diff --git a/+stdlib/+fileio/absolute_path.m b/+stdlib/+fileio/absolute_path.m
index 74eead2..2385f1a 100644
--- a/+stdlib/+fileio/absolute_path.m
+++ b/+stdlib/+fileio/absolute_path.m
@@ -1,13 +1,13 @@
 function abspath = absolute_path(p)
 % https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/io/File.html#getAbsolutePath()
 arguments
-  p string {mustBeScalarOrEmpty}
+  p (1,1) string
 end
 
 % have to expand ~ first (like C++ filesystem::path::absolute)
 abspath = stdlib.fileio.expanduser(p);
 
-if isempty(abspath) || abspath == ""
+if abspath == ""
   return
 end
 
@@ -21,6 +21,6 @@
   abspath = stdlib.fileio.join(pwd, abspath);
 end
 
-abspath = stdlib.posix(java.io.File(abspath).getAbsolutePath());
+abspath = stdlib.fileio.posix(java.io.File(abspath).getAbsolutePath());
 
 end % function
diff --git a/+stdlib/+fileio/canonical.m b/+stdlib/+fileio/canonical.m
index d488bee..2680bd7 100644
--- a/+stdlib/+fileio/canonical.m
+++ b/+stdlib/+fileio/canonical.m
@@ -1,16 +1,12 @@
 function c = canonical(p)
 % https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/io/File.html#getCanonicalPath()
 arguments
-  p string {mustBeScalarOrEmpty}
+  p (1,1) string
 end
 
 % have to expand ~ first (like C++ filesystem::path::absolute)
 c = stdlib.fileio.expanduser(p);
 
-if isempty(c)
-  return
-end
-
 if ispc && startsWith(c, "\\")
   % UNC path is not canonicalized
   return
diff --git a/+stdlib/+fileio/expanduser.m b/+stdlib/+fileio/expanduser.m
index fbf5ddd..c3746b2 100644
--- a/+stdlib/+fileio/expanduser.m
+++ b/+stdlib/+fileio/expanduser.m
@@ -1,7 +1,7 @@
 function e = expanduser(p)
 
 arguments
-  p string {mustBeScalarOrEmpty}
+  p (1,1) string
 end
 
 e = p;
diff --git a/+stdlib/+fileio/filename.m b/+stdlib/+fileio/filename.m
index 0cb10d6..c3ecbb1 100644
--- a/+stdlib/+fileio/filename.m
+++ b/+stdlib/+fileio/filename.m
@@ -1,7 +1,7 @@
 function p = filename(path)
 % FILENAME filename (including suffix) without directory
 arguments
-  path string
+  path (1,1) string
 end
 
 % NOT https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/io/File.html#getName()
diff --git a/+stdlib/+fileio/is_absolute_path.m b/+stdlib/+fileio/is_absolute_path.m
index c0af56d..bc16fa4 100644
--- a/+stdlib/+fileio/is_absolute_path.m
+++ b/+stdlib/+fileio/is_absolute_path.m
@@ -1,12 +1,7 @@
 function isabs = is_absolute_path(apath)
 % https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/io/File.html#isAbsolute()
 arguments
-  apath string {mustBeScalarOrEmpty}
-end
-
-if isempty(apath)
-  isabs = logical.empty();
-  return
+  apath (1,1) string
 end
 
 % expanduser() here to work like C++ filesystem::path::is_absolute()
diff --git a/+stdlib/+fileio/is_exe.m b/+stdlib/+fileio/is_exe.m
index 3aa8779..fcf7b4c 100644
--- a/+stdlib/+fileio/is_exe.m
+++ b/+stdlib/+fileio/is_exe.m
@@ -3,12 +3,7 @@
 % https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/io/File.html#canExecute()
 
 arguments
-  file string {mustBeScalarOrEmpty}
-end
-
-if isempty(file)
-  ok = logical.empty;
-  return
+  file (1,1) string
 end
 
 ok = java.io.File(file).canExecute();
diff --git a/+stdlib/+fileio/is_readable.m b/+stdlib/+fileio/is_readable.m
index 0325938..2c0f144 100644
--- a/+stdlib/+fileio/is_readable.m
+++ b/+stdlib/+fileio/is_readable.m
@@ -3,12 +3,7 @@
 % https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/nio/file/Files.html#isReadable(java.nio.file.Path)
 
