diff --git a/core.nom b/core.nom
index 830e312..810859c 100644
--- a/core.nom
+++ b/core.nom
@@ -115,13 +115,6 @@ rule "%a != %b":
 rule "say %str":
     lua block ["print(utils.repr(", %str, "))"]
 
-rule "printf %str":
-    lua block ".."
-        |for _,s in ipairs(vars.str) do
-        |    io.write(utils.repr(s))
-        |end
-        |io.write("\n")
-
 rule "do %action":
     lua expr "vars.action(compiler, setmetatable({}, {__index=vars}))"
 
@@ -161,6 +154,7 @@ macro block "for %varname in %iterable %body":
         "\n    vars[", %varname, "] = old_loopval"
         "\nend"
 
+
 rule "%start up to %stop":
     lua expr "utils.range(vars.start,vars.stop-1)"
 
diff --git a/examples/sample_code.nom b/examples/sample_code.nom
index 63078d7..2917be1 100644
--- a/examples/sample_code.nom
+++ b/examples/sample_code.nom
@@ -104,12 +104,11 @@ if %x:
     say "three"
 
 
-printf [..]
-    ".."
-        |this is a longstring
-        |
-    .., "with", ".."
-        | multiple lines
+say ".."
+    |this is a longstring
+    |
+    |   with multiple lines
+    |   and an interpolated expression: \2 + 5\
 
 rule "%n bottles":
     lua block [..]
diff --git a/examples/sample_game.nom b/examples/sample_game.nom
index 8ac7e7a..52137d2 100644
--- a/examples/sample_game.nom
+++ b/examples/sample_game.nom
@@ -89,7 +89,8 @@ with everyone's approval:
         ..else:
             let "approvers" = (number of (* %pending = "approved"))
             let "num-players" = (number of (players))
-            printf [%approvers, "/", %num-players, " players have approved"]
+            say ".."
+                |\number of (* %pending = "approved")\/\number of (players)\ players have approved.
 
     rule ["reject", "vote no", "vote nay", "veto", "disapprove"]:
         let "pending" = ("pending proposal" "is" ?)
@@ -104,7 +105,8 @@ with everyone's approval:
 
     rule "join":
         (you) "is a player" = (yes)
-        printf ["Welcome to the game, ", you,"!"]
+        say ".."
+            |Welcome to the game, \you\!
 
     allow "unpropose" to use "set all * % = %"
     allow ["join", "mark % as approving %", "mark % as rejecting %", "propose %", "unpropose"] to use "% % = %"
@@ -149,9 +151,11 @@ propose:
     rule "vote for %candidate":
         (you) "votes for" = %candidate
         let "vote-percent" = ((number of (* "votes for" = %candidate)) / (number of (players)))
-        printf ["Vote cast. ",%candidate," now has ",(100 * %vote-percent),"% of the votes."]
+        say ".."
+            |Vote cast. \%candidate\ now has \100 * %vote-percent\% of the votes.
         if (%vote-percent > 0.5):
-            printf ["The winner of the election is:", %candidate]
+            say ".."
+                |The winner of the election is: \%candidate\
             close the election
 
     allow ["open election %", "close the election", "vote for %"] to use ["% % = %"]
@@ -163,7 +167,8 @@ propose:
         if ((you) == "Anonymous"):
             make "bill" do %action
         ..else:
-            printf ["Who do you think you are, ", you,"?"]
+            say ".."
+                |Who do you think you are, \you\?
     allow ["as bill %"] to use ["make % %"]
 approve
 as bill: join
@@ -173,7 +178,8 @@ propose:
         if ((you) == "Anonymous"):
             make "dave" do %action
         ..else:
-            printf ["Who do you think you are, ", you,"?"]
+            say ".."
+                |Who do you think you are, \you\?
     allow ["as dave %"] to use ["make % %"]
 approve
 as bill: approve
diff --git a/examples/tutorial.nom b/examples/tutorial.nom
index 4a9c213..14a487f 100644
--- a/examples/tutorial.nom
+++ b/examples/tutorial.nom
@@ -13,8 +13,7 @@ run file "core.nom"
 
