Generate tabularray and compute sub-result for each row using functional library

Question

I must use longtblr from tabularray package and would like to calculate simple products on each row.

Trouble is, the product displayed in the final result is the same for every row : the product from the ending row. As illustrated below, the first row should end with 4.4 and not 8.

\documentclass{article}
\usepackage{tabularray}
\UseTblrLibrary{functional}
\IgnoreSpacesOn
\FpNew \Total
\PrgNewFunction \Product {mmm} {
  \FpSet \SubTotal {#2 * #3}
  \TlSet \Row {#1 & #2 & #3 & {\FpUse \SubTotal}\\}
  \FpAdd \Total {\FpUse \SubTotal}
  \Return {\TlUse \Row}
}
\IgnoreSpacesOff
\begin{document}
\begin{longtblr}[evaluate=\Product]{cccc}
  \Product{Text}{1.1}{4}
  \Product{Text}{4}{2}
  Total &&& \FpUse \Total
\end{longtblr}
\end{document}

I'm using latest tabularray and functional packages from github for these functionalities.

I'm also computing the total sum from the last column and it is working fine.

Thanks in advance for any helpful answer ! And many thanks to @L.J.R. for creating this wonderful TeX package (the most feature-packed tabular environment to my knowledge) !

Answer 1

To avoid potential naming conflicts with commands in LaTeX kernel and other packages, functional package has changed its naming scheme for functions from \UpperCamelCase to \lowerCamelCase since version 2022G (2022-05-22).

Also there is some renaming for single-word functions (see the changelog). For example, \Return has been renamed as \prgReturn.

For backward compatibility, those old UpperCamelCase function names can still be used for some time as long as they are not used by kernel or other packages, but they will be removed in the future.

---

An inner function is evaluated only when it occurs at the beginning of an argument. So the following line

\tlSet \Row {#1 & #2 & #3 & {\fpUse \SubTotal}\\}

need to be changed to

\tlSet \Row {#1 & #2 & #3 & }
\tlPutRight \Row {\fpUse \SubTotal}
\tlPutRight \Row {\\}

Now you get the expected result:

\documentclass{article}
\usepackage{tabularray}
\UseTblrLibrary{functional}
\IgnoreSpacesOn
\fpNew \Total
\prgNewFunction \Product {mmm} {
  \fpSet \SubTotal {#2 * #3}
  \tlSet \Row {#1 & #2 & #3 & }
  \tlPutRight \Row {\fpUse \SubTotal}
  \tlPutRight \Row {\\}
  \fpAdd \Total {\fpUse \SubTotal}
  \prgReturn {\tlUse \Row}
}
\IgnoreSpacesOff
\begin{document}
\begin{longtblr}[evaluate=\Product]{cccc}
  \Product{Text}{1.1}{4}
  \Product{Text}{4}{2}
  Total &&& \fpUse \Total
\end{longtblr}
\end{document}