diff --git a/NEWS.md b/NEWS.md
index bccd13cd5..d31b3d584 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -9,6 +9,8 @@
 - New method `$clone()` for `LazyFrame` (#347).
 - `$with_column()` is now deprecated (following upstream `polars`). It will be
   removed in 0.9.0. It should be replaced with `$with_columns()` (#313).
+- New lazy function translated: `concat_str()` to concatenate several columns
+  into one (#349).
 - New stat functions `pl$cov()`, `pl$rolling_cov()` `pl$corr()`, `pl$rolling_corr()` (#351).
 
 # polars 0.7.0
diff --git a/R/dataframe__frame.R b/R/dataframe__frame.R
index 3826d2ae5..46f5e3e0a 100644
--- a/R/dataframe__frame.R
+++ b/R/dataframe__frame.R
@@ -1003,13 +1003,13 @@ DataFrame_to_list = function(unnest_structs = TRUE) {
 #' @keywords DataFrame
 #' @examples
 #' # inner join by default
-#' df1 <- pl$DataFrame(list(key = 1:3, payload = c("f", "i", NA)))
-#' df2 <- pl$DataFrame(list(key = c(3L, 4L, 5L, NA_integer_)))
+#' df1 = pl$DataFrame(list(key = 1:3, payload = c("f", "i", NA)))
+#' df2 = pl$DataFrame(list(key = c(3L, 4L, 5L, NA_integer_)))
 #' df1$join(other = df2, on = "key")
 #'
 #' # cross join
-#' df1 <- pl$DataFrame(x = letters[1:3])
-#' df2 <- pl$DataFrame(y = 1:4)
+#' df1 = pl$DataFrame(x = letters[1:3])
+#' df2 = pl$DataFrame(y = 1:4)
 #' df1$join(other = df2, how = "cross")
 #'
 DataFrame_join = function(
@@ -1560,7 +1560,6 @@ DataFrame_glimpse = function(..., return_as_string = FALSE) {
 #' df
 #'
 #' df$explode("numbers")
-
 DataFrame_explode = function(columns, ...) {
   self$lazy()$explode(columns, ...)$collect()
 }
diff --git a/R/expr__expr.R b/R/expr__expr.R
index 370b9bb53..063e740e2 100644
--- a/R/expr__expr.R
+++ b/R/expr__expr.R
@@ -3322,7 +3322,7 @@ Expr_diff = function(n = 1, null_behavior = "ignore") {
 #' @keywords Expr
 #' @examples
 #' df = pl$DataFrame(list(a = c(10L, 11L, 12L, NA_integer_, 12L)))
-#' df$with_column(pl$col("a")$pct_change()$alias("pct_change"))
+#' df$with_columns(pl$col("a")$pct_change()$alias("pct_change"))
 Expr_pct_change = function(n = 1) {
   unwrap(.pr$Expr$pct_change(self, n))
 }
@@ -3417,7 +3417,7 @@ Expr_kurtosis = function(fisher = TRUE, bias = TRUE) {
 #'
 #' @examples
 #' df = pl$DataFrame(foo = c(-50L, 5L, NA_integer_, 50L))
-#' df$with_column(pl$col("foo")$clip(1L, 10L)$alias("foo_clipped"))
+#' df$with_columns(pl$col("foo")$clip(1L, 10L)$alias("foo_clipped"))
 Expr_clip = function(min, max) {
   unwrap(.pr$Expr$clip(self, wrap_e(min), wrap_e(max)))
 }
@@ -3427,7 +3427,7 @@ Expr_clip = function(min, max) {
 #' @aliases clip_min
 #' @keywords Expr
 #' @examples
-#' df$with_column(pl$col("foo")$clip_min(1L)$alias("foo_clipped"))
+#' df$with_columns(pl$col("foo")$clip_min(1L)$alias("foo_clipped"))
 Expr_clip_min = function(min) {
   unwrap(.pr$Expr$clip_min(self, wrap_e(min)))
 }
@@ -3437,7 +3437,7 @@ Expr_clip_min = function(min) {
 #' @aliases clip_max
 #' @keywords Expr
 #' @examples
-#' df$with_column(pl$col("foo")$clip_max(10L)$alias("foo_clipped"))
+#' df$with_columns(pl$col("foo")$clip_max(10L)$alias("foo_clipped"))
 Expr_clip_max = function(max) {
   unwrap(.pr$Expr$clip_max(self, wrap_e(max)))
 }
@@ -4182,7 +4182,7 @@ Expr_list = function() {
 #'   f = c("a", "b", "c"),
 #'   g = c(0.1, 1.32, 0.12),
 #'   h = c(TRUE, NA, FALSE)
-#' )$with_column(pl$col("b")$cast(pl$Int64) * 32L)$select(pl$all()$shrink_dtype())
+#' )$with_columns(pl$col("b")$cast(pl$Int64) * 32L)$select(pl$all()$shrink_dtype())
 Expr_shrink_dtype = "use_extendr_wrapper"
 