 # Strings:
 "asdf"
-".."
-    |This is a multi-line string with a #.. fake comment
+".."|This is a multi-line string with a #.. fake comment
     |that starts with ".." and includes each indented line that starts with a "|"
     |until the indentation ends
 
@@ -101,14 +100,22 @@ say both ".."
     "-- Abraham Lincoln"
 
 rule "my favorite number": return 23
+
 # Subexpressions are wrapped in parentheses:
-# printf takes a list of bits that are converted to strings and concatenated together, and printed
-printf ["My favorite number is ", my favorite number]
+say (my favorite number)
 # There's a multi-line indented block form for subexpressions too:
-printf [..]
-    "My favorite number is still ", (..)
+say (..)
+    my favorite
+    number
+
+# Block strings can interpolate values by enclosing an expression in a pair of \s
+say ".."|My favorite number is \my favorite number\!
+
+say ".."
+    |My favorite number is still \(..)
         my favorite
         number
+    ..\, but this time it uses an indented subexpression!
 
 #.. There's a few macros in the language for things like conditional branches and logic/math
     operations, but they can be thought of as basically the same as functions.
@@ -146,17 +153,15 @@ if (1 > 10):
 let "numbers" = [5,6,7]
 
 # Looping: 
-printf ["Looping over: ",%numbers,"!"]
+say ".."|Looping over \%numbers\:
 for "number" in %numbers:
     say (%number + 100)
 
 rule "sing %starting-bottles bottles of beer":
     for "n" in (%starting-bottles down through 0):
-        printf [..]
-            (%n if (%n > 0) else "No more")
-            (" bottle" if (%n == 1) else " bottles")
-            " of beer on the wall."
-            ("" if (%n == 0) else " Take one down, pass it around...")
+        say ".."
+            |\%n if (%n > 0) else "No more"\ \"bottle" if (%n == 1) else "bottles"\ of beer on the wall.
+            |\"" if (%n == 0) else "    Take one down, pass it around..."\
 
 sing 9 bottles of beer
 
@@ -182,25 +187,23 @@ any of [0,0,0,0,1,0,0]
 rule "say the time":
     lua block ".."
         |io.write("The OS time is: ")
-        |io.write(tostring(os.time()).."\n")
+        |io.write(tostring(os.time()).."\\n")
 say the time
-printf ["Math expression result is: ", lua expr "(1 + 2*3 + 3*4)^2"]
+say ".."|Math expression result is: \lua expr "(1 + 2*3 + 3*4)^2"\
 
 #.. In the lua environment, "vars" can be used to get local variables/function args, and
     "compiler" can be used to access the compiler, function defs, and other things
 rule "square root of %n":
     return (lua expr "math.sqrt(vars.n)")
-printf ["the square root of 2 is ", square root of 2]
+say ".."|The square root of 2 is \square root of 2\
 
 # Macros can be defined as functions that take unprocessed syntax trees and return lua code 
 # "macro block %" is for defining macros that produce blocks of code, not values 
 macro block "unless %condition %body":
-    concat [..]
-        # "% as lua expr" and "% as lua block" are two useful helper functions here. 
-        "if not (", %condition as lua expr, ") then"
-        # Extract the inner part of the code block's body and insert it: 
-        "\n    ", (lua expr "vars.body.value.value") as lua block
-        "\nend"
+    ".."
+        |if not (\%condition as lua expr\) then
+        |    \(lua expr "vars.body.value.value") as lua block\
+        |end
 
 unless (1 > 10):
     say "Macros work!"
@@ -208,6 +211,6 @@ unless (1 > 10):
 
 # and "macro %" is for defining macros that produce an expression 
 macro "%value as a boolean":
-    concat ["(not not (", %value as lua expr, "))"]
+    ".."|(not not (\%value as lua expr\))
 macro "yep": "true"
 
diff --git a/nomsu.lua b/nomsu.lua
index dfe4459..2abf7da 100644
--- a/nomsu.lua
+++ b/nomsu.lua
@@ -59,7 +59,7 @@ make_parser = function(lingo, extra_definitions)
     end
     return end_pos
   end
-  local wordchar = P(1) - S(' \t\n\r%#:;,.{}[]()"')
+  local wordchar = P(1) - S(' \t\n\r%#:;,.{}[]()"\\')
   local nl = P("\n")
   local whitespace = S(" \t") ^ 1
   local blank_line = whitespace ^ -1 * nl
@@ -288,7 +288,17 @@ do
             expression <- ({ (longstring / string / number / variable / list / thunk / subexpression) }) -> Expression
 
