diff --git a/R/function.R b/R/function.R
index 8e4d8e0..425a5bb 100644
--- a/R/function.R
+++ b/R/function.R
@@ -63,6 +63,14 @@ ts_result <- function(type, value) {
 #' @param result return type (ignored if overloads are provided)
 #' @export
 #' @md
+#'
+#' @return a ts function object which has a `call` method that will call the function with the given arguments, which will be checked for type correctness.
+#'
+#' @examples
+#' f <- ts_function(function(x = ts_integer(1), y = ts_character(1)) {
+#'     x + nchar(y)
+#' }, result = ts_integer(1))
+#' f$call(1, "hello")
 ts_function <- function(f, ..., result = ts_void()) {
     args <- list(...)
     if (!is.null(result) && !is_ts_object(result)) {
@@ -117,9 +125,19 @@ print.ts_function <- function(x, ...) {
 #' Anything that is not a function simply returns itself.
 #' However, functions are wrapped with `Rserve::ocap()`,
 #' and the result is subsequently wrapped with `ts_app()`.
+#'
 #' @param x A ts function object (`ts_function()`)
 #' @export
 #' @md
+#'
+#' @returns An object of class 'OCref', see [Rserve::ocap()]
+#'
+#' @examples
+#' f <- ts_function(function(x = ts_integer(1), y = ts_character(1)) {
+#'     x + nchar(y)
+#' }, result = ts_integer(1))
+#' app <- ts_app(f) # class of 'OCref'
+#' # this can now be used in an Rserve application, for example
 ts_app <- function(x) UseMethod("ts_app")
 
 #' @export
diff --git a/R/types.R b/R/types.R
index 4605d54..d539ca7 100644
--- a/R/types.R
+++ b/R/types.R
@@ -1,4 +1,4 @@
-#' Typed object
+#' Typed object (internal use only)
 #'
 #' This is the base type for all typed objects, and can be used to define
 #' custom types.
@@ -115,9 +115,11 @@ check_type.ts_function <- function(type, x) {
 #' Union type
 #'
 #' Create a union of types. Currently this only accepts schemas as strings.
-#' @param ... Types to merge
+#' @param ... Zod types to merge (as strings)
 #' @export
 #' @md
+#' @examples
+#' x <- ts_union("z.number()", "z.string()")
 ts_union <- function(...) sprintf("z.union([%s])", paste(..., sep = ", "))
 
 ts_array <- function(type = c("z.number()", "z.boolean()", "z.string()")) {
@@ -157,6 +159,7 @@ n_type_fun <- function(n, type) {
 #' x$check(TRUE)
 #'
 #' \dontrun{
+#' # this will fail
 #' x$check(5)
 #' }
 ts_logical <- function(n = -1L) {
@@ -182,6 +185,14 @@ ts_logical <- function(n = -1L) {
 #' @return A ts object that accepts integer scalars or vectors of length `n`.
 #' @export
 #' @md
+#' @examples
+#' x <- ts_integer(1)
+#' x$check(1L)
+#'
+#' \dontrun{
+#' # this will fail
+#' x$check(1:10)
+#' }
 ts_integer <- function(n = -1L) {
     ts_object(
         n_type(n, "z.number()", "z.instanceof(Int32Array)"),
@@ -209,6 +220,15 @@ ts_integer <- function(n = -1L) {
 #' @return A ts object that accepts numeric scalars or vectors of length `n`.
 #' @export
 #' @md
+#' @examples
+#' x <- ts_numeric(1)
+#' x$check(1)
+#'
+#' \dontrun{
+#' # this will fail
+#' x$check(c(1, 2, 3))
+#' x$check("a")
+#' }
 ts_numeric <- function(n = -1L) {
     ts_object(
         n_type(n, "z.number()"),
@@ -231,6 +251,9 @@ ts_numeric <- function(n = -1L) {
 #' @return A ts object that accepts strings or string vectors of length `n`.
 #' @export
 #' @md
+#' @examples
+#' x <- ts_character(1)
+#' x$check("a")
 ts_character <- function(n = -1L) {
     ts_object(
         n_type(n, "z.string()"),
@@ -256,6 +279,15 @@ vector_as_ts_array <- function(x) {
 #'
 #' @export
 #' @md
+#' @examples
+#' x <- ts_factor(levels = c("a", "b"))
+#' x$check(factor("a", levels = c("a", "b")))
+#'
+#' \dontrun{
+#' # this will fail
+#' x$check("a")
+#' x$check(factor("c", levels = c("a", "b", "c")))
+#' }
 ts_factor <- function(levels = NULL) {
     ts_object(
         ifelse(is.null(levels),
@@ -290,6 +322,10 @@ ts_factor <- function(levels = NULL) {
 #'
 #' @export
 #' @md
+#'
+#' @examples
+#' x <- ts_list(a = ts_integer(1), b = ts_character(1))
+#' x$check(list(a = 1L, b = "a"))
 ts_list <- function(...) {
     values <- list(...)
 