 
@@ -4204,7 +4204,7 @@ Expr_shrink_dtype = "use_extendr_wrapper"
 #' )$agg(
 #'   pl$col("value") * 3L
 #' )
-#' df_with_list$with_column(
+#' df_with_list$with_columns(
 #'   pl$col("value")$arr$lengths()$alias("group_size")
 #' )
 Expr_arr = method_as_property(function() {
diff --git a/R/expr__list.R b/R/expr__list.R
index 72985bf64..8b9ee52d8 100644
--- a/R/expr__list.R
+++ b/R/expr__list.R
@@ -17,7 +17,7 @@
 #' @aliases lengths arr.lengths arr_lengths
 #' @examples
 #' df = pl$DataFrame(list_of_strs = pl$Series(list(c("a", "b"), "c")))
-#' df$with_column(pl$col("list_of_strs")$arr$lengths()$alias("list_of_strs_lengths"))
+#' df$with_columns(pl$col("list_of_strs")$arr$lengths()$alias("list_of_strs_lengths"))
 ExprArr_lengths = function() .pr$Expr$arr_lengths(self)
 
 #' Sum lists
@@ -415,7 +415,7 @@ ExprArr_to_struct = function(
 #' @aliases arr_eval arr.eval
 #' @examples
 #' df = pl$DataFrame(a = list(c(1, 8, 3), b = c(4, 5, 2)))
-#' df$select(pl$all()$cast(pl$dtypes$Int64))$with_column(
+#' df$select(pl$all()$cast(pl$dtypes$Int64))$with_columns(
 #'   pl$concat_list(c("a", "b"))$arr$eval(pl$element()$rank())$alias("rank")
 #' )
 ExprArr_eval = function(expr, parallel = FALSE) {
diff --git a/R/extendr-wrappers.R b/R/extendr-wrappers.R
index 04973aa1c..8f9f45e44 100644
--- a/R/extendr-wrappers.R
+++ b/R/extendr-wrappers.R
@@ -35,6 +35,8 @@ sum_exprs <- function(exprs) .Call(wrap__sum_exprs, exprs)
 
 concat_list <- function(exprs) .Call(wrap__concat_list, exprs)
 
+concat_str <- function(dotdotdot, separator) .Call(wrap__concat_str, dotdotdot, separator)
+
 r_date_range <- function(start, stop, every, closed, name, tu, tz) .Call(wrap__r_date_range, start, stop, every, closed, name, tu, tz)
 
