diff --git a/+stdlib/absolute.m b/+stdlib/absolute.m
index 56bcafb..0763b80 100644
--- a/+stdlib/absolute.m
+++ b/+stdlib/absolute.m
@@ -19,14 +19,14 @@
 function c = absolute(p, base, expand_tilde, use_java)
 arguments
   p (1,1) string
-  base string {mustBeScalarOrEmpty} = string.empty
+  base (1,1) string = ""
   expand_tilde (1,1) logical = true
   use_java (1,1) logical = false
 end
 
 cwd = stdlib.posix(pwd());
 
-if (isempty(p) || strlength(p) == 0) && (isempty(base) || strlength(base) == 0)
+if strlength(p) == 0 && strlength(base) == 0
    c = cwd;
    return
 end
@@ -42,10 +42,10 @@
 else
   % .getAbsolutePath(), .toAbsolutePath()
   % default is Documents/Matlab, which is probably not wanted.
-  if isempty(base) || strlength(base) == 0
+  if strlength(base) == 0
     c = cwd + "/" + c;
   else
-    d = stdlib.absolute(base, string.empty, expand_tilde, use_java);
+    d = stdlib.absolute(base, "", expand_tilde, use_java);
     if isempty(c) || strlength(c) == 0
       c = d;
     else
diff --git a/+stdlib/h5save.m b/+stdlib/h5save.m
index 829c066..9a6e7dc 100644
--- a/+stdlib/h5save.m
+++ b/+stdlib/h5save.m
@@ -24,7 +24,7 @@ function h5save(filename, varname, A, opts)
   varname (1,1) string {mustBeNonzeroLengthText}
   A {mustBeNonempty}
   opts.size (1,:) double {mustBeInteger,mustBeNonnegative} = []
-  opts.type string {mustBeScalarOrEmpty} = string.empty
+  opts.type (1,1) string = ""
 end
 
 if isnumeric(A)
diff --git a/+stdlib/h5variables.m b/+stdlib/h5variables.m
index 07a0386..f0ae0af 100644
--- a/+stdlib/h5variables.m
+++ b/+stdlib/h5variables.m
@@ -11,10 +11,10 @@
 function names = h5variables(file, group)
 arguments
   file (1,1) string {mustBeFile}
-  group string {mustBeScalarOrEmpty} = string.empty
+  group (1,1) string = ""
 end
 
-if isempty(group) || strlength(group) == 0
+if strlength(group) == 0
   finf = h5info(file);
 else
   finf = h5info(file, group);
diff --git a/+stdlib/is_readable.m b/+stdlib/is_readable.m
index 6106a29..c947098 100644
--- a/+stdlib/is_readable.m
+++ b/+stdlib/is_readable.m
@@ -11,7 +11,7 @@
 if use_java
   % java is about 10x slower than fileattrib
   % needs absolute()
-  file = stdlib.absolute(file, string.empty, false, use_java);
+  file = stdlib.absolute(file, "", false, use_java);
 
   ok = java.nio.file.Files.isReadable(java.io.File(file).toPath());
 else
diff --git a/+stdlib/is_regular_file.m b/+stdlib/is_regular_file.m
index cad8549..e06d6b0 100644
--- a/+stdlib/is_regular_file.m
+++ b/+stdlib/is_regular_file.m
@@ -8,7 +8,7 @@
 opt = java.nio.file.LinkOption.values;
 
 % needs absolute()
-p = stdlib.absolute(p, string.empty, false, true);
+p = stdlib.absolute(p, "", false, true);
 
 isreg = java.nio.file.Files.isRegularFile(java.io.File(p).toPath(), opt);
 
diff --git a/+stdlib/is_symlink.m b/+stdlib/is_symlink.m
index 1f7379f..fd01a64 100644
--- a/+stdlib/is_symlink.m
+++ b/+stdlib/is_symlink.m
@@ -11,7 +11,7 @@
 if isMATLABReleaseOlderThan("R2024b")
   % must be absolute path
   % NOT .canonical or symlink is gobbled!
-  p = stdlib.absolute(p, string.empty, false, true);
+  p = stdlib.absolute(p, "", false, true);
   ok = java.nio.file.Files.isSymbolicLink(java.io.File(p).toPath());
 else
   ok = isSymbolicLink(p);
diff --git a/+stdlib/is_writable.m b/+stdlib/is_writable.m
index bcd1209..d1da2de 100644
--- a/+stdlib/is_writable.m
+++ b/+stdlib/is_writable.m
@@ -11,7 +11,7 @@
 if use_java
   % java is about 10x slower than fileattrib
   % needs absolute()
-  file = stdlib.absolute(file, string.empty, false, use_java);
+  file = stdlib.absolute(file, "", false, use_java);
 
