Perl: add step7_quote

3 files changed, 195 insertions, 7 deletions

diff --git a/perl/core.pm b/perl/core.pm
index a529d21..a243dcb 100644
--- a/perl/core.pm
+++ b/perl/core.pm
@@ -38,6 +38,23 @@ sub slurp {
 }
 
 
+# List functions
+
+sub cons {
+    my ($a, $b) = @_;
+    my @new_arr = @{[$a]};
+    push @new_arr, @$b;
+    List->new(\@new_arr);
+}
+
+sub concat {
+    my ($a, $b) = @_;
+    my @new_arr = @{$a};
+    push @new_arr, @$b;
+    List->new(\@new_arr);
+}
+
+
 our $core_ns = {
     '=' =>  sub { _equal_Q($_[0][0], $_[0][1]) ? $true : $false },
 
@@ -58,6 +75,9 @@ our $core_ns = {
 
     'list'  => sub { $_[0] },
     'list?' => sub { _list_Q($_[0][0]) ? $true : $false },
+
+    'cons' => sub { cons($_[0][0], $_[0][1]) },
+    'concat' => sub { concat($_[0][0], $_[0][1]) },
     'empty?' => sub { scalar(@{$_[0][0]}) == 0 ? $true : $false },
     'count' => sub { Integer->new(scalar(@{$_[0][0]})) },
 };
diff --git a/perl/reader.pm b/perl/reader.pm
index 6fac066..e173910 100644
--- a/perl/reader.pm
+++ b/perl/reader.pm
@@ -78,13 +78,21 @@ sub read_form {
     my($rdr) = @_;
     my $token = $rdr->peek();
     given ($token) {
-        when(')') { die "unexpected ')'"; }
-        when('(') { return read_list($rdr, 'List'); }
-        when(']') { die "unexpected ']'"; }
-        when('[') { return read_list($rdr, 'Vector', '[', ']'); }
-        when('}') { die "unexpected '}'"; }
-        when('{') { return read_list($rdr, 'HashMap', '{', '}'); }
-        default  { return read_atom($rdr); }
+        when("'") { $rdr->next(); List->new([Symbol->new('quote'),
+                                             read_form($rdr)]) }
+        when('`') { $rdr->next(); List->new([Symbol->new('quasiquote'),
+                                             read_form($rdr)]) }
+        when('~') { $rdr->next(); List->new([Symbol->new('unquote'),
+                                             read_form($rdr)]) }
+        when('~@') { $rdr->next(); List->new([Symbol->new('splice-unquote'),
+                                              read_form($rdr)]) }
+        when(')') { die "unexpected ')'" }
+        when('(') { return read_list($rdr, 'List') }
+        when(']') { die "unexpected ']'" }
+        when('[') { return read_list($rdr, 'Vector', '[', ']') }
+        when('}') { die "unexpected '}'" }
+        when('{') { return read_list($rdr, 'HashMap', '{', '}') }
+        default  { return read_atom($rdr) }
     }
 }
 