 r_date_range_lazy <- function(start, end, every, closed, tz) .Call(wrap__r_date_range_lazy, start, end, every, closed, tz)
diff --git a/R/functions__lazy.R b/R/functions__lazy.R
index c19c48151..6ea9e8650 100644
--- a/R/functions__lazy.R
+++ b/R/functions__lazy.R
@@ -529,12 +529,12 @@ pl$approx_unique = function(column) { #-> int or Expr
 #' df = pl$DataFrame(a = 1:2, b = 3:4, c = 5:6)
 #'
 #' # column as list
-#' df$with_column(pl$sum(list("a", "c")))
-#' df$with_column(pl$sum(list("a", "c", 42L)))
+#' df$with_columns(pl$sum(list("a", "c")))
+#' df$with_columns(pl$sum(list("a", "c", 42L)))
 #'
 #' # two eqivalent lines
-#' df$with_column(pl$sum(list(pl$col("a") + pl$col("b"), "c")))
-#' df$with_column(pl$sum(list("*")))
+#' df$with_columns(pl$sum(list(pl$col("a") + pl$col("b"), "c")))
+#' df$with_columns(pl$sum(list("*")))
 pl$sum = function(...) {
   column = list2(...)
   if (length(column) == 1L) column <- column[[1L]]
@@ -576,7 +576,7 @@ pl$sum = function(...) {
 #'   d = c(1:2, NA_real_, -Inf)
 #' )
 #' # use min to get first non Null value for each row, otherwise insert 99.9
-#' df$with_column(
+#' df$with_columns(
 #'   pl$min("a", "b", "c", 99.9)$alias("d")
 #' )
 #'
@@ -623,7 +623,7 @@ pl$min = function(...) {
 #'   c = c(1:3, NA_real_)
 #' )
 #' # use coalesce to get first non Null value for each row, otherwise insert 99.9
-#' df$with_column(
+#' df$with_columns(
 #'   pl$coalesce("a", "b", "c", 99.9)$alias("d")
 #' )
 #'
@@ -669,7 +669,7 @@ pl$max = function(...) {
 #'   c = c(1:3, NA_real_)
 #' )
 #' # use coalesce to get first non Null value for each row, otherwise insert 99.9
-#' df$with_column(
+#' df$with_columns(
 #'   pl$coalesce("a", "b", "c", 99.9)$alias("d")
 #' )
 #'
@@ -845,6 +845,36 @@ pl$struct = function(
     )
 }
 
+#' Horizontally concatenate columns into a single string column
+#'
+#' @param ... Columns to concatenate into a single string column. Accepts
+#' expressions. Strings are parsed as column names, other non-expression inputs
+#' are parsed as literals. Non-Utf8 columns are cast to Utf8.
+#' @param separator String that will be used to separate the values of each
+#' column.
+#' @name pl_concat_str
+#' @return Expr
+#' @examples
+#' df = pl$DataFrame(
+#'   a = c(1, 2, 3),
+#'   b = c("dogs", "cats", NA),
+#'   c = c("play", "swim", "walk")
+#' )
+#'
+#' df$with_columns(
+#'   pl$concat_str(
+#'     pl$col("a") * 2,
+#'     "b",
+#'     "c",
+#'     pl$lit("!"),
+#'     separator = " "
+#'   )$alias("full_sentence")
+#' )
+#'
+pl$concat_str = function(..., separator = "") {
+  concat_str(list2(...), separator) |> unwrap("in $concat_str()")
+}
+
 #' Covariance
 #' @name pl_cov
 #' @description Calculates the covariance between two columns / expressions.
diff --git a/man/DataFrame_join.Rd b/man/DataFrame_join.Rd
index 86572e40c..151aaf708 100644
--- a/man/DataFrame_join.Rd
+++ b/man/DataFrame_join.Rd
@@ -40,13 +40,13 @@ join DataFrame with other DataFrame
 }
 \examples{
 # inner join by default
-df1 <- pl$DataFrame(list(key = 1:3, payload = c("f", "i", NA)))
-df2 <- pl$DataFrame(list(key = c(3L, 4L, 5L, NA_integer_)))
+df1 = pl$DataFrame(list(key = 1:3, payload = c("f", "i", NA)))
+df2 = pl$DataFrame(list(key = c(3L, 4L, 5L, NA_integer_)))
 df1$join(other = df2, on = "key")
 
 # cross join
-df1 <- pl$DataFrame(x = letters[1:3])
-df2 <- pl$DataFrame(y = 1:4)
+df1 = pl$DataFrame(x = letters[1:3])
+df2 = pl$DataFrame(y = 1:4)
 df1$join(other = df2, how = "cross")
 
