internal/rosa/package: migrate many libraries

This also adds more string helpers.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/state.go

@@ -477,6 +477,49 @@ func (s *S) getFrame() azalea.Frame {
 
 			// library functions
 
+			k("replace"): {F: func(
+				args azalea.FArgs,
+			) (v any, set bool, err error) {
+				var _s, _old, _new string
+				var n int
+				if err = args.Apply(map[unique.Handle[azalea.Ident]]any{
+					k("s"):   &_s,
+					k("old"): &_old,
+					k("new"): &_new,
+					k("n"):   &n,
+				}); err != nil {
+					return
+				}
+
+				if n < 0 {
+					n = 0
+				} else if n == 0 {
+					n = -1
+				}
+
+				v = strings.Replace(_s, _old, _new, n)
+				set = true
+				return
+			}},
+
+			k("slice"): {F: func(
+				args azalea.FArgs,
+			) (v any, set bool, err error) {
+				var elems []string
+				var start, end int64
+				if err = args.Apply(map[unique.Handle[azalea.Ident]]any{
+					k("elems"): &elems,
+					k("start"): &start,
+					k("end"):   &end,
+				}); err != nil {
+					return
+				}
+
+				v = elems[start:end]
+				set = true
+				return
+			}},
+
 			k("join"): {F: func(
 				args azalea.FArgs,
 			) (v any, set bool, err error) {