make more use of generics

vendor/github.com/samber/lo/condition.go

@@ -0,0 +1,99 @@
+package lo
+
+// Ternary is a 1 line if/else statement.
+func Ternary[T any](condition bool, ifOutput T, elseOutput T) T {
+	if condition {
+		return ifOutput
+	}
+
+	return elseOutput
+}
+
+type ifElse[T any] struct {
+	result T
+	done   bool
+}
+
+// If.
+func If[T any](condition bool, result T) *ifElse[T] {
+	if condition {
+		return &ifElse[T]{result, true}
+	}
+
+	var t T
+	return &ifElse[T]{t, false}
+}
+
+// ElseIf.
+func (i *ifElse[T]) ElseIf(condition bool, result T) *ifElse[T] {
+	if !i.done && condition {
+		i.result = result
+		i.done = true
+	}
+
+	return i
+}
+
+// Else.
+func (i *ifElse[T]) Else(result T) T {
+	if i.done {
+		return i.result
+	}
+
+	return result
+}
+
+type switchCase[T comparable, R any] struct {
+	predicate T
+	result    R
+	done      bool
+}
+
+// Switch is a pure functional switch/case/default statement.
+func Switch[T comparable, R any](predicate T) *switchCase[T, R] {
+	var result R
+
+	return &switchCase[T, R]{
+		predicate,
+		result,
+		false,
+	}
+}
+
+// Case.
+func (s *switchCase[T, R]) Case(val T, result R) *switchCase[T, R] {
+	if !s.done && s.predicate == val {
+		s.result = result
+		s.done = true
+	}
+
+	return s
+}
+
+// CaseF.
+func (s *switchCase[T, R]) CaseF(val T, cb func() R) *switchCase[T, R] {
+	if !s.done && s.predicate == val {
+		s.result = cb()
+		s.done = true
+	}
+
+	return s
+}
+
+// Default.
+func (s *switchCase[T, R]) Default(result R) R {
+	if !s.done {
+		s.result = result
+	}
+
+	return s.result
+}
+
+// DefaultF.
+func (s *switchCase[T, R]) DefaultF(cb func() R) R {
+	if !s.done {
+		s.result = cb()
+	}
+
+	return s.result
+}