#!/usr/bin/env rc
#
# Extract code blocks from Literate Haskell files and print them on
# standard output.
#
# Blank lines will be used to separate logical code blocks (sequences
# of lines starting with `>`, or `\begin{code}`/`\end{code}` pairs),
# but the contents of the blocks are printed verbatim.
#
# Usage: `lhscode [file ...]`, reading from standard input if no files
# are provided.

flag e +

cat $* | awk '
BEGIN {incode=0; inbird=0; was=0}
/^\\begin{code}[ ]*$/ { if (was==1) print ""; was=1; incode=1; next; }
/^\\end{code}[ ]*$/   { incode=0;}
/^> (.*)$/            {
    if (incode==0) {
       if (was==1) { print ""; was=0; }
       inbird=1; print substr($0, 3, length($0)-2); next;
    }
}
{ if (incode==1) { print $0; }
  else if (inbird==1) { print ""; inbird=0; }  }'