From 9e5b215158a40ad983cbc22464761524845dd9bf Mon Sep 17 00:00:00 2001
From: Joel Martin <github@martintribe.org>
Date: Sat, 19 Apr 2014 13:55:30 -0500
Subject: Perl: add readline interface and step0_repl

---
 README.md          | 11 +++++++++++
 docs/TODO          |  1 -
 perl/readline.pm   | 35 +++++++++++++++++++++++++++++++++++
 perl/step0_repl.pl | 33 +++++++++++++++++++++++++++++++++
 4 files changed, 79 insertions(+), 1 deletion(-)
 create mode 100644 perl/readline.pm
 create mode 100644 perl/step0_repl.pl

diff --git a/README.md b/README.md
index 2aa96ae..2688f21 100644
--- a/README.md
+++ b/README.md
@@ -121,6 +121,17 @@ cd make
 make -f stepX_YYY.mk
 ```
 
+### Perl 5
+
+For readline line editing support, install Term::ReadLine::Perl or
+Term::ReadLine::Gnu from CPAN.
+
+```
+cd perl
+perl stepX_YYY.pl
+```
+
+
 ### PHP 5.3
 
 ```
diff --git a/docs/TODO b/docs/TODO
index adde9a8..e5926e0 100644
--- a/docs/TODO
+++ b/docs/TODO
@@ -29,7 +29,6 @@ Clojure:
 
 Java:
     - step9_interop
-    - store ILambda in function (like c#)?
 
 Javascript:
 
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");
+}
-- 
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