introduce sub terms

Closes #66.

lib/_007/Parser/Actions.pm

@@ -445,6 +445,21 @@ class _007::Parser::Actions {
         die "Got something in a quasi that we didn't expect: {$/.keys}";   # should never happen
     }
 
+    method term:sub ($/) {
+        my $parameterlist = $<parameterlist>.ast;
+        my $traitlist = $<traitlist>.ast;
+        my $statementlist = $<blockoid>.ast;
+
+        my $block = Q::Block.new(:$parameterlist, :$statementlist);
+        my %static-lexpad = $*runtime.current-frame.pad;
+        self.finish-block($block);
+
+        my $outer-frame = $*runtime.current-frame;
+        my $val;
+        make Q::Term::Sub.new(:$traitlist, :$block);
+        $val = Val::Sub.new(:name("(anon)"), :$parameterlist, :$statementlist, :$outer-frame, :%static-lexpad);
+    }
+
     method unquote ($/) {
         make Q::Unquote.new(:expr($<EXPR>.ast));
     }

lib/_007/Parser/Syntax.pm

@@ -216,6 +216,15 @@ grammar _007::Parser::Syntax {
             }
         }
     }
+    token term:sub {
+        sub <.ws>
+        :my $*insub = True;
+        <.newpad>
+        '(' ~ ')' <parameterlist>
+        <traitlist>
+        <blockoid>:!s
+        <.finishpad>
+    }
 
     token propertylist { [<.ws> <property>]* % [\h* ','] <.ws> }
 

lib/_007/Q.pm

@@ -136,6 +136,22 @@ class Q::PropertyList does Q {
     has Val::Array $.properties = Val::Array.new;
 }
 
+class Q::Term::Sub does Q::Term {
+    has $.traitlist = Q::TraitList.new;
+    has $.block;
+
+    method attribute-order { <traitlist block> }
+
+    method eval($runtime) {
+        return Val::Sub.new(
+            :name("(anon)"),
+            :parameterlist($.block.parameterlist),
+            :statementlist($.block.statementlist),
+            :outer-frame($runtime.current-frame),
+        );
+    }
+}
+
 class Q::Block does Q {
     has $.parameterlist;
     has $.statementlist;

lib/_007/Runtime/Builtins.pm

@@ -399,6 +399,7 @@ class _007::Runtime::Builtins {
             Q::Term::Array,
             Q::Term::Object,
             Q::Term::Quasi,
+            Q::Term::Sub,
             Q::Trait,
             Q::TraitList,
             Q::Unquote,

t/features/subs.t

@@ -152,4 +152,15 @@ use _007::Test;
         "can assign to a parameter which hides a subroutine";
 }
 
+{
+    my $program = q:to/./;
+        my f = sub (x) { say(x) };
+        f("Mr Bond");
+        .
+
+    outputs $program,
+        "Mr Bond\n",
+        "expression subs work";
+}
+
 done-testing;