perl/step7_quote.pl

   1 use strict;
   2 use warnings FATAL => qw(all);
   3 no if $] >= 5.018, warnings => "experimental::smartmatch";
   4 use File::Basename;
   5 use lib dirname (__FILE__);
   6 use readline qw(mal_readline set_rl_mode);
   7 use feature qw(switch);
   8 use Data::Dumper;
   9
  10 use types qw($nil $true $false _sequential_Q _symbol_Q _list_Q);
  11 use reader;
  12 use printer;
  13 use env;
  14 use core qw($core_ns);
  15
  16 # read
  17 sub READ {
  18     my $str = shift;
  19     return reader::read_str($str);
  20 }
  21
  22 # eval
  23 sub is_pair {
  24     my ($x) = @_;
  25     return _sequential_Q($x) && scalar(@{$x->{val}}) > 0;
  26 }
  27
  28 sub quasiquote {
  29     my ($ast) = @_;
  30     if (!is_pair($ast)) {
  31         return List->new([Symbol->new("quote"), $ast]);
  32     } elsif (_symbol_Q($ast->nth(0)) && ${$ast->nth(0)} eq 'unquote') {
  33         return $ast->nth(1);
  34     } elsif (is_pair($ast->nth(0)) && _symbol_Q($ast->nth(0)->nth(0)) &&
  35              ${$ast->nth(0)->nth(0)} eq 'splice-unquote') {
  36         return List->new([Symbol->new("concat"),
  37                           $ast->nth(0)->nth(1),
  38                           quasiquote($ast->rest())]);
  39     } else {
  40         return List->new([Symbol->new("cons"),
  41                           quasiquote($ast->nth(0)),
  42                           quasiquote($ast->rest())]);
  43     }
  44 }
  45
  46 sub eval_ast {
  47     my($ast, $env) = @_;
  48     given (ref $ast) {
  49         when (/^Symbol/) {
  50             $env->get($ast);
  51         }
  52         when (/^List/) {
  53             my @lst = map {EVAL($_, $env)} @{$ast->{val}};
  54             return List->new(\@lst);
  55         }
  56         when (/^Vector/) {
  57             my @lst = map {EVAL($_, $env)} @{$ast->{val}};
  58             return Vector->new(\@lst);
  59         }
  60         when (/^HashMap/) {
  61             my $new_hm = {};
  62             foreach my $k (keys( %{ $ast->{val} })) {
  63                 $new_hm->{$k} = EVAL($ast->get($k), $env);
  64             }
  65             return HashMap->new($new_hm);
  66         }
  67         default {
  68             return $ast;
  69         }
  70     }
  71 }
  72
  73 sub EVAL {
  74     my($ast, $env) = @_;
  75
  76     while (1) {
  77
  78     #print "EVAL: " . printer::_pr_str($ast) . "\n";
  79     if (! _list_Q($ast)) {
  80         return eval_ast($ast, $env);
  81     }
  82
  83     # apply list
  84     my ($a0, $a1, $a2, $a3) = @{$ast->{val}};
  85     given ((ref $a0) =~ /^Symbol/ ? $$a0 : $a0) {
  86         when (/^def!$/) {
  87             my $res = EVAL($a2, $env);
  88             return $env->set($a1, $res);
  89         }
  90         when (/^let\*$/) {
  91             my $let_env = Env->new($env);
  92             for(my $i=0; $i < scalar(@{$a1->{val}}); $i+=2) {
  93                 $let_env->set($a1->nth($i), EVAL($a1->nth($i+1), $let_env));
  94             }
  95             $ast = $a2;
  96             $env = $let_env;
  97             # Continue loop (TCO)
  98         }
  99         when (/^quote$/) {
 100             return $a1;
 101         }
 102         when (/^quasiquote$/) {
 103             $ast = quasiquote($a1);
 104             # Continue loop (TCO)
 105         }
 106         when (/^do$/) {
 107             eval_ast($ast->slice(1, $#{$ast->{val}}-1), $env);
 108             $ast = $ast->nth($#{$ast->{val}});
 109             # Continue loop (TCO)
 110         }
 111         when (/^if$/) {
 112             my $cond = EVAL($a1, $env);
 113             if ($cond eq $nil || $cond eq $false) {
 114                 $ast = $a3 ? $a3 : $nil;
 115             } else {
 116                 $ast = $a2;
 117             }
 118             # Continue loop (TCO)
 119         }
 120         when (/^fn\*$/) {
 121             return Function->new(\&EVAL, $a2, $env, $a1);
 122         }
 123         default {
 124             my $el = eval_ast($ast, $env);
 125             my $f = $el->nth(0);
 126             if ((ref $f) =~ /^Function/) {
 127                 $ast = $f->{ast};
 128                 $env = $f->gen_env($el->rest());
 129                 # Continue loop (TCO)
 130             } else {
 131                 return &{ $f }($el->rest());
 132             }
 133         }
 134     }
 135
 136     } # TCO while loop
 137 }
 138
 139 # print
 140 sub PRINT {
 141     my $exp = shift;
 142     return printer::_pr_str($exp);
 143 }
 144
 145 # repl
 146 my $repl_env = Env->new();
 147 sub REP {
 148     my $str = shift;
 149     return PRINT(EVAL(READ($str), $repl_env));
 150 }
 151
 152 # core.pl: defined using perl
 153 foreach my $n (%$core_ns) {
 154     $repl_env->set(Symbol->new($n), $core_ns->{$n});
 155 }
 156 $repl_env->set(Symbol->new('eval'), sub { EVAL($_[0]->nth(0), $repl_env); });
 157 my @_argv = map {String->new($_)}  @ARGV[1..$#ARGV];
 158 $repl_env->set(Symbol->new('*ARGV*'), List->new(\@_argv));
 159
 160 # core.mal: defined using the language itself
 161 REP("(def! not (fn* (a) (if a false true)))");
 162 REP("(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \")\")))))");
 163
 164 if (scalar(@ARGV) > 0 && $ARGV[0] eq "--raw") {
 165     set_rl_mode("raw");
 166     shift @ARGV;
 167 }
 168 if (scalar(@ARGV) > 0) {
 169     REP("(load-file \"" . $ARGV[0] . "\")");
 170     exit 0;
 171 }
 172 while (1) {
 173     my $line = mal_readline("user> ");
 174     if (! defined $line) { last; }
 175     do {
 176         local $@;
 177         my $ret;
 178         eval {
 179             use autodie; # always "throw" errors
 180             print(REP($line), "\n");
 181             1;
 182         } or do {
 183             my $err = $@;
 184             given (ref $err) {
 185                 when (/^BlankException/) {
 186                     # ignore and continue
 187                 }
 188                 default {
 189                     chomp $err;
 190                     print "Error: $err\n";
 191                 }
 192             }
 193         };
 194     };
 195 }