             string <- ({ (!longstring) '"' {(("\" [^%nl]) / [^"%nl])*} '"' }) -> String
-            longstring <- ({ '".."' %ws? %line_comment? %indent {(%new_line "|" [^%nl]*)+} ((%dedent (%new_line '..')?) / errors) }) -> Longstring
+            longstring <- ({ '".."' %ws?
+                {|
+                    (("|" {| ({("\\" / (!string_interpolation [^%nl]))+} / string_interpolation)* |})
+                     / %line_comment)?
+                    (%indent
+                        (%new_line "|" {|
+                            ({("\\" / (!string_interpolation [^%nl]))+} / string_interpolation)*
+                        |})+
+                    ((%dedent (%new_line '..')?) / errors))?
+                |}}) -> Longstring
+            string_interpolation <- "\" %ws? (functioncall / expression) %ws? "\"
             number <- ({ {'-'? [0-9]+ ("." [0-9]+)?} }) -> Number
             variable <- ({ ("%" {%wordchar+}) }) -> Var
 
@@ -314,13 +324,13 @@ do
       assert(tree, "Failed to parse: " .. tostring(str))
       return tree
     end,
-    tree_to_value = function(self, tree)
-      local code = "return (function(compiler, vars)\nreturn " .. tostring(self:tree_to_lua(tree)) .. "\nend)"
+    tree_to_value = function(self, tree, vars)
+      local code = "\n        local utils = require('utils')\n        return (function(compiler, vars)\nreturn " .. tostring(self:tree_to_lua(tree)) .. "\nend)"
       local lua_thunk, err = load(code)
       if not lua_thunk then
         error("Failed to compile generated code:\n" .. tostring(code) .. "\n\n" .. tostring(err))
       end
-      return (lua_thunk())(self, { })
+      return (lua_thunk())(self, vars or { })
     end,
     tree_to_lua = function(self, tree, kind)
       if kind == nil then
@@ -347,9 +357,9 @@ do
         for _index_0 = 1, #_list_0 do
           local statement = _list_0[_index_0]
           local code = to_lua(statement)
-          local lua_thunk, err = load("return (function(compiler, vars)\n" .. tostring(code) .. "\nend)")
+          local lua_thunk, err = load("\n                    local utils = require('utils')\n                    return (function(compiler, vars)\n" .. tostring(code) .. "\nend)")
           if not lua_thunk then
-            error("Failed to compile generated code:\n" .. tostring(code) .. "\n\n" .. tostring(err))
+            error("Failed to compile generated code:\n" .. tostring(code) .. "\n\n" .. tostring(err) .. "\n\nProduced by statement:\n" .. tostring(utils.repr(statement)))
           end
           local ok
           ok, err = pcall(lua_thunk)
@@ -429,17 +439,35 @@ do
         end))
         add(utils.repr(unescaped, true))
       elseif "Longstring" == _exp_0 then
-        local result
-        do
-          local _accum_0 = { }
-          local _len_0 = 1
-          for line in tree.value:gmatch("[ \t]*|([^\n]*)") do
-            _accum_0[_len_0] = line
-            _len_0 = _len_0 + 1
+        local concat_parts = { }
+        local string_buffer = ""
+        for i, line in ipairs(tree.value) do
+          if i > 1 then
+            string_buffer = string_buffer .. "\n"
+          end
+          for _index_0 = 1, #line do
+            local bit = line[_index_0]
+            if type(bit) == "string" then
+              string_buffer = string_buffer .. bit:gsub("\\\\", "\\")
+            else
+              if string_buffer ~= "" then
+                table.insert(concat_parts, utils.repr(string_buffer, true))
+                string_buffer = ""
+              end
+              table.insert(concat_parts, "utils.repr(" .. tostring(to_lua(bit)) .. ")")
+            end
           end
-          result = _accum_0
         end
-        add(utils.repr(table.concat(result, "\n"), true))
+        if string_buffer ~= "" then
+          table.insert(concat_parts, utils.repr(string_buffer, true))
+        end
+        if #concat_parts == 0 then
+          add("''")
+        elseif #concat_parts == 1 then
+          add(concat_parts[1])
