perl/step8_macros.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 is_macro_call {
  47     my ($ast, $env) = @_;
  48     if (_list_Q($ast) &&
  49         _symbol_Q($ast->nth(0)) &&
  50         $env->find($ast->nth(0))) {
  51         my ($f) = $env->get($ast->nth(0));
  52         if ((ref $f) =~ /^Function/) {
  53             return $f->{ismacro};
  54         }
  55     }
  56     return 0;
  57 }
  58
  59 sub macroexpand {
  60     my ($ast, $env) = @_;
  61     while (is_macro_call($ast, $env)) {
  62         my $mac = $env->get($ast->nth(0));
  63         $ast = $mac->apply($ast->rest());
  64     }
  65     return $ast;
  66 }
  67
  68
  69 sub eval_ast {
  70     my($ast, $env) = @_;
  71     given (ref $ast) {
  72         when (/^Symbol/) {
  73             $env->get($ast);
  74         }
  75         when (/^List/) {
  76             my @lst = map {EVAL($_, $env)} @{$ast->{val}};
  77             return List->new(\@lst);
  78         }
  79         when (/^Vector/) {
  80             my @lst = map {EVAL($_, $env)} @{$ast->{val}};
  81             return Vector->new(\@lst);
  82         }
  83         when (/^HashMap/) {
  84             my $new_hm = {};
  85             foreach my $k (keys( %{ $ast->{val} })) {
  86                 $new_hm->{$k} = EVAL($ast->get($k), $env);
  87             }
  88             return HashMap->new($new_hm);
  89         }
  90         default {
  91             return $ast;
  92         }
  93     }
  94 }
  95
  96 sub EVAL {
  97     my($ast, $env) = @_;
  98
  99     while (1) {
 100
 101     #print "EVAL: " . printer::_pr_str($ast) . "\n";
 102     if (! _list_Q($ast)) {
 103         return eval_ast($ast, $env);
 104     }
 105
 106     # apply list
 107     $ast = macroexpand($ast, $env);
 108     if (! _list_Q($ast)) { return $ast; }
 109
 110     my ($a0, $a1, $a2, $a3) = @{$ast->{val}};
 111     given ((ref $a0) =~ /^Symbol/ ? $$a0 : $a0) {
 112         when (/^def!$/) {
 113             my $res = EVAL($a2, $env);
 114             return $env->set($a1, $res);
 115         }
 116         when (/^let\*$/) {
 117             my $let_env = Env->new($env);
 118             for(my $i=0; $i < scalar(@{$a1->{val}}); $i+=2) {
 119                 $let_env->set($a1->nth($i), EVAL($a1->nth($i+1), $let_env));
 120             }
 121             $ast = $a2;
 122             $env = $let_env;
 123             # Continue loop (TCO)
 124         }
 125         when (/^quote$/) {
 126             return $a1;
 127         }
 128         when (/^quasiquote$/) {
 129             $ast = quasiquote($a1);
 130             # Continue loop (TCO)
 131         }
 132         when (/^defmacro!$/) {
 133             my $func = EVAL($a2, $env);
 134             $func->{ismacro} = 1;
 135             return $env->set($a1, $func);
 136         }
 137         when (/^macroexpand$/) {
 138             return macroexpand($a1, $env);
 139         }
 140         when (/^do$/) {
 141             eval_ast($ast->slice(1, $#{$ast->{val}}-1), $env);
 142             $ast = $ast->nth($#{$ast->{val}});
 143             # Continue loop (TCO)
 144         }
 145         when (/^if$/) {
 146             my $cond = EVAL($a1, $env);
 147             if ($cond eq $nil || $cond eq $false) {
 148                 $ast = $a3 ? $a3 : $nil;
 149             } else {
 150                 $ast = $a2;
 151             }
 152             # Continue loop (TCO)
 153         }
 154         when (/^fn\*$/) {
 155             return Function->new(\&EVAL, $a2, $env, $a1);
 156         }
 157         default {
 158             my $el = eval_ast($ast, $env);
 159             my $f = $el->nth(0);
 160             if ((ref $f) =~ /^Function/) {
 161                 $ast = $f->{ast};
 162                 $env = $f->gen_env($el->rest());
 163                 # Continue loop (TCO)
 164             } else {
 165                 return &{ $f }($el->rest());
 166             }
 167         }
 168     }
 169
 170     } # TCO while loop
 171 }
 172
 173 # print
 174 sub PRINT {
 175     my $exp = shift;
 176     return printer::_pr_str($exp);
 177 }
 178
 179 # repl
 180 my $repl_env = Env->new();
 181 sub REP {
 182     my $str = shift;
 183     return PRINT(EVAL(READ($str), $repl_env));
 184 }
 185
 186 # core.pl: defined using perl
 187 foreach my $n (%$core_ns) {
 188     $repl_env->set(Symbol->new($n), $core_ns->{$n});
 189 }
 190 $repl_env->set(Symbol->new('eval'), sub { EVAL($_[0]->nth(0), $repl_env); });
 191 my @_argv = map {String->new($_)}  @ARGV[1..$#ARGV];
 192 $repl_env->set(Symbol->new('*ARGV*'), List->new(\@_argv));
 193
 194 # core.mal: defined using the language itself
 195 REP("(def! not (fn* (a) (if a false true)))");
 196 REP("(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \")\")))))");
 197 REP("(defmacro! cond (fn* (& xs) (if (> (count xs) 0) (list 'if (first xs) (if (> (count xs) 1) (nth xs 1) (throw \"odd number of forms to cond\")) (cons 'cond (rest (rest xs)))))))");
 198 REP("(defmacro! or (fn* (& xs) (if (empty? xs) nil (if (= 1 (count xs)) (first xs) `(let* (or_FIXME ~(first xs)) (if or_FIXME or_FIXME (or ~@(rest xs))))))))");
 199
 200
 201 if (scalar(@ARGV) > 0 && $ARGV[0] eq "--raw") {
 202     set_rl_mode("raw");
 203     shift @ARGV;
 204 }
 205 if (scalar(@ARGV) > 0) {
 206     REP("(load-file \"" . $ARGV[0] . "\")");
 207     exit 0;
 208 }
 209 while (1) {
 210     my $line = mal_readline("user> ");
 211     if (! defined $line) { last; }
 212     do {
 213         local $@;
 214         my $ret;
 215         eval {
 216             use autodie; # always "throw" errors
 217             print(REP($line), "\n");
 218             1;
 219         } or do {
 220             my $err = $@;
 221             given (ref $err) {
 222                 when (/^BlankException/) {
 223                     # ignore and continue
 224                 }
 225                 default {
 226                     chomp $err;
 227                     print "Error: $err\n";
 228                 }
 229             }
 230         };
 231     };
 232 }