@@ -348,6 +384,10 @@ ts_list <- function(...) {
 #'
 #' @export
 #' @md
+#'
+#' @examples
+#' x <- ts_dataframe(a = ts_integer(1), b = ts_character(1))
+#' x$check(data.frame(a = 1L, b = "a"))
 ts_dataframe <- function(...) {
     values <- list(...)
     type <- "z.record(z.string(), z.any())"
@@ -379,11 +419,15 @@ ts_dataframe <- function(...) {
 
 #' Null type
 #'
-#' This is a type that only accepts `NULL`.
+#' This is a type that only accepts `NULL`. For function return types, use `ts_void`.
 #'
 #' @return A ts object that only accepts `NULL`.
 #' @export
 #'
+#' @md
+#' @examples
+#' x <- ts_null()
+#' x$check(NULL)
 ts_null <- function() {
     ts_object(
         "z.null()",
@@ -402,6 +446,7 @@ ts_null <- function() {
 #' @return A ts object that accepts `NULL`.
 #' @export
 #' @md
+#' @seealso \code{\link{ts_null}}
 ts_void <- function() {
     ts_object(
         "z.void()",
diff --git a/man/ts_app.Rd b/man/ts_app.Rd
index 3cf8c66..9addebe 100644
--- a/man/ts_app.Rd
+++ b/man/ts_app.Rd
@@ -9,8 +9,18 @@ ts_app(x)
 \arguments{
 \item{x}{A ts function object (\code{ts_function()})}
 }
+\value{
+An object of class 'OCref', see \code{\link[Rserve:ocap]{Rserve::ocap()}}
+}
 \description{
 Anything that is not a function simply returns itself.
 However, functions are wrapped with \code{Rserve::ocap()},
 and the result is subsequently wrapped with \code{ts_app()}.
 }
+\examples{
+f <- ts_function(function(x = ts_integer(1), y = ts_character(1)) {
+    x + nchar(y)
+}, result = ts_integer(1))
+app <- ts_app(f) # class of 'OCref'
+# this can now be used in an Rserve application, for example
+}
diff --git a/man/ts_character.Rd b/man/ts_character.Rd
index f18322f..425f35b 100644
--- a/man/ts_character.Rd
+++ b/man/ts_character.Rd
@@ -16,3 +16,7 @@ A ts object that accepts strings or string vectors of length \code{n}.
 Strings are represented in Zod schema as either a string (\code{z.string()}),
 or a string array (\code{z.array(z.string())}).
 }
+\examples{
+x <- ts_character(1)
+x$check("a")
+}
diff --git a/man/ts_dataframe.Rd b/man/ts_dataframe.Rd
index eef97b1..d9a895a 100644
--- a/man/ts_dataframe.Rd
+++ b/man/ts_dataframe.Rd
@@ -15,3 +15,7 @@ A ts object that accepts data frames with the specified types.
 \description{
 This is essentially a list, but the elements must have names and are all the same length.
 }
+\examples{
+x <- ts_dataframe(a = ts_integer(1), b = ts_character(1))
+x$check(data.frame(a = 1L, b = "a"))
+}
diff --git a/man/ts_factor.Rd b/man/ts_factor.Rd
index eedbf24..c18e54e 100644
--- a/man/ts_factor.Rd
+++ b/man/ts_factor.Rd
@@ -15,3 +15,13 @@ A ts object that accepts factors with the specified levels.
 \description{
 Factors are integers with labels. On the JS side, these are \emph{always} represented as a string array (even if only one value - yay!).
 }
+\examples{
+x <- ts_factor(levels = c("a", "b"))
+x$check(factor("a", levels = c("a", "b")))
+
+\dontrun{
+# this will fail
+x$check("a")
+x$check(factor("c", levels = c("a", "b", "c")))
+}
+}
diff --git a/man/ts_function.Rd b/man/ts_function.Rd
index cfc890f..c76e353 100644
--- a/man/ts_function.Rd
+++ b/man/ts_function.Rd
@@ -29,3 +29,9 @@ can explicitly be defined with their types as formal arguments:
 \if{html}{\out{<div class="sourceCode">}}\preformatted{ts_function(function(x = ts_integer(), y = ts_string()) \{ ... \})
 }\if{html}{\out{</div>}}
 }
+\examples{
+f <- ts_function(function(x = ts_integer(1), y = ts_character(1)) {
+    x + nchar(y)
+}, result = ts_integer(1))
+f$call(1, "hello")
+}
diff --git a/man/ts_integer.Rd b/man/ts_integer.Rd
index 77a5063..0c6b71d 100644
--- a/man/ts_integer.Rd
+++ b/man/ts_integer.Rd
@@ -16,3 +16,12 @@ A ts object that accepts integer scalars or vectors of length \code{n}.
 Integers are represented in Zod schema as either a number (\code{z.number()}),
 or a Int32Array (\code{z.instanceof(Int32Array)}).
 }
+\examples{
+x <- ts_integer(1)
+x$check(1L)
+
+\dontrun{
+# this will fail
+x$check(1:10)
+}
+}
diff --git a/man/ts_list.Rd b/man/ts_list.Rd
index 7bfab76..7645406 100644
--- a/man/ts_list.Rd
+++ b/man/ts_list.Rd
@@ -15,3 +15,7 @@ A ts object that accepts lists with the specified types.
 \description{
 A list is a vector of other robjects, which may or may not be named.
 }
+\examples{
+x <- ts_list(a = ts_integer(1), b = ts_character(1))
+x$check(list(a = 1L, b = "a"))
+}
diff --git a/man/ts_logical.Rd b/man/ts_logical.Rd
index 29070c6..4154abf 100644
--- a/man/ts_logical.Rd
+++ b/man/ts_logical.Rd
@@ -21,6 +21,7 @@ x <- ts_logical(1)
 x$check(TRUE)
 