 arguments
-  file string {mustBeScalarOrEmpty}
-end
-
-if isempty(file)
-  ok = logical.empty;
-  return
+  file (1,1) string
 end
 
 
diff --git a/+stdlib/+fileio/is_writable.m b/+stdlib/+fileio/is_writable.m
index 65d8211..fb50712 100644
--- a/+stdlib/+fileio/is_writable.m
+++ b/+stdlib/+fileio/is_writable.m
@@ -3,15 +3,9 @@
 % https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/nio/file/Files.html#isWritable(java.nio.file.Path)
 
 arguments
-  file string {mustBeScalarOrEmpty}
+  file (1,1) string
 end
 
-if isempty(file)
-  ok = logical.empty;
-  return
-end
-
-
 ok = java.nio.file.Files.isWritable(java.io.File(stdlib.fileio.absolute_path(file)).toPath());
 
 end
diff --git a/+stdlib/+fileio/join.m b/+stdlib/+fileio/join.m
index 78eabb3..10224f4 100644
--- a/+stdlib/+fileio/join.m
+++ b/+stdlib/+fileio/join.m
@@ -1,8 +1,8 @@
 function p = join(a, b)
 %% JOIN: join two paths with posix file separator
 arguments
-  a string {mustBeScalarOrEmpty}
-  b string {mustBeScalarOrEmpty}
+  a (1,1) string
+  b (1,1) string
 end
 
 p = stdlib.fileio.posix(fullfile(a, b));
diff --git a/+stdlib/+fileio/normalize.m b/+stdlib/+fileio/normalize.m
index a1dd25e..7ffa780 100644
--- a/+stdlib/+fileio/normalize.m
+++ b/+stdlib/+fileio/normalize.m
@@ -2,14 +2,9 @@
 % normalize(p) remove redundant elements of path p
 % https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/nio/file/Path.html#normalize()
 arguments
-  p string {mustBeScalarOrEmpty}
+  p (1,1) string
 end
 
-n = p;
-if isempty(p)
-  return
-end
-
-n = stdlib.fileio.posix(java.io.File(stdlib.fileio.expanduser(n)).toPath().normalize());
+n = stdlib.fileio.posix(java.io.File(stdlib.fileio.expanduser(p)).toPath().normalize());
 
 end
diff --git a/+stdlib/+fileio/parent.m b/+stdlib/+fileio/parent.m
index f9c5eed..94cf3cf 100644
--- a/+stdlib/+fileio/parent.m
+++ b/+stdlib/+fileio/parent.m
@@ -2,10 +2,15 @@
 % PARENT parent directory of path
 % https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/io/File.html#getParent()
 arguments
-  path string
+  path (1,1) string
 end
 
-p = stdlib.fileio.posix(java.io.File(path).getParent());
+jp = java.io.File(path).getParent();
+if isempty(jp)
+  jp = "";
+end
+
+p = stdlib.fileio.posix(jp);
 
 % must drop trailing slash - need to as_posix for windows
 %p = fileparts(strip(stdlib.fileio.posix(path), 'right', '/'));
diff --git a/+stdlib/+fileio/resolve.m b/+stdlib/+fileio/resolve.m
index d769e27..7971eb8 100644
--- a/+stdlib/+fileio/resolve.m
+++ b/+stdlib/+fileio/resolve.m
@@ -2,16 +2,12 @@
 % distinct from canonical(), resolve() always returns absolute path
 % non-existant path is made absolute relative to pwd
 arguments
-  p string {mustBeScalarOrEmpty}
+  p (1,1) string
 end
 
 % have to expand ~ first (like C++ filesystem::path::absolute)
 c = stdlib.fileio.expanduser(p);
 
-if isempty(c)
-  return
-end
-
 if ispc && startsWith(c, "\\")
   % UNC path is not canonicalized
   return
diff --git a/+stdlib/+fileio/samepath.m b/+stdlib/+fileio/samepath.m
index 63fd2e2..b972fa6 100644
--- a/+stdlib/+fileio/samepath.m
+++ b/+stdlib/+fileio/samepath.m
@@ -1,13 +1,8 @@
 function issame = samepath(path1, path2)
 % https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/nio/file/Files.html#isSameFile(java.nio.file.Path,java.nio.file.Path)
 arguments
-  path1 string {mustBeScalarOrEmpty}
-  path2 string {mustBeScalarOrEmpty}
-end
-
-if isempty(path1) || isempty(path2)
-   issame = logical.empty;
-   return
+  path1 (1,1) string
+  path2 (1,1) string
 end
 
