Function: read
Section: programming/specific
C-Name: gp_read_file
Prototype: D"",s,
Help: read({filename}): read from the input file filename. If filename is
 omitted, reread last input file, be it from read() or \r.
Description:
 (str):gen      gp_read_file($1)
Doc: reads in the file
 \var{filename} (subject to string expansion). If \var{filename} is
 omitted, re-reads the last file that was fed into \kbd{gp}. The return
 value is the result of the last expression evaluated.

 If a GP \tet{binary file} is read using this command (see
 \secref{se:writebin}), the file is loaded and the last object in the file
 is returned.

 In case the file you read in contains an \tet{allocatemem} statement (to be
 generally avoided), you should leave \kbd{read} instructions by themselves,
 and not part of larger instruction sequences.

 \misctitle{Variants} \kbd{readvec} allows to read a whole file at once;
 \kbd{fileopen} followed by either \kbd{fileread} (evaluated lines) or
 \kbd{filereadstr} (lines as non-evaluated strings) allows to read a file
 one line at a time.
