diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,15 @@
+# 0.2.0.0
+
+  * Complete implementation of folds/maps for lists
+  * Fix space leak in folds
+  * Fix line splitting (no longer discard blank lines)
+  * Dfn fix
+  * Allow escaped characters in strings
+  * Add several builtin functions
+  * Location information when reporting errors related to typeclasses
+  * Option type
+  * Selectors for tuples
+
 # 0.1.0.0
 
 * Initial release
diff --git a/COPYING b/COPYING
new file mode 100644
--- /dev/null
+++ b/COPYING
@@ -0,0 +1,661 @@
+                    GNU AFFERO GENERAL PUBLIC LICENSE
+                       Version 3, 19 November 2007
+
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+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If your software can interact with users remotely through a computer
+network, you should also make sure that it provides a way for users to
+get its source.  For example, if your program is a web application, its
+interface could display a "Source" link that leads users to an archive
+of the code.  There are many ways you could offer source, and different
+solutions will be better for different programs; see section 13 for the
+specific requirements.
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU AGPL, see
+<https://www.gnu.org/licenses/>.
diff --git a/LICENSE b/LICENSE
deleted file mode 100644
--- a/LICENSE
+++ /dev/null
@@ -1,14 +0,0 @@
-Copyright (C) 2021-2022 Vanessa McHale
-
-This program is free software: you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation, either version 3 of the License, or
-(at your option) any later version.
-
-This program is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License
-along with this program.  If not, see <http://www.gnu.org/licenses/>.
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -5,7 +5,7 @@
 
 ## From Source
 
-First, install [Rust's regex library](https://github.com/rust-lang/regex/tree/master/regex-capi#c-api-for-rusts-regex-engine).
+First, install [Rust's regex library](https://github.com/rust-lang/regex/tree/master/regex-capi#c-api-for-rusts-regex-engine). You'll need to put `librure.so` or `librure.dylib` etc. in the appropriate place.
 
 If you have [cabal](https://www.haskell.org/cabal/) and [GHC](https://www.haskell.org/ghc/) installed (perhaps via [ghcup](https://www.haskell.org/ghcup/)):
 
@@ -13,10 +13,6 @@
 cabal install jacinda
 ```
 
-# Documentation
-
-The manpages document the builtins and provide a syntax reference.
-
 # SHOCK & AWE
 
 ```
@@ -27,6 +23,42 @@
 curl -sL https://raw.githubusercontent.com/nychealth/coronavirus-data/master/latest/now-weekly-breakthrough.csv | \
     ja ',[1.0-x%y] {ix>1}{`5:f} {ix>1}{`11:f}' -F,
 ```
+
+# Documentation
+
+See the [guide](https://vmchale.github.io/jacinda/), which contains a tutorial
+on some of the features as well as examples.
+
+The manpages document the builtins and provide a syntax reference.
+
+# Status
+
+The project is in alpha stage, it doesn't necessarily work and there are many
+missing features, but the language will remain stable.
+
+It is worse than awk but it has its place and it avoids some of the painful
+imperative/scoping defects.
+
+## Missing Features & Bugs
+
+  * `sub`/`gsub` function equivalents
+  * No nested dfns
+  * Obscure renamer edge cases during evaluation
+  * Multiple folds are criminally inefficient
+  * Documentation for tuples, `Option` type
+  * `printf` formatting for floats
+  * No list literal syntax
+  * Typeclasses are not documented
+  * Type system is questionable
+  * Postfix `:f` and `:i` are handled poorly
+  * File imports/includes
+
+Intentionally missing features:
+
+  * No loops
+  * No conditionals
+
+The latter in particular I may add if necessary
 
 # Further Advantages
 
diff --git a/app/Main.hs b/app/Main.hs
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -2,6 +2,7 @@
 
 import qualified Data.ByteString      as BS
 import qualified Data.ByteString.Lazy as BSL
+import           Data.Semigroup       ((<>))
 import qualified Data.Version         as V
 import           Jacinda.File
 import           Options.Applicative
diff --git a/doc/guide.pdf b/doc/guide.pdf
new file mode 100644
Binary files /dev/null and b/doc/guide.pdf differ
diff --git a/jacinda.cabal b/jacinda.cabal
--- a/jacinda.cabal
+++ b/jacinda.cabal
@@ -1,8 +1,8 @@
 cabal-version:      2.0
 name:               jacinda
-version:            0.1.0.0
-license:            GPL-3
-license-file:       LICENSE
+version:            0.2.0.0
+license:            AGPL-3
+license-file:       COPYING
 maintainer:         vamchale@gmail.com
 author:             Vanessa McHale
 bug-reports:        https://github.com/vmchale/jacinda/issues
@@ -16,6 +16,9 @@
     CHANGELOG.md
     README.md
     man/ja.1
+    doc/guide.pdf
+    test/examples/*.jac
+    lib/*.jac
 
 source-repository head
     type:     git
@@ -30,8 +33,6 @@
         Jacinda.Ty.Const
         Jacinda.Regex
         Jacinda.File
-        Jacinda.Rename
-        Jacinda.Backend.TreeWalk
 
     build-tool-depends: alex:alex, happy:happy
     hs-source-dirs:     src
@@ -39,12 +40,14 @@
         Jacinda.Lexer
         Intern.Name
