Perl: add readline interface and step0_repl

2 files changed, 68 insertions, 0 deletions

diff --git a/perl/readline.pm b/perl/readline.pm
new file mode 100644
index 0000000..d2e2098
--- /dev/null
+++ b/perl/readline.pm
@@ -0,0 +1,35 @@
+# To get readline line editing functionality, please install
+# Term::ReadLine::Gnu (GPL) or Term::ReadLine::Perl (GPL, Artistic)
+# from CPAN.
+
+package readline;
+use strict;
+use warnings;
+use Exporter 'import';
+our @EXPORT_OK = qw( readline );
+
+use Term::ReadLine;
+
+my $_rl = Term::ReadLine->new('Mal');
+$_rl->ornaments(0);
+#print "Using ReadLine implementation: " . $_rl->ReadLine() . "\n";
+my $OUT = $_rl->OUT || \*STDOUT;
+my $_history_loaded = 0;
+
+sub readline {
+    my($prompt) = @_;
+    my $line = undef;
+    if (! $_history_loaded) {
+        $_history_loaded = 1;
+        # TODO: load history
+    }
+
+    if (defined ($line = $_rl->readline($prompt))) {
+        $_rl->addhistory($line) if $line =~ /\S/;
+        # TODO: save history
+        return $line;
+    } else {
+        return undef;
+    }
+}
+1;
diff --git a/perl/step0_repl.pl b/perl/step0_repl.pl
new file mode 100644
index 0000000..8295cc0
--- /dev/null
+++ b/perl/step0_repl.pl
@@ -0,0 +1,33 @@
+use strict;
+use warnings;
+use readline qw(readline);
+
+# read
+sub READ {
+    my $str = shift;
+    return $str;
+}
+
+# eval
+sub EVAL {
+    my($ast, $env) = @_;
+    return $ast;
+}
+
+# print
+sub PRINT {
+    my $exp = shift;
+    return $exp;
+}
+
+# repl
+sub REP {
+    my $str = shift;
+    return PRINT(EVAL(READ($str), {}));
+}
+
+while (1) {
+    my $line = readline("user> ");
+    if (! defined $line) { last; }
+    print(REP($line), "\n");
+}