 }
diff --git a/man/Expr_arr.Rd b/man/Expr_arr.Rd
index bc9119e89..027fedd15 100644
--- a/man/Expr_arr.Rd
+++ b/man/Expr_arr.Rd
@@ -24,7 +24,7 @@ df_with_list = pl$DataFrame(
 )$agg(
   pl$col("value") * 3L
 )
-df_with_list$with_column(
+df_with_list$with_columns(
   pl$col("value")$arr$lengths()$alias("group_size")
 )
 }
diff --git a/man/Expr_clip.Rd b/man/Expr_clip.Rd
index 5aa41983f..92698d4e4 100644
--- a/man/Expr_clip.Rd
+++ b/man/Expr_clip.Rd
@@ -33,8 +33,8 @@ expression. See :func:\code{when} for more information.
 }
 \examples{
 df = pl$DataFrame(foo = c(-50L, 5L, NA_integer_, 50L))
-df$with_column(pl$col("foo")$clip(1L, 10L)$alias("foo_clipped"))
-df$with_column(pl$col("foo")$clip_min(1L)$alias("foo_clipped"))
-df$with_column(pl$col("foo")$clip_max(10L)$alias("foo_clipped"))
+df$with_columns(pl$col("foo")$clip(1L, 10L)$alias("foo_clipped"))
+df$with_columns(pl$col("foo")$clip_min(1L)$alias("foo_clipped"))
+df$with_columns(pl$col("foo")$clip_max(10L)$alias("foo_clipped"))
 }
 \keyword{Expr}
diff --git a/man/Expr_pct_change.Rd b/man/Expr_pct_change.Rd
index 15df8041e..b8c04c91f 100644
--- a/man/Expr_pct_change.Rd
+++ b/man/Expr_pct_change.Rd
@@ -21,6 +21,6 @@ Computes the change from the previous row by default.
 }
 \examples{
 df = pl$DataFrame(list(a = c(10L, 11L, 12L, NA_integer_, 12L)))
-df$with_column(pl$col("a")$pct_change()$alias("pct_change"))
+df$with_columns(pl$col("a")$pct_change()$alias("pct_change"))
 }
 \keyword{Expr}
diff --git a/man/Expr_shrink_dtype.Rd b/man/Expr_shrink_dtype.Rd
index 2dda08465..c205ea542 100644
--- a/man/Expr_shrink_dtype.Rd
+++ b/man/Expr_shrink_dtype.Rd
@@ -24,6 +24,6 @@ pl$DataFrame(
   f = c("a", "b", "c"),
   g = c(0.1, 1.32, 0.12),
   h = c(TRUE, NA, FALSE)
-)$with_column(pl$col("b")$cast(pl$Int64) * 32L)$select(pl$all()$shrink_dtype())
+)$with_columns(pl$col("b")$cast(pl$Int64) * 32L)$select(pl$all()$shrink_dtype())
 }
 \keyword{Expr}
diff --git a/man/arr_eval.Rd b/man/arr_eval.Rd
index a7a0c3852..14d43edae 100644
--- a/man/arr_eval.Rd
+++ b/man/arr_eval.Rd
@@ -25,7 +25,7 @@ Run any polars expression against the lists' elements.
 }
 \examples{
 df = pl$DataFrame(a = list(c(1, 8, 3), b = c(4, 5, 2)))
-df$select(pl$all()$cast(pl$dtypes$Int64))$with_column(
+df$select(pl$all()$cast(pl$dtypes$Int64))$with_columns(
   pl$concat_list(c("a", "b"))$arr$eval(pl$element()$rank())$alias("rank")
 )
 }
diff --git a/man/arr_lengths.Rd b/man/arr_lengths.Rd
index a6a50e778..fcc138646 100644
--- a/man/arr_lengths.Rd
+++ b/man/arr_lengths.Rd
@@ -16,6 +16,6 @@ Get the length of the arrays as UInt32
 }
 \examples{
 df = pl$DataFrame(list_of_strs = pl$Series(list(c("a", "b"), "c")))
-df$with_column(pl$col("list_of_strs")$arr$lengths()$alias("list_of_strs_lengths"))
+df$with_columns(pl$col("list_of_strs")$arr$lengths()$alias("list_of_strs_lengths"))
 }
 \keyword{ExprArr}
diff --git a/man/pl_coalesce.Rd b/man/pl_coalesce.Rd
index 66c521ed1..9ea56fc05 100644
--- a/man/pl_coalesce.Rd
+++ b/man/pl_coalesce.Rd
@@ -28,7 +28,7 @@ df = pl$DataFrame(
   c = c(1:3, NA_real_)
 )
 # use coalesce to get first non Null value for each row, otherwise insert 99.9
-df$with_column(
+df$with_columns(
   pl$coalesce("a", "b", "c", 99.9)$alias("d")
 )
 