diff --git a/perl/step7_quote.pl b/perl/step7_quote.pl
new file mode 100644
index 0000000..7b9f92f
--- /dev/null
+++ b/perl/step7_quote.pl
@@ -0,0 +1,160 @@
+use strict;
+use warnings FATAL => qw(all);
+use readline qw(readline);
+use feature qw(switch);
+use Data::Dumper;
+
+use types qw($nil $true $false _sequential_Q);
+use reader;
+use printer;
+use env;
+use core qw($core_ns);
+
+# read
+sub READ {
+    my $str = shift;
+    return reader::read_str($str);
+}
+
+# eval
+sub is_pair {
+    my ($x) = @_;
+    return _sequential_Q($x) && scalar(@$x) > 0;
+}
+
+sub quasiquote {
+    my ($ast) = @_;
+    if (!is_pair($ast)) {
+        return List->new([Symbol->new("quote"), $ast]);
+    } elsif (((ref $ast->[0]) =~ /^Symbol/) &&
+             ${$ast->[0]} eq 'unquote') {
+        return $ast->[1];
+    } elsif (is_pair($ast->[0]) &&
+             ((ref $ast->[0][0]) =~ /^Symbol/) &&
+             ${$ast->[0][0]} eq 'splice-unquote') {
+        return List->new([Symbol->new("concat"),
+                          $ast->[0][1],
+                          quasiquote($ast->rest())]);
+    } else {
+        return List->new([Symbol->new("cons"),
+                          quasiquote($ast->[0]),
+                          quasiquote($ast->rest())]);
+    }
+}
+
+sub eval_ast {
+    my($ast, $env) = @_;
+    given (ref $ast) {
+        when (/^Symbol/) {
+            $env->get($$ast);
+        }
+        when (/^List/) {
+            my @lst = map {EVAL($_, $env)} @$ast;
+            return List->new(\@lst);
+        }
+        default {
+            return $ast;
+        }
+    }
+}
+
+sub EVAL {
+    my($ast, $env) = @_;
+
+    while (1) {
+
+    #print "EVAL: " . printer::_pr_str($ast) . "\n";
+    if (! ((ref $ast) =~ /^List/)) {
+        return eval_ast($ast, $env);
+    }
+
+    # apply list
+    my ($a0, $a1, $a2, $a3) = @$ast;
+    given ((ref $a0) =~ /^Symbol/ ? $$a0 : $a0) {
+        when (/^def!$/) {
+            my $res = EVAL($a2, $env);
+            return $env->set($$a1, $res);
+        }
+        when (/^let\*$/) {
+            my $let_env = Env->new($env);
+            for(my $i=0; $i < scalar(@{$a1}); $i+=2) {
+                $let_env->set(${$a1->[$i]}, EVAL($a1->[$i+1], $let_env));
+            }
+            return EVAL($a2, $let_env);
+        }
+        when (/^quote$/) {
+            return $a1;
+        }
+        when (/^quasiquote$/) {
+            return EVAL(quasiquote($a1), $env);
+        }
+        when (/^do$/) {
+            eval_ast($ast->slice(1, $#{$ast}-1), $env);
+            $ast = $ast->[$#{$ast}];
+        }
+        when (/^if$/) {
+            my $cond = EVAL($a1, $env);
+            if ($cond eq $nil || $cond eq $false) {
+                $ast = $a3 ? $a3 : $nil;
+            } else {
+                $ast = $a2;
+            }
+        }
+        when (/^fn\*$/) {
+            return Function->new(\&EVAL, $a2, $env, $a1);
+        }
+        default {
+            my $el = eval_ast($ast, $env);
+            my $f = $el->[0];
+            if ((ref $f) =~ /^Function/) {
+                $ast = $f->{ast};
+                $env = $f->gen_env($el->rest());
+            } else {
+                return &{ $f }($el->rest());
+            }
+        }
+    }
+
+    } # TCO while loop
+}
+
+# print
+sub PRINT {
+    my $exp = shift;
+    return printer::_pr_str($exp);
+}
+
+# repl
+my $repl_env = Env->new();
+sub REP {
+    my $str = shift;
+    return PRINT(EVAL(READ($str), $repl_env));
+}
+
+# core.pl: defined using perl
+foreach my $n (%$core_ns) { $repl_env->set($n, $core_ns->{$n}); }
+$repl_env->set('eval', sub { EVAL($_[0][0], $repl_env); });
+my @_argv = map {String->new($_)}  @ARGV[1..$#ARGV];
+$repl_env->set('*ARGV*', List->new(\@_argv));
+
+# core.mal: defined using the language itself
+REP("(def! not (fn* (a) (if a false true)))");
+REP("(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \")\")))))");
+
+if ($#ARGV > 0) {
+    REP("(load-file \"" . $ARGV[0] . "\")");
+    exit 0;
+}
+while (1) {
+    my $line = readline("user> ");
+    if (! defined $line) { last; }
+    eval {
+        use autodie; # always "throw" errors
+        print(REP($line), "\n");
+        1;
+    }; 
+    if (my $err = $@) {
+        chomp $err;
+        print "Error: $err\n";
+    }
+}