         Intern.Unique
+        Jacinda.Rename
         Jacinda.Backend.Normalize
+        Jacinda.Backend.TreeWalk
         Jacinda.Backend.Printf
         Data.List.Ext
 
     default-language:   Haskell2010
-    ghc-options:        -Wall
+    ghc-options:        -Wall -O2
     build-depends:
         base >=4.10.0.0 && <5,
         bytestring >=0.11.0.0,
@@ -80,7 +83,7 @@
     other-modules:    Paths_jacinda
     autogen-modules:  Paths_jacinda
     default-language: Haskell2010
-    ghc-options:      -Wall -rtsopts -with-rtsopts=-A100k
+    ghc-options:      -Wall -rtsopts -with-rtsopts=-A200k
     build-depends:
         base,
         jacinda-lib,
diff --git a/lib/example.jac b/lib/example.jac
new file mode 100644
--- /dev/null
+++ b/lib/example.jac
@@ -0,0 +1,10 @@
+fn sum(x) :=
+  (+)|0 x;
+
+fn map(f, x) :=
+  f"x;
+
+fn count (x) :=
+  sum (map ([:1) x);
+
+sum $1:i
diff --git a/man/ja.1 b/man/ja.1
--- a/man/ja.1
+++ b/man/ja.1
@@ -48,19 +48,22 @@
 (a -> b -> c) -> Stream a -> Stream b -> Stream c
 .TP
 \f[B]|\f[R] Ternary operator: fold
-(b -> a -> b) -> b -> Stream a -> b
+Foldable f :=> (b -> a -> b) -> b -> f a -> b
 .TP
 \f[B]\[ha]\f[R] Ternary operator: scan
 (b -> a -> b) -> b -> Stream a -> Stream b
 .TP
 \f[B]\[lq]\f[R] Binary operator: map
-a -> b -> Stream a -> Stream b
+Functor f :=> a -> b -> f a -> f b
 .TP
 \f[B][:\f[R] Unary operator: const
 a -> b -> a
 .TP
 \f[B]#.\f[R] Binary operator: filter
 (a -> Bool) -> Stream a -> Stream a
+.TP
+\f[B].\f[R] Binary operator: prior
+(a -> a -> a) -> Stream a -> Stream a
 .PP
 \f[B]max\f[R] Maximum of two values
 .PP
@@ -84,6 +87,9 @@
 \f[B]split\f[R] Split a string by regex
 Str -> Regex -> List Str
 .TP
+\f[B]splitc\f[R] Split a string on a single character
+Str -> Str -> List Str
+.TP
 \f[B]floor\f[R] Floor function
 Float -> Int
 .TP
@@ -92,6 +98,13 @@
 .PP
 \f[B]sprintf\f[R] Convert an expression to a string using the format
 string
+.TP
+\f[B]option\f[R] Option eliminator
+b -> (a -> b) -> Option a -> b
+.TP
+\f[B]match\f[R]
+Str -> Regex -> Option (Int .
+Int)
 .SS SYNTAX
 .PP
 \f[B]\[ga]n\f[R] nth field
@@ -109,10 +122,18 @@
 \f[B]#t\f[R] Boolean literal
 .PP
 \f[B]_n\f[R] Negative number
+.TP
+\f[B].n\f[R] Extract the nth value
+List a -> a
+.PP
+\f[B]->n\f[R] Get the nth element of a tuple
 .SH BUGS
 .PP
 Please report any bugs you may come across to
 https://github.com/vmchale/jacinda/issues
+.SS Limitations
+.PP
+Note that \f[C]Option\f[R] is not implemented as a functor.
 .SH COPYRIGHT
 .PP
 Copyright 2021-2022.
diff --git a/src/Jacinda/AST.hs b/src/Jacinda/AST.hs
--- a/src/Jacinda/AST.hs
+++ b/src/Jacinda/AST.hs
@@ -16,6 +16,7 @@
                    , D (..)
                    , Program (..)
                    , C (..)
+                   , N (..)
                    , mapExpr
                    , getFS
                    -- * Base functors
@@ -45,7 +46,7 @@
         | TyStream
         | TyVec
         | TyBool
-        | TyOptional
+        | TyOption
         -- TODO: tyRegex
         -- TODO: convert float to int
         deriving (Eq, Ord)
@@ -71,14 +72,14 @@
          -- TODO: type vars, products...
 
 instance Pretty TB where
-    pretty TyInteger  = "Integer"
-    pretty TyStream   = "Stream"
-    pretty TyBool     = "Bool"
-    pretty TyStr      = "Str"
-    pretty TyFloat    = "Float"
-    pretty TyDate     = "Date"
-    pretty TyVec      = "List"
-    pretty TyOptional = "Optional"
+    pretty TyInteger = "Integer"
+    pretty TyStream  = "Stream"
+    pretty TyBool    = "Bool"
+    pretty TyStr     = "Str"
+    pretty TyFloat   = "Float"
+    pretty TyDate    = "Date"
+    pretty TyVec     = "List"
+    pretty TyOption  = "Optional"
 
 instance Pretty (T a) where
     pretty (TyB _ b)        = pretty b
@@ -95,6 +96,7 @@
          | Const
          | Not -- ^ Boolean
          | At Int
+         | Select Int
          | IParse
          | FParse
          | Floor
@@ -102,20 +104,22 @@
          deriving (Eq)
 
 instance Pretty BUn where
-    pretty Tally   = "#"
-    pretty Const   = "[:"
-    pretty Not     = "!"
-    pretty (At i)  = "." <> pretty i
-    pretty IParse  = ":i"
-    pretty FParse  = ":f"
-    pretty Floor   = "floor"
-    pretty Ceiling = "ceil"
+    pretty Tally      = "#"
+    pretty Const      = "[:"
+    pretty Not        = "!"
+    pretty (At i)     = "." <> pretty i
+    pretty (Select i) = "->" <> pretty i
+    pretty IParse     = ":i"
+    pretty FParse     = ":f"
+    pretty Floor      = "floor"
+    pretty Ceiling    = "ceil"
 
 -- ternary
 data BTer = ZipW
           | Fold
           | Scan
           | Substr
+          | Option
           deriving (Eq)
 
 instance Pretty BTer where
@@ -123,6 +127,7 @@
     pretty Fold   = "|"
     pretty Scan   = "^"
     pretty Substr = "substr"
+    pretty Option = "option"
 
 -- builtin
 data BBin = Plus
@@ -143,9 +148,11 @@
           | Min
           | Max
           | Split
+          | Splitc
           | Prior
           | Filter
           | Sprintf
+          | Match
           -- TODO: floor functions, sqrt, sin, cos, exp. (power)
           deriving (Eq)
 
@@ -170,7 +177,9 @@
     pretty Prior      = "\\."
