Ruby: step4_if_fn_do with core functions.

7 files changed, 125 insertions, 7 deletions

diff --git a/ruby/core.rb b/ruby/core.rb
new file mode 100644
index 0000000..268ebad
--- /dev/null
+++ b/ruby/core.rb
@@ -0,0 +1,20 @@
+$core_ns = {
+    :"=" =>       lambda {|a,b| a == b},
+    :"pr-str" =>  lambda {|*a| a.map {|e| _pr_str(e, true)}.join(" ")},
+    :"str" =>     lambda {|*a| a.map {|e| _pr_str(e, false)}.join("")},
+    :"prn" =>     lambda {|*a| puts(a.map {|e| _pr_str(e, true)}.join(" "))},
+    :"println" => lambda {|*a| puts(a.map {|e| _pr_str(e, false)}.join(" "))},
+    :< =>         lambda {|a,b| a < b},
+    :<= =>        lambda {|a,b| a <= b},
+    :> =>         lambda {|a,b| a > b},
+    :>= =>        lambda {|a,b| a >= b},
+    :+ =>         lambda {|a,b| a + b},
+    :- =>         lambda {|a,b| a - b},
+    :* =>         lambda {|a,b| a * b},
+    :/ =>         lambda {|a,b| a / b},
+    :list =>      lambda {|*a| List.new a},
+    :list? =>     lambda {|*a| a[0].is_a? List},
+    :empty? =>    lambda {|a| a.size == 0},
+    :count =>     lambda {|a| a.size},
+}
+
diff --git a/ruby/env.rb b/ruby/env.rb
index dfd5ec9..97dfa13 100644
--- a/ruby/env.rb
+++ b/ruby/env.rb
@@ -3,6 +3,15 @@ class Env
     def initialize(outer=nil, binds=[], exprs=[])
         @data = {}
         @outer = outer
+        binds.each_index do |i|
+            if binds[i] == :"&"
+                data[binds[i+1]] = exprs.drop(i)
+                break
+            else
+                data[binds[i]] = exprs[i]
+            end
+        end
+        return self
     end
 
     def find(key)
diff --git a/ruby/printer.rb b/ruby/printer.rb
index 2d46e07..424ca23 100644
--- a/ruby/printer.rb
+++ b/ruby/printer.rb
@@ -9,9 +9,7 @@ def _pr_str(obj, print_readably=true)
             "[" + obj.map{|x| _pr_str(x, _r)}.join(" ") + "]"
         when String
             if _r
-                "\"" + obj.gsub(/\\/, "\\\\") \
-                          .gsub(/"/, "\\\\\"") \
-                          .gsub(/\n/, "\\\\n") + "\""
+                obj.inspect  # escape special characters
             else
                 obj
             end
diff --git a/ruby/reader.rb b/ruby/reader.rb
index d224e9c..0c113e3 100644
--- a/ruby/reader.rb
+++ b/ruby/reader.rb
@@ -21,7 +21,7 @@ def tokenize(str)
 end
 
 def parse_str(t)
-    return t[1..-2].gsub(/\\"/, "\"").gsub(/\\n/, "\n")
+    return t[1..-2].gsub(/\\"/, '"').gsub(/\\n/, "\n") # unescape
 end
 
 def read_atom(rdr)
diff --git a/ruby/step3_env.rb b/ruby/step3_env.rb
index 97be81d..9d1c373 100644
--- a/ruby/step3_env.rb
+++ b/ruby/step3_env.rb
@@ -31,12 +31,13 @@ def EVAL(ast, env)
     # apply list
     a0,a1,a2,a3 = ast
     case a0
-    when :"def!"
+    when :def!
         return env.set(a1, EVAL(a2, env))
     when :"let*"
         let_env = Env.new(env)
-        
-        a1.each_slice(2) {|a,e| let_env.set(a, EVAL(e, let_env))}
+        a1.each_slice(2) do |a,e|
+            let_env.set(a, EVAL(e, let_env))
+        end
         return EVAL(a2, let_env)
     else
         el = eval_ast(ast, env)
diff --git a/ruby/step4_if_fn_do.rb b/ruby/step4_if_fn_do.rb
new file mode 100644
index 0000000..e2e3e29
--- /dev/null
+++ b/ruby/step4_if_fn_do.rb
@@ -0,0 +1,89 @@
+require "readline"
+require "types"
+require "reader"
+require "printer"
+require "env"
+require "core"
+
+# read
+def READ(str)
+    return read_str(str)
+end
+
+# eval
+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)
+    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 :do
+        el = eval_ast(ast.drop(1), env)
+        return el.last
+    when :if
+        cond = EVAL(a1, env)
+        if not cond
+            return nil if a3 == nil
+            return EVAL(a3, env)
+        else
+            return EVAL(a2, env)
+        end
+    when :"fn*"
+        return lambda {|*args|
+            EVAL(a2, Env.new(env, a1, args))
+        }
+    else
+        el = eval_ast(ast, env)
+        f = el[0]
+        return f[*el.drop(1)]
+    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
+
+# Defined using the language itself
+RE["(def! not (fn* (a) (if a false true)))"]
+
+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 a7ce285..02ca7a6 100644
--- a/ruby/types.rb
+++ b/ruby/types.rb
@@ -3,3 +3,4 @@ end
 
 class Vector < Array
 end
+