diff --git a/man/pl_concat_str.Rd b/man/pl_concat_str.Rd
new file mode 100644
index 000000000..5999332fa
--- /dev/null
+++ b/man/pl_concat_str.Rd
@@ -0,0 +1,37 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/functions__lazy.R
+\name{pl_concat_str}
+\alias{pl_concat_str}
+\title{Horizontally concatenate columns into a single string column}
+\arguments{
+\item{...}{Columns to concatenate into a single string column. Accepts
+expressions. Strings are parsed as column names, other non-expression inputs
+are parsed as literals. Non-Utf8 columns are cast to Utf8.}
+
+\item{separator}{String that will be used to separate the values of each
+column.}
+}
+\value{
+Expr
+}
+\description{
+Horizontally concatenate columns into a single string column
+}
+\examples{
+df = pl$DataFrame(
+  a = c(1, 2, 3),
+  b = c("dogs", "cats", NA),
+  c = c("play", "swim", "walk")
+)
+
+df$with_columns(
+  pl$concat_str(
+    pl$col("a") * 2,
+    "b",
+    "c",
+    pl$lit("!"),
+    separator = " "
+  )$alias("full_sentence")
+)
+
+}
diff --git a/man/pl_max.Rd b/man/pl_max.Rd
index 4034c8d09..f3b757be1 100644
--- a/man/pl_max.Rd
+++ b/man/pl_max.Rd
@@ -28,7 +28,7 @@ df = pl$DataFrame(
   c = c(1:3, NA_real_)
 )
 # use coalesce to get first non Null value for each row, otherwise insert 99.9
-df$with_column(
+df$with_columns(
   pl$coalesce("a", "b", "c", 99.9)$alias("d")
 )
 
diff --git a/man/pl_min.Rd b/man/pl_min.Rd
index d3159ac51..34b8b985a 100644
--- a/man/pl_min.Rd
+++ b/man/pl_min.Rd
@@ -29,7 +29,7 @@ df = pl$DataFrame(
   d = c(1:2, NA_real_, -Inf)
 )
 # use min to get first non Null value for each row, otherwise insert 99.9
-df$with_column(
+df$with_columns(
   pl$min("a", "b", "c", 99.9)$alias("d")
 )
 
diff --git a/man/pl_pl.Rd b/man/pl_pl.Rd
index 51c8a7b0b..7672f1663 100644
--- a/man/pl_pl.Rd
+++ b/man/pl_pl.Rd
@@ -6,7 +6,7 @@
 \alias{pl}
 \title{The complete polars public API.}
 \format{
-An object of class \code{pl_polars_env} (inherits from \code{environment}) of length 77.
+An object of class \code{pl_polars_env} (inherits from \code{environment}) of length 78.
 }
 \usage{
 pl
diff --git a/man/pl_sum.Rd b/man/pl_sum.Rd
index 631e23ea0..41e2249ff 100644
--- a/man/pl_sum.Rd
+++ b/man/pl_sum.Rd
@@ -35,11 +35,11 @@ pl$DataFrame()$select(pl$sum(1:5))
 df = pl$DataFrame(a = 1:2, b = 3:4, c = 5:6)
 
 # column as list
-df$with_column(pl$sum(list("a", "c")))
-df$with_column(pl$sum(list("a", "c", 42L)))
+df$with_columns(pl$sum(list("a", "c")))
+df$with_columns(pl$sum(list("a", "c", 42L)))
 
 # two eqivalent lines
-df$with_column(pl$sum(list(pl$col("a") + pl$col("b"), "c")))
-df$with_column(pl$sum(list("*")))
+df$with_columns(pl$sum(list(pl$col("a") + pl$col("b"), "c")))
+df$with_columns(pl$sum(list("*")))
 }
 \keyword{Expr_new}
diff --git a/src/rust/src/lazy/dataframe.rs b/src/rust/src/lazy/dataframe.rs
index ea875b77e..b17dd3d6f 100644
--- a/src/rust/src/lazy/dataframe.rs
+++ b/src/rust/src/lazy/dataframe.rs
@@ -231,6 +231,8 @@ impl LazyFrame {
     }
 