     pretty Filter     = "#."
     pretty Split      = "split"
+    pretty Splitc     = "splitc"
     pretty Sprintf    = "sprintf"
+    pretty Match      = "match"
 
 data DfnVar = X | Y deriving (Eq)
 
@@ -178,11 +187,15 @@
     pretty X = "x"
     pretty Y = "y"
 
+-- 0-ary
+data N = Ix
+       deriving (Eq)
+
 -- expression
 data E a = Column { eLoc :: a, col :: Int }
          | IParseCol { eLoc :: a, col :: Int } -- always a column
          | FParseCol { eLoc :: a, col :: Int }
-         | Field { eLoc :: a, field :: Int }
+         | Field { eLoc :: a, eField :: Int }
          | AllField { eLoc :: a } -- ^ Think @$0@ in awk.
          | AllColumn { eLoc :: a } -- ^ Think @$0@ in awk.
          | EApp { eLoc :: a, eApp0 :: E a, eApp1 :: E a }
@@ -202,12 +215,13 @@
          | BBuiltin { eLoc :: a, eBin :: BBin }
          | TBuiltin { eLoc :: a, eTer :: BTer }
          | UBuiltin { eLoc :: a, eUn :: BUn }
-         | Ix { eLoc :: a } -- only 0-ary builtin atm
+         | NBuiltin { eLoc :: a, eNil :: N }
          | Tup { eLoc :: a, esTup :: [E a] }
          | ResVar { eLoc :: a, dfnVar :: DfnVar }
          | RegexCompiled RurePtr -- holds compiled regex (after normalization)
          | Arr { eLoc :: a, elems :: V.Vector (E a) }
          | Paren { eLoc :: a, eExpr :: E a }
+         | OptionVal { eLoc :: a, eMaybe :: Maybe (E a) }
          -- TODO: regex literal
          deriving (Functor, Generic)
          -- TODO: side effects: allow since it's strict?
@@ -237,16 +251,20 @@
             | BBuiltinF a BBin
             | TBuiltinF a BTer
             | UBuiltinF a BUn
-            | IxF a
+            | NBuiltinF a N
             | TupF a [x]
             | ResVarF a DfnVar
             | RegexCompiledF RurePtr
             | ArrF a (V.Vector x)
             | ParenF a x
+            | OptionValF a (Maybe x)
             deriving (Generic, Functor, Foldable, Traversable)
 
 type instance Base (E a) = (EF a)
 
+instance Pretty N where
+    pretty Ix   = "ix"
+
 instance Pretty (E a) where
     pretty (Column _ i)                                            = "$" <> pretty i
     pretty AllColumn{}                                             = "$0"
@@ -258,6 +276,8 @@
     pretty (EApp _ (EApp _ (BBuiltin _ Max) e) e')                 = "max" <+> pretty e <+> pretty e'
     pretty (EApp _ (EApp _ (BBuiltin _ Min) e) e')                 = "min" <+> pretty e <+> pretty e'
     pretty (EApp _ (EApp _ (BBuiltin _ Split) e) e')               = "split" <+> pretty e <+> pretty e'
+    pretty (EApp _ (EApp _ (BBuiltin _ Splitc) e) e')              = "splitc" <+> pretty e <+> pretty e'
+    pretty (EApp _ (EApp _ (BBuiltin _ Match) e) e')               = "match" <+> pretty e <+> pretty e'
     pretty (EApp _ (EApp _ (BBuiltin _ Sprintf) e) e')             = "sprintf" <+> pretty e <+> pretty e'
     pretty (EApp _ (EApp _ (BBuiltin _ Map) e) e')                 = pretty e <> "\"" <> pretty e'
     pretty (EApp _ (EApp _ (BBuiltin _ b) e) e')                   = pretty e <+> pretty b <+> pretty e'
@@ -266,7 +286,9 @@
     pretty (EApp _ (EApp _ (EApp _ (TBuiltin _ Scan) e) e') e'')   = pretty e <> "^" <> pretty e' <+> pretty e''
     pretty (EApp _ (EApp _ (EApp _ (TBuiltin _ ZipW) op) e') e'')  = "," <> pretty op <+> pretty e' <+> pretty e''
     pretty (EApp _ (EApp _ (EApp _ (TBuiltin _ Substr) e) e') e'') = "substr" <+> pretty e <+> pretty e' <+> pretty e''
-    pretty (EApp _ (UBuiltin _ (At i)) e')                         = pretty e' <> "." <> pretty i
+    pretty (EApp _ (EApp _ (EApp _ (TBuiltin _ Option) e) e') e'') = "option" <+> pretty e <+> pretty e' <+> pretty e''
+    pretty (EApp _ (UBuiltin _ (At i)) e)                          = pretty e <> "." <> pretty i
+    pretty (EApp _ (UBuiltin _ (Select i)) e)                      = pretty e <> "->" <> pretty i
     pretty (EApp _ (UBuiltin _ IParse) e')                         = pretty e' <> ":i"
     pretty (EApp _ (UBuiltin _ FParse) e')                         = pretty e' <> ":f"
     pretty (EApp _ e@UBuiltin{} e')                                = pretty e <> pretty e'
@@ -286,11 +308,13 @@
     pretty (Dfn _ e)                                               = brackets (pretty e)
     pretty (Guarded _ p e)                                         = braces (pretty p) <> braces (pretty e)
     pretty (Implicit _ e)                                          = braces ("|" <+> pretty e)
-    pretty Ix{}                                                    = "ix"
+    pretty (NBuiltin _ n)                                          = pretty n
     pretty RegexCompiled{}                                         = error "Nonsense."
     pretty (Let _ (n, b) e)                                        = "let" <+> "val" <+> pretty n <+> ":=" <+> pretty b <+> "in" <+> pretty e <+> "end"
     pretty (Paren _ e)                                             = parens (pretty e)
     pretty (Arr _ es)                                              = tupledByFunky "," (V.toList $ pretty <$> es)
+    pretty (OptionVal  _ (Just e))                                 = "Some" <+> pretty e
+    pretty (OptionVal _ Nothing)                                   = "None"
 
 instance Show (E a) where
     show = show . pretty
@@ -317,10 +341,10 @@
     (==) (BBuiltin _ b) (BBuiltin _ b')         = b == b'
     (==) (TBuiltin _ b) (TBuiltin _ b')         = b == b'
     (==) (UBuiltin _ unOp) (UBuiltin _ unOp')   = unOp == unOp'
+    (==) (NBuiltin _ x) (NBuiltin _ y)          = x == y
     (==) (Tup _ es) (Tup _ es')                 = es == es'
     (==) (ResVar _ x) (ResVar _ y)              = x == y
     (==) (Dfn _ f) (Dfn _ g)                    = f == g -- we're testing for lexical equivalence
-    (==) Ix{} Ix{}                              = True
     (==) RegexCompiled{} _                      = error "Cannot compare compiled regex!"
