fix: remove slices dependency to better support Go 1.20

adapters/humaflow/flow/flow.go

@@ -64,10 +64,25 @@ import (
 	"net/http"
 	"net/url"
 	"regexp"
-	"slices"
 	"strings"
 )
 
+// slicesIndex returns the index of the first occurrence of v in s,
+// or -1 if not present.
+func slicesIndex[E comparable](s []E, v E) int {
+	for i := range s {
+		if v == s[i] {
+			return i
+		}
+	}
+	return -1
+}
+
+// slicesContains reports whether v is present in s.
+func slicesContains[E comparable](s []E, v E) bool {
+	return slicesIndex(s, v) >= 0
+}
+
 // AllMethods is a slice containing all HTTP request methods.
 var AllMethods = []string{http.MethodGet, http.MethodHead, http.MethodPost, http.MethodPut, http.MethodPatch, http.MethodDelete, http.MethodConnect, http.MethodOptions, http.MethodTrace}
 
@@ -113,7 +128,7 @@ func New() *Mux {
 // Handle registers a new handler for the given request path pattern and HTTP
 // methods.
 func (m *Mux) Handle(pattern string, handler http.Handler, methods ...string) {
-	if slices.Contains(methods, http.MethodGet) && !slices.Contains(methods, http.MethodHead) {
+	if slicesContains(methods, http.MethodGet) && !slicesContains(methods, http.MethodHead) {
 		methods = append(methods, http.MethodHead)
 	}
 
@@ -176,7 +191,7 @@ func (m *Mux) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 				route.handler.ServeHTTP(w, r.WithContext(ctx))
 				return
 			}
-			if !slices.Contains(allowedMethods, route.method) {
+			if !slicesContains(allowedMethods, route.method) {
 				allowedMethods = append(allowedMethods, route.method)
 			}
 		}

formdata.go

@@ -6,7 +6,6 @@ import (
 	"mime/multipart"
 	"net/http"
 	"reflect"
-	"slices"
 	"strings"
 )
 
@@ -55,19 +54,22 @@ func (v MimeTypeValidator) Validate(fh *multipart.FileHeader, location string) (
 		file.Seek(int64(0), io.SeekStart)
 		mimeType = http.DetectContentType(buffer)
 	}
-	accept := slices.ContainsFunc(v.accept, func(m string) bool {
+	accept := false
+	for _, m := range v.accept {
 		if m == "text/plain" || m == "application/octet-stream" {
-			return true
+			accept = true
+			break
 		}
 		if strings.HasSuffix(m, "/*") &&
 			strings.HasPrefix(mimeType, strings.TrimRight(m, "*")) {
-			return true
+			accept = true
+			break
 		}
 		if mimeType == m {
-			return true
+			accept = true
+			break
 		}
-		return false
-	})
+	}
 
 	if accept {
 		return mimeType, nil
@@ -178,7 +180,7 @@ func (m *MultipartFormFiles[T]) Decode(opMediaType *MediaType) []error {
 		case field.Type() == reflect.TypeOf([]FormFile{}):
 			files, errs := m.readMultipleFiles(key, opMediaType)
 			if errs != nil {
-				errors = slices.Concat(errors, errs)
+				errors = append(errors, errs...)
 				continue
 			}
 			field.Set(reflect.ValueOf(files))