Environment (see also pce<-environment)
for the child process. Either the get- or the send-method will create a
sheet mapping environment variable named onto values and fill the slot
with this sheet. Send changes the sheet's content.
If this variable is set on process->open,
the child will be passed these environment variables. For example, to
start tex myfile.tex with TEXINPUTS set to’../TeXmacros:/usr/local/lib/tex/macros’:
?- new(P, process(tex, 'myfile.tex')),
send(P, environment, 'TEXINPUTS',
'../TeXmacros:/usr/local/lib/tex/macros'),
send(P, input_message,
message(@pce, write, @arg1)),
send(P, open).