+        else
+          add("(" .. tostring(table.concat(concat_parts, "..")) .. ")")
+        end
       elseif "Number" == _exp_0 then
         add(tree.value)
       elseif "List" == _exp_0 then
@@ -670,34 +698,12 @@ do
     end,
     initialize_core = function(self)
       local as_lua_code
-      as_lua_code = function(self, str)
+      as_lua_code = function(self, str, vars)
         local _exp_0 = str.type
         if "String" == _exp_0 then
-          local escapes = {
-            n = "\n",
-            t = "\t",
-            b = "\b",
-            a = "\a",
-            v = "\v",
-            f = "\f",
-            r = "\r"
-          }
-          local unescaped = str.value:gsub("\\(.)", (function(c)
-            return escapes[c] or c
-          end))
-          return unescaped
+          return self:tree_to_value(str, vars)
         elseif "Longstring" == _exp_0 then
-          local result
-          do
-            local _accum_0 = { }
-            local _len_0 = 1
-            for line in str.value:gmatch("[ \t]*|([^\n]*)") do
-              _accum_0[_len_0] = line
-              _len_0 = _len_0 + 1
-            end
-            result = _accum_0
-          end
-          return table.concat(result, "\n")
+          return self:tree_to_value(str, vars)
         else
           return self:tree_to_lua(str)
         end
@@ -715,13 +721,13 @@ do
             local _list_0 = lua_code.value
             for _index_0 = 1, #_list_0 do
               local i = _list_0[_index_0]
-              _accum_0[_len_0] = as_lua_code(self, i.value)
+              _accum_0[_len_0] = as_lua_code(self, i.value, vars)
               _len_0 = _len_0 + 1
             end
             return _accum_0
           end)()), true
         else
-          return as_lua_code(self, lua_code), true
+          return as_lua_code(self, lua_code, vars), true
         end
       end)
       self:defmacro([[lua expr %lua_code]], function(self, vars, kind)
@@ -734,13 +740,13 @@ do
             local _list_0 = lua_code.value
             for _index_0 = 1, #_list_0 do
               local i = _list_0[_index_0]
-              _accum_0[_len_0] = as_lua_code(self, i.value)
+              _accum_0[_len_0] = as_lua_code(self, i.value, vars)
               _len_0 = _len_0 + 1
             end
             return _accum_0
           end)())
         else
-          return as_lua_code(self, lua_code)
+          return as_lua_code(self, lua_code, vars)
         end
       end)
       self:def("rule %spec %body", function(self, vars)
@@ -750,15 +756,15 @@ do
         if kind == "Expression" then
           error("Macro definitions cannot be used as expressions.")
         end
-        self:defmacro(self:tree_to_value(vars.spec), self:tree_to_value(vars.body))
+        self:defmacro(self:tree_to_value(vars.spec, vars), self:tree_to_value(vars.body, vars))
         return "", true
       end)
       self:defmacro([[macro block %spec %body]], function(self, vars, kind)
         if kind == "Expression" then
           error("Macro definitions cannot be used as expressions.")
         end
-        local invocation = self:tree_to_value(vars.spec)
-        local fn = self:tree_to_value(vars.body)
+        local invocation = self:tree_to_value(vars.spec, vars)
+        local fn = self:tree_to_value(vars.body, vars)
         self:defmacro(invocation, (function(self, vars, kind)
           if kind == "Expression" then
             error("Macro: " .. tostring(invocation) .. " was defined to be a block, not an expression.")
@@ -837,7 +843,8 @@ if arg and arg[1] then
     else
       output = io.open(arg[2], 'w')
     end
-    output:write([[    local load = function()
+    output:write([[    local utils = require('utils')
+    local load = function()
     ]])
     output:write(code)
     output:write([[
diff --git a/nomsu.moon b/nomsu.moon
index d0b9723..a27354a 100755
--- a/nomsu.moon
+++ b/nomsu.moon
@@ -4,7 +4,6 @@ lpeg = require 'lpeg'
 utils = require 'utils'
 