     (==) _ RegexCompiled{}                      = error "Cannot compare compiled regex!"
     (==) (Paren _ e) e'                         = e == e'
@@ -335,18 +359,23 @@
        | Functor -- ^ For map (@"@)
        | Foldable
        | IsPrintf
+       | HasField Int (T K)
        -- TODO: witherable
        deriving (Eq, Ord)
 
 instance Pretty C where
-    pretty IsNum       = "Num"
-    pretty IsEq        = "Eq"
-    pretty IsOrd       = "Ord"
-    pretty IsParseable = "Parseable"
-    pretty IsSemigroup = "Semigroup"
-    pretty Functor     = "Functor"
-    pretty Foldable    = "Foldable"
-    pretty IsPrintf    = "Printf"
+    pretty IsNum           = "Num"
+    pretty IsEq            = "Eq"
+    pretty IsOrd           = "Ord"
+    pretty IsParseable     = "Parseable"
+    pretty IsSemigroup     = "Semigroup"
+    pretty Functor         = "Functor"
+    pretty Foldable        = "Foldable"
+    pretty IsPrintf        = "Printf"
+    pretty (HasField i ty) = "HasField" <+> pretty i <+> "~" <+> pretty ty
+
+instance Show C where
+    show = show . pretty
 
 -- decl
 data D a = SetFS BS.ByteString
diff --git a/src/Jacinda/Backend/Normalize.hs b/src/Jacinda/Backend/Normalize.hs
--- a/src/Jacinda/Backend/Normalize.hs
+++ b/src/Jacinda/Backend/Normalize.hs
@@ -1,5 +1,8 @@
+{-# LANGUAGE OverloadedStrings #-}
+
 -- TODO: test this module?
 module Jacinda.Backend.Normalize ( compileR
+                                 , compileIn
                                  , eClosed
                                  , closedProgram
                                  , readDigits
@@ -9,6 +12,8 @@
                                  , mkStr
                                  , parseAsEInt
                                  , parseAsF
+                                 , the
+                                 , asTup
                                  ) where
 
 import           Control.Monad.State.Strict (State, evalState, gets, modify)
@@ -19,6 +24,7 @@
 import qualified Data.IntMap                as IM
 import           Data.Semigroup             ((<>))
 import qualified Data.Vector                as V
+import           Data.Word                  (Word8)
 import           Intern.Name
 import           Intern.Unique
 import           Jacinda.AST
@@ -26,6 +32,7 @@
 import           Jacinda.Regex
 import           Jacinda.Rename
 import           Jacinda.Ty.Const
+import           Regex.Rure                 (RureMatch (..))
 
 mkI :: Integer -> E (T K)
 mkI = IntLit tyI
@@ -56,16 +63,29 @@
           f '9' = 9
           f c   = error (c:" is not a valid digit!")
 
+the :: BS.ByteString -> Word8
+the bs = case BS.uncons bs of
+    Nothing     -> error "Empty splitc char!"
+    Just (c,"") -> c
+    Just _      -> error "Splitc takes only one char!"
+
 readFloat :: BS.ByteString -> Double
 readFloat = read . ASCII.unpack
 
 -- fill in regex with compiled.
-compileR :: E (T K)
-         -> E (T K)
+compileR :: E a
+         -> E a
 compileR = cata a where -- TODO: combine with eNorm pass?
     a (RegexLitF _ rr) = RegexCompiled (compileDefault rr)
     a x                = embed x
 
+compileIn :: Program a -> Program a
+compileIn (Program ds e) = Program (compileD <$> ds) (compileR e)
+
+compileD :: D a -> D a
+compileD d@SetFS{}       = d
+compileD (FunDecl n l e) = FunDecl n l (compileR e)
+
 desugar :: a
 desugar = error "Should have been desugared by this stage."
 
@@ -103,6 +123,30 @@
     e' <- eNorm e
     modify (mapBinds (IM.insert i e'))
 
+asTup :: Maybe RureMatch -> E (T K)
+asTup Nothing                = OptionVal undefined Nothing
+asTup (Just (RureMatch s e)) = OptionVal undefined (Just $ Tup undefined (mkI . fromIntegral <$> [s, e]))
+
+applyUn :: E (T K)
+        -> E (T K)
+        -> EvalM (E (T K))
+applyUn unOp e =
+    case eLoc unOp of
+        TyArr _ _ res -> eNorm (EApp res unOp e)
+        _             -> error "Internal error?"
+
+applyOp :: E (T K)
+        -> E (T K)
+        -> E (T K)
+        -> EvalM (E (T K))
+applyOp op e e' = eNorm (EApp undefined (EApp undefined op e) e') -- TODO: undefined??
