { return uuid.New().String() }, func() string { return *s })
+```
+
 ### If / ElseIf / Else
 
 ```go

condition.go

@@ -9,6 +9,14 @@ func Ternary[T any](condition bool, ifOutput T, elseOutput T) T {
 	return elseOutput
 }
 
+// TernaryF is a 1 line if/else statement whose options are functions
+func TernaryF[T any](condition bool, ifFunc func() T, elseFunc func() T) T {
+	if condition {
+		return ifFunc()
+	}
+	return elseFunc()
+}
+
 type ifElse[T any] struct {
 	result T
 	done   bool

condition_test.go

@@ -17,6 +17,16 @@ func TestTernary(t *testing.T) {
 	is.Equal(result2, "b")
 }
 
+func TestTernaryF(t *testing.T) {
+	is := assert.New(t)
+
+	result1 := TernaryF(true, func() string { return "a" }, func() string { return "b" })
+	result2 := TernaryF(false, func() string { return "a" }, func() string { return "b" })
+
+	is.Equal(result1, "a")
+	is.Equal(result2, "b")
+}
+
 func TestIfElse(t *testing.T) {
 	t.Parallel()
 	is := assert.New(t)