 % java.nio.file.Files needs CANONICAL -- not just absolute path
diff --git a/+stdlib/+fileio/with_suffix.m b/+stdlib/+fileio/with_suffix.m
index deb770c..0e8a5ce 100644
--- a/+stdlib/+fileio/with_suffix.m
+++ b/+stdlib/+fileio/with_suffix.m
@@ -1,7 +1,7 @@
 function filename = with_suffix(filename, suffix)
 
 arguments
-  filename string {mustBeScalarOrEmpty}
+  filename (1,1) string
   suffix (1,1) string
 end
 
diff --git a/+stdlib/absolute_path.m b/+stdlib/absolute_path.m
index 4b1cad0..17b52ef 100644
--- a/+stdlib/absolute_path.m
+++ b/+stdlib/absolute_path.m
@@ -12,7 +12,7 @@
 % * a: absolute path, if determined
 
 arguments
-  p string {mustBeScalarOrEmpty}
+  p (1,1) string
 end
 
 a = stdlib.fileio.absolute_path(p);
diff --git a/+stdlib/canonical.m b/+stdlib/canonical.m
index cd1d18c..1ba238b 100644
--- a/+stdlib/canonical.m
+++ b/+stdlib/canonical.m
@@ -15,7 +15,7 @@
 % * c: canonical path, if determined
 
 arguments
-  p string {mustBeScalarOrEmpty}
+  p (1,1) string
 end
 
 c = stdlib.fileio.canonical(p);
diff --git a/+stdlib/expanduser.m b/+stdlib/expanduser.m
index 38ab96b..4e666c0 100644
--- a/+stdlib/expanduser.m
+++ b/+stdlib/expanduser.m
@@ -2,8 +2,7 @@
 %% expanduser(path)
 % expands tilde ~ into user home directory
 %
-% Useful for Matlab functions like h5read() and some Computer Vision toolbox functions
-% that can't handle ~
+% Useful for Matlab functions that can't handle ~
 %
 %%% Inputs
 % * p: path to expand, if tilde present
@@ -11,7 +10,7 @@
 % * expanded: expanded path
 
 arguments
-  p string
+  p (1,1) string
 end
 
 expanded = stdlib.fileio.expanduser(p);
diff --git a/+stdlib/extract_zstd.m b/+stdlib/extract_zstd.m
index 364252c..46304d9 100644
--- a/+stdlib/extract_zstd.m
+++ b/+stdlib/extract_zstd.m
@@ -7,7 +7,7 @@ function extract_zstd(archive, out_dir)
 
 arguments
   archive (1,1) string {mustBeFile}
-  out_dir (1,1) string
+  out_dir (1,1) string {mustBeFolder}
 end
 
 
diff --git a/+stdlib/filename.m b/+stdlib/filename.m
index 891d0bb..f3f92ef 100644
--- a/+stdlib/filename.m
+++ b/+stdlib/filename.m
@@ -1,7 +1,7 @@
 function p = filename(path)
 % FILENAME filename (including suffix) without directory
 arguments
-  path string
+  path (1,1) string
 end
 
 p = stdlib.fileio.filename(path);
diff --git a/+stdlib/is_absolute_path.m b/+stdlib/is_absolute_path.m
index 0ee88c1..f91326a 100644
--- a/+stdlib/is_absolute_path.m
+++ b/+stdlib/is_absolute_path.m
@@ -6,7 +6,7 @@
 %  os.path.isabs("/foo/../bar") == True
 
 arguments
-  apath string {mustBeScalarOrEmpty}
+  apath (1,1) string
 end
 
 isabs = stdlib.fileio.is_absolute_path(apath);
diff --git a/+stdlib/is_exe.m b/+stdlib/is_exe.m
index 0ae443e..e8cac13 100644
--- a/+stdlib/is_exe.m
+++ b/+stdlib/is_exe.m
@@ -8,7 +8,7 @@
 % * ok: boolean logical
 
 arguments
-  file string {mustBeScalarOrEmpty}
+  file (1,1) string
 end
 
 ok = stdlib.fileio.is_exe(file);
diff --git a/+stdlib/join.m b/+stdlib/join.m
index 398a1d6..0e33c17 100644
--- a/+stdlib/join.m
+++ b/+stdlib/join.m
@@ -1,8 +1,8 @@
 function p = join(a, b)
 %% JOIN: join two paths with posix file separator
 arguments
-  a string {mustBeScalarOrEmpty}
-  b string {mustBeScalarOrEmpty}
+  a (1,1) string
+  b (1,1) string
 end
 