 -- TODO:
--- string interpolation
 -- improve indentation of generated lua code
 -- provide way to run precompiled nomsu -> lua code
 -- comprehensions?
@@ -44,7 +43,7 @@ make_parser = (lingo, extra_definitions)->
         if num_spaces != indent_stack[#indent_stack] then return nil
         return end_pos
 
-    wordchar = P(1)-S(' \t\n\r%#:;,.{}[]()"')
+    wordchar = P(1)-S(' \t\n\r%#:;,.{}[]()"\\')
     nl = P("\n")
     whitespace = S(" \t")^1
     blank_line = whitespace^-1 * nl
@@ -199,7 +198,17 @@ class NomsuCompiler
             expression <- ({ (longstring / string / number / variable / list / thunk / subexpression) }) -> Expression
 
             string <- ({ (!longstring) '"' {(("\" [^%nl]) / [^"%nl])*} '"' }) -> String
-            longstring <- ({ '".."' %ws? %line_comment? %indent {(%new_line "|" [^%nl]*)+} ((%dedent (%new_line '..')?) / errors) }) -> Longstring
+            longstring <- ({ '".."' %ws?
+                {|
+                    (("|" {| ({("\\" / (!string_interpolation [^%nl]))+} / string_interpolation)* |})
+                     / %line_comment)?
+                    (%indent
+                        (%new_line "|" {|
+                            ({("\\" / (!string_interpolation [^%nl]))+} / string_interpolation)*
+                        |})+
+                    ((%dedent (%new_line '..')?) / errors))?
+                |}}) -> Longstring
+            string_interpolation <- "\" %ws? (functioncall / expression) %ws? "\"
             number <- ({ {'-'? [0-9]+ ("." [0-9]+)?} }) -> Number
             variable <- ({ ("%" {%wordchar+}) }) -> Var
 
@@ -225,12 +234,15 @@ class NomsuCompiler
         assert tree, "Failed to parse: #{str}"
         return tree
 
-    tree_to_value: (tree)=>
-        code = "return (function(compiler, vars)\nreturn #{@tree_to_lua(tree)}\nend)"
+    tree_to_value: (tree, vars)=>
+        -- TODO: clean up require utils
+        code = "
+        local utils = require('utils')
+        return (function(compiler, vars)\nreturn #{@tree_to_lua(tree)}\nend)"
         lua_thunk, err = load(code)
         if not lua_thunk
             error("Failed to compile generated code:\n#{code}\n\n#{err}")
-        return (lua_thunk!)(self, {})
+        return (lua_thunk!)(self, vars or {})
 
     tree_to_lua: (tree, kind="Expression")=>
         assert tree, "No tree provided."
@@ -251,9 +263,12 @@ class NomsuCompiler
                 for statement in *tree.value.body.value
                     code = to_lua(statement)
                     -- Run the fuckers as we go
-                    lua_thunk, err = load("return (function(compiler, vars)\n#{code}\nend)")
+                    -- TODO: clean up repeated loading of utils?
+                    lua_thunk, err = load("
+                    local utils = require('utils')
+                    return (function(compiler, vars)\n#{code}\nend)")
                     if not lua_thunk
-                        error("Failed to compile generated code:\n#{code}\n\n#{err}")
+                        error("Failed to compile generated code:\n#{code}\n\n#{err}\n\nProduced by statement:\n#{utils.repr(statement)}")
                     ok,err = pcall(lua_thunk)
                     if not ok then error(err)
                     ok,err = pcall(err, self, vars)
@@ -308,9 +323,28 @@ class NomsuCompiler
                 add utils.repr(unescaped, true)
 