     fn with_column(&self, expr: &Expr) -> LazyFrame {
+        R!("warning('`with_column()` is deprecated and will be removed in polars 0.9.0. Please use `with_columns()` instead.')")
+        .expect("warning will not fail");
         LazyFrame(self.0.clone().with_column(expr.0.clone()))
     }
 
diff --git a/src/rust/src/rlib.rs b/src/rust/src/rlib.rs
index 5a38dd2f1..f999de008 100644
--- a/src/rust/src/rlib.rs
+++ b/src/rust/src/rlib.rs
@@ -59,33 +59,40 @@ pub fn hor_concat_df(dfs: &VecDataFrame) -> List {
 #[extendr]
 fn min_exprs(exprs: &ProtoExprArray) -> Expr {
     let exprs = exprs.to_vec("select");
-    polars::lazy::dsl::min_exprs(exprs).into()
+    pl::min_exprs(exprs).into()
 }
 
 #[extendr]
 fn max_exprs(exprs: &ProtoExprArray) -> Expr {
     let exprs = exprs.to_vec("select");
-    polars::lazy::dsl::max_exprs(exprs).into()
+    pl::max_exprs(exprs).into()
 }
 
 #[extendr]
 fn coalesce_exprs(exprs: &ProtoExprArray) -> Expr {
     let exprs: Vec<pl::Expr> = exprs.to_vec("select");
-    polars::lazy::dsl::coalesce(exprs.as_slice()).into()
+    pl::coalesce(exprs.as_slice()).into()
 }
 
 #[extendr]
 fn sum_exprs(exprs: &ProtoExprArray) -> Expr {
     let exprs = exprs.to_vec("select");
-    polars::lazy::dsl::sum_exprs(exprs).into()
+    pl::sum_exprs(exprs).into()
 }
 
 #[extendr]
 fn concat_list(exprs: &ProtoExprArray) -> Result<Expr, String> {
     let exprs = exprs.to_vec("select");
-    Ok(Expr(
-        polars::lazy::dsl::concat_list(exprs).map_err(|err| err.to_string())?,
-    ))
+    Ok(Expr(pl::concat_list(exprs).map_err(|err| err.to_string())?))
+}
+
+#[extendr]
+fn concat_str(dotdotdot: Robj, separator: Robj) -> RResult<Expr> {
+    Ok(pl::concat_str(
+        robj_to!(Vec, PLExprCol, dotdotdot)?,
+        robj_to!(str, separator)?,
+    )
+    .into())
 }
 
 #[extendr]
@@ -149,10 +156,7 @@ fn r_date_range_lazy(
 //for now just use inner directly
 #[extendr]
 fn as_struct(exprs: Robj) -> Result<Expr, String> {
-    Ok(polars::lazy::dsl::as_struct(
-        crate::utils::list_expr_to_vec_pl_expr(exprs, true)?.as_slice(),
-    )
-    .into())
+    Ok(pl::as_struct(crate::utils::list_expr_to_vec_pl_expr(exprs, true)?.as_slice()).into())
 }
 
 #[extendr]
@@ -277,6 +281,7 @@ extendr_module! {
     fn sum_exprs;
 
     fn concat_list;
+    fn concat_str;
     fn r_date_range;
     fn r_date_range_lazy;
     fn as_struct;
diff --git a/src/rust/src/rpolarserr.rs b/src/rust/src/rpolarserr.rs
index 9cb87673f..a912f148f 100644
--- a/src/rust/src/rpolarserr.rs
+++ b/src/rust/src/rpolarserr.rs
@@ -8,7 +8,7 @@ use thiserror::Error;
 