 \dontrun{
+# this will fail
 x$check(5)
 }
 }
diff --git a/man/ts_null.Rd b/man/ts_null.Rd
index 26a5f67..e220ed1 100644
--- a/man/ts_null.Rd
+++ b/man/ts_null.Rd
@@ -10,5 +10,9 @@ ts_null()
 A ts object that only accepts \code{NULL}.
 }
 \description{
-This is a type that only accepts \code{NULL}.
+This is a type that only accepts \code{NULL}. For function return types, use \code{ts_void}.
+}
+\examples{
+x <- ts_null()
+x$check(NULL)
 }
diff --git a/man/ts_numeric.Rd b/man/ts_numeric.Rd
index ab18d85..005fe4b 100644
--- a/man/ts_numeric.Rd
+++ b/man/ts_numeric.Rd
@@ -16,3 +16,13 @@ A ts object that accepts numeric scalars or vectors of length \code{n}.
 Numbers are represented in Zod schema as either a number (\code{z.number()}),
 or a Float64Array (\code{z.instanceof(Float64Array)}).
 }
+\examples{
+x <- ts_numeric(1)
+x$check(1)
+
+\dontrun{
+# this will fail
+x$check(c(1, 2, 3))
+x$check("a")
+}
+}
diff --git a/man/ts_object.Rd b/man/ts_object.Rd
index 10a44fb..c961da4 100644
--- a/man/ts_object.Rd
+++ b/man/ts_object.Rd
@@ -5,7 +5,7 @@
 \alias{is_ts_object}
 \alias{get_type}
 \alias{check_type}
-\title{Typed object}
+\title{Typed object (internal use only)}
 \usage{
 ts_object(
   input_type = "any",
diff --git a/man/ts_union.Rd b/man/ts_union.Rd
index 0b679ab..06614d9 100644
--- a/man/ts_union.Rd
+++ b/man/ts_union.Rd
@@ -7,8 +7,11 @@
 ts_union(...)
 }
 \arguments{
-\item{...}{Types to merge}
+\item{...}{Zod types to merge (as strings)}
 }
 \description{
 Create a union of types. Currently this only accepts schemas as strings.
 }
+\examples{
+x <- ts_union("z.number()", "z.string()")
+}
diff --git a/man/ts_void.Rd b/man/ts_void.Rd
index 6d5d40e..4aa5d7c 100644
--- a/man/ts_void.Rd
+++ b/man/ts_void.Rd
@@ -13,3 +13,6 @@ A ts object that accepts \code{NULL}.
 This is a type that accepts null values (this would typically be used for
 functions that return nothing).
 }
+\seealso{
+\code{\link{ts_null}}
+}
diff --git a/tests/testthat/test-custom-types.R b/tests/testthat/test-custom-types.R
new file mode 100644
index 0000000..cc1d601
--- /dev/null
+++ b/tests/testthat/test-custom-types.R
@@ -0,0 +1,30 @@
+hist_type <- ts_object(
+    input_type = "z.object({
+       breaks: z.array(z.number()),
+       counts: z.array(z.number()),
+       density: z.array(z.number()),
+       mids: z.array(z.number()),
+       xname: z.string(),
+       equidist: z.boolean(),
+     })",
+    return_type = "Robj.list({
+         breaks: Robj.numeric(),
+         counts: Robj.numeric(),
+         density: Robj.numeric(),
+         mids: Robj.numeric(),
+         xname: Robj.character(1),
+         equidist: Robj.logical(1),
+     })",
+    check = function(x) {
+        stopifnot(is.list(x))
+        stopifnot(all(c("breaks", "counts", "density", "mids", "xname", "equidist") %in% names(x)))
+        stopifnot(is.numeric(x$breaks))
+        stopifnot(is.numeric(x$counts))
+        stopifnot(is.numeric(x$density))
+        stopifnot(is.numeric(x$mids))
+        stopifnot(is.character(x$xname))
+        stopifnot(is.logical(x$equidist))
+        stopifnot(isTRUE(all.equal(length(x$breaks), length(x$counts), length(x$density), length(x$mids))))
+        x
+    }
+)