An initial implementation of $*ARGFILES and lines().

src/core/IO.pm

@@ -70,10 +70,15 @@ class IO {
         }
     }
 
+    method opened() {
+        nqp::p6bool(nqp::istrue($!PIO));
+    }
+
     method print(*@list) {
         $!PIO.print(nqp::unbox_s(@list.shift.Str)) while @list.gimme(1);
         Bool::True
     }
+
     method say(|$) {
         my Mu $args := pir::perl6_current_args_rpa__P();
         nqp::shift($args);
@@ -94,6 +99,11 @@ multi sub open($filename, :$r, :$w, :$a, :$bin, :$chomp = Bool::True) {
     IO.new.open($filename, :$r, :$w, :$a, :$bin, :$chomp);
 }
 
+proto sub lines(|$) { * }
+multi sub lines($fh = $*ARGFILES, $limit = $Inf) { 
+    $fh.lines($limit) 
+}
+
 $PROCESS::IN  = open('-');
 $PROCESS::OUT = open('-', :w);
 $PROCESS::ERR = IO.new;

src/core/IO/ArgFiles.pm

@@ -0,0 +1,36 @@
+my class ArgFiles {
+    has $.args;
+    has $.filename;
+    has $!io;
+    has $!ins;
+
+    method eof() { ! $!args }
+
+    method get() {
+        unless $!io.defined && $!io.opened {
+            $!filename = $!args ?? $!args.shift !! '-';
+            $!io = open($!filename, :r) ||
+                fail "Unable to open file '$!filename'";
+        }
+        my $x = $!io.get;
+        while !$x.defined {
+            $!io.close;
+            $!io = IO;
+            fail "End of argfiles reached" unless $!args;
+            $x = self.get;
+        }
+        $!ins++;
+        $x;
+    }
+
+    method lines($limit = *) {
+        my $l = $limit ~~ Whatever ?? $Inf !! $limit;
+        gather while !$.eof && $l-- > 0 {
+           my $line = $.get;
+           if $line.defined {
+               take $line;
+           }
+        }
+    }
+}
+

src/core/terms.pm

@@ -7,5 +7,6 @@ sub term:<time>() { nqp::p6box_i(pir::time__I()) }
     nqp::shift($argiter) if $argiter;
     @ARGS.push(nqp::p6box_s(nqp::shift($argiter))) while $argiter;
     nqp::bindkey(pir::get_who__PP(PROCESS), '@ARGS', @ARGS);
+    $PROCESS::ARGFILES = ArgFiles.new(:args(@ARGS));
 }
 

tools/build/Makefile.in

@@ -173,6 +173,7 @@ CORE_SOURCES = \
   src/core/Sub.pm \
   src/core/Method.pm \
   src/core/IO.pm \
+  src/core/IO/ArgFiles.pm \
   src/core/Rat.pm \
   src/core/Complex.pm \
   src/core/Exception.pm \