 p = stdlib.fileio.join(a, b);
diff --git a/+stdlib/normalize.m b/+stdlib/normalize.m
index adfd213..f1d1051 100644
--- a/+stdlib/normalize.m
+++ b/+stdlib/normalize.m
@@ -8,7 +8,7 @@
 % * c: normalized path
 
 arguments
-  p string {mustBeScalarOrEmpty}
+  p (1,1) string
 end
 
 c = stdlib.fileio.normalize(p);
diff --git a/+stdlib/parent.m b/+stdlib/parent.m
index fa67475..85efeac 100644
--- a/+stdlib/parent.m
+++ b/+stdlib/parent.m
@@ -1,7 +1,7 @@
 function p = parent(path)
 % PARENT parent of path
 arguments
-  path string
+  path (1,1) string
 end
 
 p = stdlib.fileio.parent(path);
diff --git a/+stdlib/posix.m b/+stdlib/posix.m
index 3c719fe..22edec2 100644
--- a/+stdlib/posix.m
+++ b/+stdlib/posix.m
@@ -1,7 +1,6 @@
 function ppath = posix(file)
 %% posix(file)
-% convert a path or sequence of path components to a Posix path separated
-% with "/" even on Windows.
+% convert a path to a Posix path separated with "/" even on Windows.
 % If Windows path also have escaping "\" this breaks
 arguments
   file string
diff --git a/+stdlib/resolve.m b/+stdlib/resolve.m
index b3880bd..3637b21 100644
--- a/+stdlib/resolve.m
+++ b/+stdlib/resolve.m
@@ -15,7 +15,7 @@
 % * c: resolved path
 
 arguments
-  p string {mustBeScalarOrEmpty}
+  p (1,1) string
 end
 
 c = stdlib.fileio.resolve(p);
diff --git a/+stdlib/samepath.m b/+stdlib/samepath.m
index c2124f6..7a7dc33 100644
--- a/+stdlib/samepath.m
+++ b/+stdlib/samepath.m
@@ -7,8 +7,8 @@
 %%% Outputs
 % issame: logical
 arguments
-  path1 string {mustBeScalarOrEmpty}
-  path2 string {mustBeScalarOrEmpty}
+  path1 (1,1) string
+  path2 (1,1) string
 end
 
 issame = stdlib.fileio.samepath(path1, path2);
diff --git a/+stdlib/with_suffix.m b/+stdlib/with_suffix.m
index de6516a..ef6f83b 100644
--- a/+stdlib/with_suffix.m
+++ b/+stdlib/with_suffix.m
@@ -7,7 +7,7 @@
 %%% Outputs
 % * filename: modified filename
 arguments
-  filename string
+  filename (1,1) string
   suffix (1,1) string
 end
 
diff --git a/test/TestFilePure.m b/test/TestFilePure.m
index 98209f2..3e6605d 100644
--- a/test/TestFilePure.m
+++ b/test/TestFilePure.m
@@ -94,6 +94,31 @@ function test_is_absolute_path(tc)
 tc.verifyFalse(stdlib.is_absolute_path("c"))
 end
 
+function test_absolute_path(tc)
+import matlab.unittest.constraints.StartsWithSubstring
+
+tc.verifyEqual(stdlib.absolute_path(""), "")
+
+pabs = stdlib.absolute_path('2foo');
+pabs2 = stdlib.absolute_path('4foo');
+tc.verifyThat(pabs, ~StartsWithSubstring("2"))
+tc.verifyTrue(strncmp(pabs, pabs2, 2))
+
+par1 = stdlib.absolute_path("../2foo");
+tc.verifyNotEmpty(par1)
+
+par2 = stdlib.absolute_path("../4foo");
+tc.verifyTrue(strncmp(par2, pabs2, 2))
+
+pt1 = stdlib.absolute_path("bar/../2foo");
+tc.verifyNotEmpty(pt1)
+
+va = stdlib.absolute_path("2foo");
+vb = stdlib.absolute_path("4foo");
+tc.verifyThat(va, ~StartsWithSubstring("2"))
+tc.verifyTrue(strncmp(va, vb, 2))
+
+end
 
 function test_normalize(tc)