+
+foldE :: E (T K)
+      -> E (T K)
+      -> V.Vector (E (T K))
+      -> EvalM (E (T K))
+foldE op = V.foldM' (applyOp op)
+
 -- TODO: equality on tuples, lists
 eNorm :: E (T K)
       -> EvalM (E (T K))
@@ -125,7 +169,7 @@
 eNorm e@BBuiltin{}    = pure e
 eNorm e@TBuiltin{}    = pure e
 eNorm (Tup tys es)    = Tup tys <$> traverse eNorm es
-eNorm e@Ix{}          = pure e
+eNorm e@(NBuiltin _ Ix) = pure e
 eNorm (EApp ty op@BBuiltin{} e) = EApp ty op <$> eNorm e
 eNorm (EApp ty (EApp ty' op@(BBuiltin _ Matches) e) e') = do
     eI <- eNorm e
@@ -145,7 +189,7 @@
     eI <- eNorm e
     eI' <- eNorm e'
     pure $ case (eI, eI') of
-        (IntLit _ i, IntLit _ j) -> IntLit tyI (i+j)
+        (IntLit _ i, IntLit _ j) -> i `seq` j `seq` IntLit tyI (i+j)
         _                        -> EApp ty0 (EApp ty1 op eI) eI'
 eNorm (EApp ty (EApp ty' op@(BBuiltin (TyArr _ (TyB _ TyStr) _) Plus) e) e') = do
     eI <- eNorm e
@@ -158,32 +202,38 @@
     eI <- eNorm e
     eI' <- eNorm e'
     pure $ case (eI, eI') of
-        (IntLit _ i, IntLit _ j) -> IntLit tyI (max i j)
+        (IntLit _ i, IntLit _ j) -> i `seq` j `seq` IntLit tyI (max i j)
         _                        -> EApp ty (EApp ty' op eI) eI'
 eNorm (EApp ty (EApp ty' op@(BBuiltin (TyArr _ (TyB _ TyInteger) _) Min) e) e') = do
     eI <- eNorm e
     eI' <- eNorm e'
     pure $ case (eI, eI') of
-        (IntLit _ i, IntLit _ j) -> IntLit tyI (min i j)
+        (IntLit _ i, IntLit _ j) -> i `seq` j `seq` IntLit tyI (min i j)
         _                        -> EApp ty (EApp ty' op eI) eI'
 eNorm (EApp ty (EApp ty' op@(BBuiltin (TyArr _ (TyB _ TyFloat) _) Max) e) e') = do
     eI <- eNorm e
     eI' <- eNorm e'
     pure $ case (eI, eI') of
-        (FloatLit _ x, FloatLit _ y) -> FloatLit tyF (max x y)
+        (FloatLit _ x, FloatLit _ y) -> x `seq` y `seq` FloatLit tyF (max x y)
         _                            -> EApp ty (EApp ty' op eI) eI'
 eNorm (EApp ty (EApp ty' op@(BBuiltin (TyArr _ (TyB _ TyFloat) _) Min) e) e') = do
     eI <- eNorm e
     eI' <- eNorm e'
     pure $ case (eI, eI') of
-        (FloatLit _ x, FloatLit _ y) -> FloatLit tyF (min x y)
+        (FloatLit _ x, FloatLit _ y) -> x `seq` y `seq` FloatLit tyF (min x y)
         _                            -> EApp ty (EApp ty' op eI) eI'
 eNorm (EApp ty (EApp ty' op@(BBuiltin _ Split) e) e') = do
     eI <- eNorm e
     eI' <- eNorm e'
     pure $ case (eI, eI') of
-        (StrLit l str, RegexCompiled re) -> let bss = splitBy re str in Arr l (StrLit l <$> bss) -- FIXME type of Arr (l) is wrong
+        (StrLit l str, RegexCompiled re) -> let bss = splitBy re str in Arr undefined (StrLit l <$> bss)
         _                                -> EApp ty (EApp ty' op eI) eI'
+eNorm (EApp ty (EApp ty' op@(BBuiltin _ Splitc) e) e') = do
+    eI <- eNorm e
+    eI' <- eNorm e'
+    pure $ case (eI, eI') of
+        (StrLit l str, StrLit _ c) -> let bss = BS.split (the c) str in Arr undefined (StrLit l <$> V.fromList bss)
+        _                          -> EApp ty (EApp ty' op eI) eI'
 eNorm (EApp ty op@(UBuiltin _ Floor) e) = do
     eI <- eNorm e
     pure $ case eI of
@@ -198,37 +248,37 @@
     eI <- eNorm e
     eI' <- eNorm e'
     pure $ case (eI, eI') of
-        (IntLit _ i, IntLit _ j) -> IntLit tyI (i-j)
+        (IntLit _ i, IntLit _ j) -> i `seq` j `seq` IntLit tyI (i-j)
         _                        -> EApp ty0 (EApp ty1 op eI) eI'
 eNorm (EApp ty (EApp ty' op@(BBuiltin (TyArr _ (TyB _ TyInteger) _) Times) e) e') = do
     eI <- eNorm e
     eI' <- eNorm e'
     pure $ case (eI, eI') of
-        (IntLit _ i, IntLit _ j) -> IntLit tyI (i*j)
+        (IntLit _ i, IntLit _ j) -> i `seq` j `seq` IntLit tyI (i*j)
         _                        -> EApp ty (EApp ty' op eI) eI'
 eNorm (EApp ty (EApp ty' op@(BBuiltin (TyArr _ (TyB _ TyFloat) _) Plus) e) e') = do
     eI <- eNorm e
     eI' <- eNorm e'
     pure $ case (eI, eI') of
-        (FloatLit _ i, FloatLit _ j) -> FloatLit tyF (i+j)
