3 files changed, 138 insertions, 0 deletions
diff --git a/ruby/reader.rb b/ruby/reader.rb
index eddb319..d6d9b8d 100644
--- a/ruby/reader.rb
+++ b/ruby/reader.rb
@@ -59,6 +59,10 @@ def read_form(rdr)
     token = rdr.peek
     return case rdr.peek
         when ";" then  nil
+        when "'" then  rdr.next; List.new [:quote, read_form(rdr)]
+        when "`" then  rdr.next; List.new [:quasiquote, read_form(rdr)]
+        when "~" then  rdr.next; List.new [:unquote, read_form(rdr)]
+        when "~@" then rdr.next; List.new [:"splice-unquote", read_form(rdr)]
         when "(" then  read_list(rdr, List, "(", ")")
         when ")" then  raise "unexpected ')'"
         when "[" then  read_list(rdr, Vector, "[", "]")
diff --git a/ruby/step7_quote.rb b/ruby/step7_quote.rb
new file mode 100644
index 0000000..6e6acca
--- /dev/null
+++ b/ruby/step7_quote.rb
@@ -0,0 +1,130 @@
+require "readline"
+require "types"
+require "reader"
+require "printer"
+require "env"
+require "core"
+
+# read
+def READ(str)
+    return read_str(str)
+end
+
+# eval
+def pair?(x)
+    return sequential?(x) && x.size > 0
+end
+
+def quasiquote(ast)
+    if not pair?(ast)
+        return List.new [:quote, ast]
+    elsif ast[0] == :unquote
+        return ast[1]
+    elsif pair?(ast[0]) && ast[0][0] == :"splice-unquote"
+        return List.new [:concat, ast[0][1], quasiquote(ast.drop(1))]
+    else
+        return List.new [:cons, quasiquote(ast[0]), quasiquote(ast.drop(1))]
+    end
+end
+
+def eval_ast(ast, env)
+    return case ast
+        when Symbol
+            env.get(ast)
+        when List   
+            List.new ast.map{|a| EVAL(a, env)}
+        when Vector
+            Vector.new ast.map{|a| EVAL(a, env)}
+        else 
+            ast
+    end
+end
+
+def EVAL(ast, env)
+    while true
+
+    if not ast.is_a? List
+        return eval_ast(ast, env)
+    end
+
+    # apply list
+    a0,a1,a2,a3 = ast
+    case a0
+    when :def!
+        return env.set(a1, EVAL(a2, env))
+    when :"let*"
+        let_env = Env.new(env)
+        a1.each_slice(2) do |a,e|
+            let_env.set(a, EVAL(e, let_env))
+        end
+        return EVAL(a2, let_env)
+    when :quote
+        return a1
+    when :quasiquote
+        return EVAL(quasiquote(a1), env)
+    when :do
+        eval_ast(ast[1..-2], env)
+        ast = ast.last
+    when :if
+        cond = EVAL(a1, env)
+        if not cond
+            return nil if a3 == nil
+            ast = a3
+        else
+            ast = a2
+        end
+    when :"fn*"
+        return Function.new(a2, env, a1) {|*args|
+            EVAL(a2, Env.new(env, a1, args))
+        }
+    else
+        el = eval_ast(ast, env)
+        f = el[0]
+        if f.class == Function
+            ast = f.ast
+            env = f.gen_env(el.drop(1))
+        else
+            return f[*el.drop(1)]
+        end
+    end
+
+    end
+end
+
+# print
+def PRINT(exp)
+    return _pr_str(exp, true)
+end
+
+# repl
+repl_env = Env.new
+RE = lambda {|str| EVAL(READ(str), repl_env) }
+REP = lambda {|str| PRINT(EVAL(READ(str), repl_env)) }
+_ref = lambda {|k,v| repl_env.set(k, v) }
+
+# Import core functions
+$core_ns.each &_ref
+
+_ref[:"read-string", lambda {|str| read_str str}]
+_ref[:eval, lambda {|ast| EVAL(ast, repl_env)}]
+_ref[:slurp, lambda {|f| File.read(f) }]
+
+# Defined using the language itself
+RE["(def! not (fn* (a) (if a false true)))"]
+RE["(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \")\")))))"]
+
+p Dir.pwd
+if ARGV.size > 0
+    ARGV.each {|f|
+        RE["(load-file \"" + f + "\")"]
+    }
+    exit 0
+end
+while line = Readline.readline("user> ", true)
+    begin
+        puts REP[line]
+    rescue Exception => e
+        puts "Error: #{e}" 
+        puts "\t#{e.backtrace.join("\n\t")}"
+    end
+end
diff --git a/ruby/types.rb b/ruby/types.rb
index 16d8d1e..6f22041 100644
--- a/ruby/types.rb
+++ b/ruby/types.rb
@@ -6,6 +6,10 @@ end
 class Vector < Array
 end
 
+def sequential?(obj)
+    return obj.is_a?(List) || obj.is_a?(Vector)
+end
+
 class Function < Proc
     attr_accessor :ast
     attr_accessor :env