             when "Longstring"
-                -- TODO: handle comments here?
-                result = [line for line in tree.value\gmatch("[ \t]*|([^\n]*)")]
-                add utils.repr(table.concat(result, "\n"), true)
+                concat_parts = {}
+                string_buffer = ""
+                for i,line in ipairs(tree.value)
+                    if i > 1 then string_buffer ..= "\n"
+                    for bit in *line
+                        if type(bit) == "string"
+                            string_buffer ..= bit\gsub("\\\\","\\")
+                        else
+                            if string_buffer ~= ""
+                                table.insert concat_parts, utils.repr(string_buffer, true)
+                                string_buffer = ""
+                            table.insert concat_parts, "utils.repr(#{to_lua(bit)})"
+
+                if string_buffer ~= ""
+                    table.insert concat_parts, utils.repr(string_buffer, true)
+
+                if #concat_parts == 0
+                    add "''"
+                elseif #concat_parts == 1
+                    add concat_parts[1]
+                else
+                    add "(#{table.concat(concat_parts, "..")})"
 
             when "Number"
                 add tree.value
@@ -482,17 +516,12 @@ class NomsuCompiler
 
     initialize_core: =>
         -- Sets up some core functionality
-        as_lua_code = (str)=>
+        as_lua_code = (str, vars)=>
             switch str.type
                 when "String"
-                    escapes = n:"\n", t:"\t", b:"\b", a:"\a", v:"\v", f:"\f", r:"\r"
-                    unescaped = str.value\gsub("\\(.)", ((c)-> escapes[c] or c))
-                    return unescaped
-
+                    return @tree_to_value(str, vars)
                 when "Longstring"
-                    -- TODO: handle comments?
-                    result = [line for line in str.value\gmatch("[ \t]*|([^\n]*)")]
-                    return table.concat(result, "\n")
+                    return @tree_to_value(str, vars)
                 else
                     return @tree_to_lua(str)
 
@@ -502,18 +531,18 @@ class NomsuCompiler
             switch lua_code.type
                 when "List"
                     -- TODO: handle subexpressions
-                    return table.concat([as_lua_code(@, i.value) for i in *lua_code.value]), true
+                    return table.concat([as_lua_code(@, i.value, vars) for i in *lua_code.value]), true
                 else
-                    return as_lua_code(@, lua_code), true
+                    return as_lua_code(@, lua_code, vars), true
 
         @defmacro [[lua expr %lua_code]], (vars, kind)=>
             lua_code = vars.lua_code.value
             switch lua_code.type
                 when "List"
                     -- TODO: handle subexpressions
-                    return table.concat([as_lua_code(@, i.value) for i in *lua_code.value])
+                    return table.concat([as_lua_code(@, i.value, vars) for i in *lua_code.value])
                 else
-                    return as_lua_code(@, lua_code)
+                    return as_lua_code(@, lua_code, vars)
 
         @def "rule %spec %body", (vars)=>
             @def vars.spec, vars.body
@@ -521,14 +550,14 @@ class NomsuCompiler
         @defmacro [[macro %spec %body]], (vars, kind)=>
             if kind == "Expression"
                 error("Macro definitions cannot be used as expressions.")
-            @defmacro @tree_to_value(vars.spec), @tree_to_value(vars.body)
+            @defmacro @tree_to_value(vars.spec, vars), @tree_to_value(vars.body, vars)
             return "", true
 
         @defmacro [[macro block %spec %body]], (vars, kind)=>
             if kind == "Expression"
                 error("Macro definitions cannot be used as expressions.")
-            invocation = @tree_to_value(vars.spec)
-            fn = @tree_to_value(vars.body)
+            invocation = @tree_to_value(vars.spec, vars)
+            fn = @tree_to_value(vars.body, vars)
             @defmacro invocation, ((vars,kind)=>
                 if kind == "Expression"
                     error("Macro: #{invocation} was defined to be a block, not an expression.")
@@ -544,6 +573,7 @@ class NomsuCompiler
 -- and "./nomsu.moon input_file.nom output_file.lua" to compile (use "-" to compile to stdout)
 if arg and arg[1]
     c = NomsuCompiler()
+    --c.debug = true
     input = io.open(arg[1])\read("*a")
     -- Kinda hacky, if run via "./nomsu.moon file.nom -", then silence print and io.write
     -- during execution and re-enable them to print out the generated source code
@@ -562,6 +592,7 @@ if arg and arg[1]
         else io.open(arg[2], 'w')
 
         output\write [[
+    local utils = require('utils')
     local load = function()
     ]]
         output\write(code)