+        (FloatLit _ i, FloatLit _ j) -> i `seq` j `seq` FloatLit tyF (i+j)
         _                            -> EApp ty (EApp ty' op eI) eI'
 eNorm (EApp ty (EApp ty' op@(BBuiltin (TyArr _ (TyB _ TyFloat) _) Minus) e) e') = do
     eI <- eNorm e
     eI' <- eNorm e'
     pure $ case (eI, eI') of
-        (FloatLit _ i, FloatLit _ j) -> FloatLit tyF (i-j)
+        (FloatLit _ i, FloatLit _ j) -> i `seq` j `seq` FloatLit tyF (i-j)
         _                            -> EApp ty (EApp ty' op eI) eI'
 eNorm (EApp ty (EApp ty' op@(BBuiltin (TyArr _ (TyB _ TyFloat) _) Times) e) e') = do
     eI <- eNorm e
     eI' <- eNorm e'
     pure $ case (eI, eI') of
-        (FloatLit _ i, FloatLit _ j) -> FloatLit tyF (i*j)
+        (FloatLit _ i, FloatLit _ j) -> i `seq` j `seq` FloatLit tyF (i*j)
         _                            -> EApp ty (EApp ty' op eI) eI'
 eNorm (EApp ty (EApp ty' op@(BBuiltin (TyArr _ (TyB _ TyFloat) _) Div) e) e') = do
     eI <- eNorm e
     eI' <- eNorm e'
     pure $ case (eI, eI') of
-        (FloatLit _ i, FloatLit _ j) -> FloatLit tyF (i/j)
+        (FloatLit _ i, FloatLit _ j) -> i `seq` j `seq` FloatLit tyF (i/j)
         _                            -> EApp ty (EApp ty' op eI) eI'
 eNorm (EApp ty (UBuiltin ty' Tally) e) = do
     eI <- eNorm e
@@ -323,13 +373,13 @@
     eI <- eNorm e
     eI' <- eNorm e'
     pure $ case (eI, eI') of
-        (BoolLit _ b, BoolLit _ b') -> BoolLit tyBool (b && b')
+        (BoolLit _ b, BoolLit _ b') -> b `seq` b' `seq` BoolLit tyBool (b && b')
         _                           -> EApp ty0 (EApp ty1 op eI) eI'
 eNorm (EApp ty0 (EApp ty1 op@(BBuiltin _ Or) e) e') = do
     eI <- eNorm e
     eI' <- eNorm e'
     pure $ case (eI, eI') of
-        (BoolLit _ b, BoolLit _ b') -> BoolLit tyBool (b || b')
+        (BoolLit _ b, BoolLit _ b') -> b `seq` b' `seq` BoolLit tyBool (b || b')
         _                           -> EApp ty0 (EApp ty1 op eI) eI'
 eNorm (EApp _ (EApp _ (UBuiltin _ Const) e) _) = eNorm e
 eNorm (EApp ty op@(UBuiltin _ Const) e) = EApp ty op <$> eNorm e
@@ -338,6 +388,11 @@
     pure $ case eI of
         (Arr _ es) -> es V.! (i-1)
         _          -> EApp ty op eI
+eNorm (EApp ty op@(UBuiltin _ (Select i)) e) = do
+    eI <- eNorm e
+    pure $ case eI of
+        (Tup _ es) -> es !! (i-1)
+        _          -> EApp ty op eI
 eNorm (EApp ty op@(UBuiltin _ Not) e) = do
     eI <- eNorm e
     pure $ case eI of
@@ -377,18 +432,59 @@
     pure $ case (e0', e1', e2') of
         (StrLit _ str, IntLit _ i, IntLit _ j) -> mkStr (substr str (fromIntegral i) (fromIntegral j))
         _                                      -> EApp ty0 (EApp ty1 (EApp ty2 (TBuiltin ty3 Substr) e0') e1') e2'
+eNorm (EApp ty0 (EApp ty1 (EApp ty2 op@(TBuiltin _ Option) e0) e1) e2) = do
+    e0' <- eNorm e0
+    e1' <- eNorm e1
+    e2' <- eNorm e2
+    case e2' of
+        (OptionVal _ Nothing)  -> pure e0'
+        (OptionVal _ (Just e)) -> eNorm (EApp undefined e1' e)
+        _                      -> pure $ EApp ty0 (EApp ty1 (EApp ty2 op e0') e1') e2'
+eNorm (EApp ty0 (EApp ty1 op@(BBuiltin _ Match) e) e') = do
+    eI <- eNorm e
+    eI' <- eNorm e'
+    pure $ case (eI, eI') of
+        (StrLit _ str, RegexCompiled re) -> asTup (find' re str)
+        _                                -> EApp ty0 (EApp ty1 op eI) eI'
 eNorm (EApp ty0 (EApp ty1 op@(BBuiltin _ Sprintf) e) e') = do
     eI <- eNorm e
     eI' <- eNorm e'
-    case (eI, eI') of
-        (StrLit _ fmt, _) | isReady eI' -> pure $ mkStr $ sprintf fmt eI'
-        _                               -> EApp ty0 (EApp ty1 op eI) <$> eNorm e'
+    pure $ case (eI, eI') of
+        (StrLit _ fmt, _) | isReady eI' -> mkStr $ sprintf fmt eI'
+        _                               -> EApp ty0 (EApp ty1 op eI) eI'
+eNorm (EApp ty0 (EApp ty1 op@(BBuiltin (TyArr _ _ (TyArr _ _ (TyApp _ (TyB _ TyVec) _))) Map) x) y) = do
+    x' <- eNorm x
+    y' <- eNorm y
+    case y' of
+        Arr _ es -> Arr undefined <$> traverse (applyUn x') es -- TODO: undefined?