   ok = java.nio.file.Files.isWritable(java.io.File(file).toPath());
 else
diff --git a/+stdlib/ncsave.m b/+stdlib/ncsave.m
index 58ba50d..a889166 100644
--- a/+stdlib/ncsave.m
+++ b/+stdlib/ncsave.m
@@ -16,7 +16,7 @@ function ncsave(filename, varname, A, opts)
   varname (1,1) string {mustBeNonzeroLengthText}
   A {mustBeNonempty}
   opts.dims cell = {}
-  opts.type string {mustBeScalarOrEmpty} = string.empty
+  opts.type (1,1) string = ""
 end
 
 if isnumeric(A)
diff --git a/+stdlib/ncvariables.m b/+stdlib/ncvariables.m
index e04277f..86293e4 100644
--- a/+stdlib/ncvariables.m
+++ b/+stdlib/ncvariables.m
@@ -11,10 +11,10 @@
 function names = ncvariables(file, group)
 arguments
   file (1,1) string {mustBeFile}
-  group string {mustBeScalarOrEmpty} = string.empty
+  group (1,1) string = ""
 end
 
-if isempty(group) || strlength(group) == 0
+if strlength(group) == 0
   finf = ncinfo(file);
 else
   finf = ncinfo(file, group);
diff --git a/+stdlib/private/coerce_ds.m b/+stdlib/private/coerce_ds.m
index a543dd6..6f47ac7 100644
--- a/+stdlib/private/coerce_ds.m
+++ b/+stdlib/private/coerce_ds.m
@@ -2,7 +2,7 @@
 % used by h5save and ncsave
 arguments
   A
-  dtype string {mustBeScalarOrEmpty}
+  dtype (1,1) string
 end
 
 if ischar(A)
@@ -10,7 +10,7 @@
   return
 end
 
-if isempty(dtype)
+if strlength(dtype) == 0
   return
 end
 
diff --git a/+stdlib/read_symlink.m b/+stdlib/read_symlink.m
index e996b54..2c98e3f 100644
--- a/+stdlib/read_symlink.m
+++ b/+stdlib/read_symlink.m
@@ -17,7 +17,7 @@
 
 % must be absolute path
 % must not be .canonical or symlink is gobbled!
-r = stdlib.absolute(p, string.empty, false, true);
+r = stdlib.absolute(p, "", false, true);
 
 % https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/nio/file/Files.html#readSymbolicLink(java.nio.file.Path)
 t = java.nio.file.Files.readSymbolicLink(java.io.File(r).toPath());
diff --git a/+stdlib/resolve.m b/+stdlib/resolve.m
index 3fcf476..079ffc0 100644
--- a/+stdlib/resolve.m
+++ b/+stdlib/resolve.m
@@ -16,6 +16,6 @@
   use_java (1,1) logical = false
 end
 
-r = stdlib.canonical(stdlib.absolute(p, string.empty, expand_tilde, use_java), false, use_java);
+r = stdlib.canonical(stdlib.absolute(p, "", expand_tilde, use_java), false, use_java);
 
 end
diff --git a/+stdlib/samepath.m b/+stdlib/samepath.m
index 47064eb..cab4555 100644
--- a/+stdlib/samepath.m
+++ b/+stdlib/samepath.m
@@ -23,8 +23,8 @@
 
 if use_java
 % needs absolute
-path1 = stdlib.absolute(path1, string.empty, false, true);
-path2 = stdlib.absolute(path2, string.empty, false, true);
+path1 = stdlib.absolute(path1, "", false, true);
+path2 = stdlib.absolute(path2, "", false, true);
 
 issame = java.nio.file.Files.isSameFile(...
             java.io.File(path1).toPath(), ...
diff --git a/+stdlib/subprocess_run.m b/+stdlib/subprocess_run.m
index 09ae018..7a714cc 100644
--- a/+stdlib/subprocess_run.m
+++ b/+stdlib/subprocess_run.m
@@ -28,15 +28,15 @@
 function [status, stdout, stderr] = subprocess_run(cmd, opt)
 arguments
   cmd (1,:) string
-  opt.env struct {mustBeScalarOrEmpty} = struct.empty
-  opt.cwd string {mustBeScalarOrEmpty} = string.empty
-  opt.stdin string {mustBeScalarOrEmpty} = string.empty
+  opt.env (1,1) struct = struct()
+  opt.cwd (1,1) string = ""
+  opt.stdin (1,1) string = ""
 end
 
 %% process instantiation
 proc = java.lang.ProcessBuilder("");
 
-if ~isempty(opt.env)
+if ~isempty(fieldnames(opt.env))
   % requires Parallel Computing Toolbox
   % https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/ProcessBuilder.html#environment()
   env = proc.environment();
@@ -46,7 +46,7 @@
   end
 end
 
-if ~isempty(opt.cwd)
+if strlength(opt.cwd) > 0
   mustBeFolder(opt.cwd)
   % https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/ProcessBuilder.html#directory(java.io.File)
   proc.directory(java.io.File(opt.cwd));
@@ -59,7 +59,7 @@
 h = proc.start();
 
 %% stdin pipe
-if ~isempty(opt.stdin)
+if strlength(opt.stdin) > 0
   writer = java.io.BufferedWriter(java.io.OutputStreamWriter(h.getOutputStream()));
   writer.write(opt.stdin);
   writer.flush()