 #[derive(Clone, Debug, Error)]
 pub enum Rctx {
-    #[error("The argument [{0}] cause an error")]
+    #[error("The argument [{0}] caused an error")]
     BadArg(String),
     #[error("Got value [{0}]")]
     BadVal(String),
diff --git a/src/rust/src/utils/mod.rs b/src/rust/src/utils/mod.rs
index 47b4558ad..4546602ac 100644
--- a/src/rust/src/utils/mod.rs
+++ b/src/rust/src/utils/mod.rs
@@ -793,7 +793,11 @@ macro_rules! robj_to {
             if ($a.is_null()) {
                 Ok(None)
             } else {
-                Some($crate::robj_to_inner!($type, $a).bad_arg(stringify!($a))).transpose()
+                Some(
+                    $crate::robj_to_inner!($type, $a)
+                        .bad_arg(stringify!($a).replace("dotdotdot", " `...` ")),
+                )
+                .transpose()
             }
         })
     }};
@@ -807,7 +811,7 @@ macro_rules! robj_to {
             let x = if !x.is_list() && x.len() != 1 {
                 extendr_api::call!("as.list", x)
                     .mistyped(std::any::type_name::<List>())
-                    .bad_arg(stringify!($a))?
+                    .bad_arg(stringify!($a).replace("dotdotdot", " `...` "))?
             } else {
                 x
             };
@@ -835,19 +839,19 @@ macro_rules! robj_to {
         use $crate::rpolarserr::WithRctx;
         $crate::robj_to_inner!($type, $a)
             .and_then($f)
-            .bad_arg(stringify!($a))
+            .bad_arg(stringify!($a).replace("dotdotdot", " `...` "))
     }};
 
     ($type:ident, $a:ident) => {{
         use $crate::rpolarserr::WithRctx;
-        $crate::robj_to_inner!($type, $a).bad_arg(stringify!($a))
+        $crate::robj_to_inner!($type, $a).bad_arg(stringify!($a).replace("dotdotdot", " `...` "))
     }};
 
     ($type:ident, $a:ident, $b:expr) => {{
         use $crate::rpolarserr::WithRctx;
         $crate::robj_to_inner!($type, $a)
             .hint($b)
-            .bad_arg(stringify!($a))
+            .bad_arg(stringify!($a).replace("dotdotdot", " `...` "))
     }};
 }
 
diff --git a/tests/testthat/test-expr.R b/tests/testthat/test-expr.R
index eaac6d8cb..2d0496767 100644
--- a/tests/testthat/test-expr.R
+++ b/tests/testthat/test-expr.R
@@ -2344,3 +2344,33 @@ test_that("implode", {
   expect_identical(pl$lit(1:4)$implode()$to_r(), pl$lit(list(1:4))$to_r())
   expect_grepl_error(pl$lit(42)$implode(42), c("unused argument"))
 })
+
+test_that("concat_str", {
+  df = pl$DataFrame(
+    a = c(1, 2, 3),
+    b = c("dogs", "cats", NA),
+    c = c("play", "swim", "walk")
+  )
+
+  out = df$with_columns(
+    pl$concat_str(
+      pl$col("a") * 2,
+      "b",
+      pl$col("c"),
+      separator = " "
+    )$alias("full_sentence")
+  )$to_data_frame()
+
+  expect_equal(dim(out), c(3, 4))
+  expect_equal(
+    out$full_sentence,
+    c("2.0 dogs play", "4.0 cats swim", NA)
+  )
+
+  # check error for something which cannot be turned into an Expression
+  ctxs = pl$concat_str("a", complex(1)) |>
+    (\(x) result(x)$err$contexts())()
+  expect_identical(ctxs$BadArgument, " `...` ")
+  expect_identical(ctxs$Hint, "element no. [2] ")
+  expect_identical(ctxs$PlainErrorMessage, "cannot be converted into an Expr")
+})
diff --git a/tests/testthat/test-extendr-meta.R b/tests/testthat/test-extendr-meta.R
index 92922542a..9a9708967 100644
--- a/tests/testthat/test-extendr-meta.R
+++ b/tests/testthat/test-extendr-meta.R
@@ -1,18 +1,16 @@
 test_that("clone_robj + mem_adress", {
-
   # clone mutable
-  env  = new.env(parent = emptyenv())
+  env = new.env(parent = emptyenv())
   env2 = clone_robj(env)
   env$foo = 42
-  expect_identical(env,env2)
+  expect_identical(env, env2)
   expect_identical(pl$mem_address(env), pl$mem_address(env2))
 
   # clone immutable, not the same
   l = list()
   l2 = clone_robj(l)
   l$foo = 42
-  expect_identical(l,list(foo = 42))
-  expect_identical(l2,list())
+  expect_identical(l, list(foo = 42))
+  expect_identical(l2, list())
   expect_false(pl$mem_address(l) == pl$mem_address(l2))
-
 })