+        _        -> pure $ EApp ty0 (EApp ty1 op x') y'
+eNorm (EApp ty0 (EApp ty1 (EApp ty2 op@(TBuiltin (TyArr _ _ (TyArr _ _ (TyArr _ (TyApp _ (TyB _ TyVec) _) _))) Fold) f) x) y) = do
+    f' <- eNorm f
+    x' <- eNorm x
+    y' <- eNorm y
+    case y' of
+        Arr _ es -> foldE f' x' es
+        _        -> pure $ EApp ty0 (EApp ty1 (EApp ty2 op f') x') y'
+-- eNorm (EApp ty0 (EApp ty1 op@(BBuiltin (TyArr _ _ (TyArr _ _ (TyApp _ (TyB _ TyVec) _))) Prior) x) y) = do
+    -- x' <- eNorm x
+    -- y' <- eNorm y
+    -- case y' of
+        -- Arr _ es -> Arr undefined <$> V.priorM (applyOp x') es
+        -- _        -> pure $ EApp ty0 (EApp ty1 op x') y'
+-- eNorm (EApp ty0 (EApp ty1 (EApp ty2 op@(TBuiltin (TyArr _ _ (TyApp _ _ (TyApp _ (TyB _ TyVec) _))) ZipW) f) x) y) = do
+    -- f' <- eNorm f
+    -- x' <- eNorm x
+    -- y' <- eNorm y
+    -- case (x', y') of
+        -- (Arr _ es, Arr _ es') -> Arr undefined <$> V.zipWithM (applyOp f') es es'
+        -- _                     -> pure $ EApp ty0 (EApp ty1 (EApp ty2 op f') x') y'
 eNorm (EApp ty0 (EApp ty1 (EApp ty2 op@TBuiltin{} f) x) y) = EApp ty0 <$> (EApp ty1 <$> (EApp ty2 op <$> eNorm f) <*> eNorm x) <*> eNorm y
-eNorm (EApp ty0 (EApp ty1 op@(BBuiltin _ Prior) x) y) = EApp ty0 <$> (EApp ty1 op <$> eNorm x) <*> eNorm y
 eNorm (EApp ty0 (EApp ty1 op@(BBuiltin _ Map) x) y) = EApp ty0 <$> (EApp ty1 op <$> eNorm x) <*> eNorm y
+eNorm (EApp ty0 (EApp ty1 op@(BBuiltin _ Prior) x) y) = EApp ty0 <$> (EApp ty1 op <$> eNorm x) <*> eNorm y
 eNorm (EApp ty0 (EApp ty1 op@(BBuiltin _ Filter) x) y) = EApp ty0 <$> (EApp ty1 op <$> eNorm x) <*> eNorm y
 -- FIXME: this will almost surely run into trouble; if the above pattern matches
 -- are not complete it will bottom!
 eNorm (EApp ty e@EApp{} e') =
     eNorm =<< (EApp ty <$> eNorm e <*> pure e')
 eNorm (Arr ty es) = Arr ty <$> traverse eNorm es
+eNorm (OptionVal ty e) = OptionVal ty <$> traverse eNorm e
diff --git a/src/Jacinda/Backend/Printf.hs b/src/Jacinda/Backend/Printf.hs
--- a/src/Jacinda/Backend/Printf.hs
+++ b/src/Jacinda/Backend/Printf.hs
@@ -5,6 +5,7 @@
                               ) where
 
 import qualified Data.ByteString    as BS
+import           Data.Semigroup     ((<>))
 import qualified Data.Text          as T
 import           Data.Text.Encoding (decodeUtf8, encodeUtf8)
 import           Jacinda.AST
diff --git a/src/Jacinda/Backend/TreeWalk.hs b/src/Jacinda/Backend/TreeWalk.hs
--- a/src/Jacinda/Backend/TreeWalk.hs
+++ b/src/Jacinda/Backend/TreeWalk.hs
@@ -58,6 +58,10 @@
 asRegex (RegexCompiled re) = re
 asRegex _                  = noRes
 
+asArr :: E a -> V.Vector (E a)
+asArr (Arr _ es) = es
+asArr _          = noRes
+
 -- TODO: do I want to interleave state w/ eNorm or w/e
 
 -- eval
@@ -75,7 +79,7 @@
     go op@UBuiltin{} = op
     go op@TBuiltin{} = op
     go (EApp ty op@BBuiltin{} e) = EApp ty op (go e)
-    go Ix{} = mkI (fromIntegral ix)
+    go (NBuiltin _ Ix) = mkI (fromIntegral ix)
     go AllField{} = StrLit tyStr line
     go (Field _ i) = StrLit tyStr (ctx ! (i-1)) -- cause vector indexing starts at 0
     go (EApp _ (UBuiltin _ IParse) e) =
@@ -98,6 +102,10 @@
             (RegexCompiled reϵ, StrLit _ strϵ) -> BoolLit tyBool (not $ isMatch' reϵ strϵ)
             (StrLit _ strϵ, RegexCompiled reϵ) -> BoolLit tyBool (not $ isMatch' reϵ strϵ)
             _                                  -> noRes
+    go (EApp _ (EApp _ (BBuiltin _ Match) e) e') =
+        let eI = asRegex (go e)
+            eI' = asStr (go e')
+        in asTup (find' eI eI')
     go (EApp _ (EApp _ (BBuiltin (TyArr _ (TyB _ TyInteger) _) Plus) e) e') =
         let eI = asInt (go e)
             eI' = asInt (go e')
@@ -193,6 +201,11 @@
             re = asRegex (go e')
             bss = splitBy re str
             in Arr undefined (StrLit undefined <$> bss)
+    go (EApp _ (EApp _ (BBuiltin _ Splitc) e) e') =
+        let str = asStr (go e)
+            c = the (asStr (go e'))
+            bss = BS.split c str
+            in Arr undefined (StrLit undefined <$> V.fromList bss)
     go (EApp _ (EApp _ (EApp _ (TBuiltin _ Substr) e0) e1) e2) =
         let eI0 = asStr (go e0)
             eI1 = asInt (go e1)
@@ -222,10 +235,31 @@
             in case eI of
                 (Arr _ es) -> go (es V.! (i-1))
                 _          -> noRes
+    go (EApp _ (UBuiltin _ (Select i)) e) =
+        let eI = go e
+            in case eI of
+                (Tup _ es) -> go (es !! (i-1))
+                _          -> noRes
     go (EApp _ (EApp _ (BBuiltin _ Sprintf) e) e') =
         let eI = asStr (go e)
             eI' = go e'
         in mkStr (sprintf eI eI')
+    go (OptionVal ty e) =
+        OptionVal ty (go <$> e)
+    go (EApp _ (EApp _ (BBuiltin (TyArr _ _ (TyArr _ _ (TyApp _ (TyB _ TyVec) _))) Map) x) y) =
+        let x' = go x
+            y' = asArr (go y)
+        in Arr undefined (applyUn' x' <$> y')
+        where applyUn' :: E (T K) -> E (T K) -> E (T K)
+              applyUn' e e' = go (EApp undefined e e')
+    go (EApp _ (EApp _ (EApp _ (TBuiltin (TyArr _ _ (TyArr _ _ (TyArr _ (TyApp _ (TyB _ TyVec) _) _))) Fold) f) seed) xs) =
+        let f' = go f
+            seed' = go seed
+            xs' = asArr (go xs)
+        in foldE f' seed' xs'
+        where foldE op = V.foldl' (applyOp' op)
+              applyOp' op e e' = go (EApp undefined (EApp undefined op e) e')
+    go (Arr ty es) = Arr ty (go <$> es)
 
 applyOp :: Int
         -> E (T K) -- ^ Operator
@@ -274,7 +308,7 @@
 ir re i (EApp _ (EApp _ (BBuiltin _ Map) op) stream) = let op' = compileR op in fmap (applyUn i op') . ir re i stream
 ir re i (EApp _ (EApp _ (BBuiltin _ Filter) op) stream) =
     let op' = compileR op
-        in filter (\e -> asBool (eClosed i $ applyUn i op' e)) . ir re i stream
+        in filter (asBool . applyUn i op') . ir re i stream
 ir re i (EApp _ (EApp _ (BBuiltin _ Prior) op) stream) = prior (applyOp i op) . ir re i stream
 ir re i (EApp _ (EApp _ (EApp _ (TBuiltin _ ZipW) op) streaml) streamr) = \lineStream ->
     let
@@ -304,7 +338,7 @@
 
 -- evaluate something that has a fold nested in it
 eWith :: RurePtr -> Int -> E (T K) -> [BS.ByteString] -> E (T K)
-eWith re i (EApp _ (EApp _ (EApp _ (TBuiltin _ Fold) op) seed) stream) = foldWithCtx re i op seed stream -- FIXME: only fold on streams!!
+eWith re i (EApp _ (EApp _ (EApp _ (TBuiltin (TyArr _ _ (TyArr _ _ (TyArr _ (TyApp _ (TyB _ TyStream) _) _))) Fold) op) seed) stream) = foldWithCtx re i op seed stream
 eWith re i (EApp ty e0 e1)                                             = \bs -> eClosed i (EApp ty (eWith re i e0 bs) (eWith re i e1 bs))
 eWith _ _ e@BBuiltin{}                                                 = const e
 eWith _ _ e@UBuiltin{}                                                 = const e
@@ -325,7 +359,7 @@
               -> Either StreamError ([BS.ByteString] -> IO ())
 fileProcessor _ _ AllField{}    = Left NakedField
 fileProcessor _ _ Field{}       = Left NakedField
-fileProcessor _ _ Ix{}          = Left NakedField
+fileProcessor _ _ (NBuiltin _ Ix) = Left NakedField
 fileProcessor _ _ AllColumn{} = Right $ \inp ->
     printStream $ fmap mkStr inp
 fileProcessor re _ (Column _ i) = Right $ \inp -> do
@@ -341,7 +375,7 @@
     printStream $ ir re i e inp
 fileProcessor re i e@(EApp _ (EApp _ (BBuiltin _ Filter) _) _) = Right $ \inp -> do
     printStream $ ir re i e inp
-fileProcessor re i e@(EApp _ (EApp _ (BBuiltin _ Map) _) _) = Right $ \inp -> do
+fileProcessor re i e@(EApp _ (EApp _ (BBuiltin (TyArr _ _ (TyArr _ _ (TyApp _ (TyB _ TyStream) _))) Map) _) _) = Right $ \inp -> do
     printStream $ ir re i e inp
 fileProcessor re i e@(EApp _ (EApp _ (BBuiltin _ Prior) _) _) = Right $ \inp -> do
     printStream $ ir re i e inp
diff --git a/src/Jacinda/File.hs b/src/Jacinda/File.hs
--- a/src/Jacinda/File.hs
+++ b/src/Jacinda/File.hs
@@ -36,7 +36,7 @@
         Left err -> throw err
         Right (ast, m) ->
             let (typed, i) = yeet $ runTypeM m (tyProgram ast)
-            in closedProgram i typed
+            in closedProgram i (compileIn typed)
 
 compileFS :: Maybe BS.ByteString -> RurePtr
 compileFS (Just bs) = compileDefault bs
@@ -52,7 +52,8 @@
         Right (ast, m) -> do
             (typed, i) <- yeetIO $ runTypeM m (tyProgram ast)
             cont <- yeetIO $ runJac (compileFS (cliFS <|> getFS ast)) i typed
-            cont $ concatMap BSL.toChunks (ASCIIL.lines contents) -- FIXME: "lines" discards empty... perhaps ok?
+            cont $ fmap BSL.toStrict (ASCIIL.lines contents)
+            -- see: BSL.split, BSL.splitWith
 
 runOnHandle :: BSL.ByteString -- ^ Program
             -> Maybe BS.ByteString -- ^ Field separator
diff --git a/src/Jacinda/Lexer.x b/src/Jacinda/Lexer.x
--- a/src/Jacinda/Lexer.x
+++ b/src/Jacinda/Lexer.x
@@ -6,7 +6,6 @@
                          , runAlex
                          , runAlexSt
                          , withAlexSt
-                         , lexJac
                          , freshName
                          , AlexPosn (..)
                          , Alex (..)
@@ -20,6 +19,7 @@
 
 import Control.Arrow ((&&&))
 import Data.Bifunctor (first)
+import qualified Data.ByteString as BS
 import qualified Data.ByteString.Lazy as BSL
 import qualified Data.ByteString.Lazy.Char8 as ASCII
 import Data.Functor (($>))
@@ -27,7 +27,7 @@
 import qualified Data.Map as M
 import Data.Semigroup ((<>))
 import qualified Data.Text as T
-import Data.Text.Encoding (decodeUtf8)
+import Data.Text.Encoding (decodeUtf8, encodeUtf8)
 import Intern.Name
 import Intern.Unique
 import Prettyprinter (Pretty (pretty), (<+>), colon, squotes)
@@ -42,6 +42,12 @@
 
 @follow_char = [$latin $digit \_]
 
+$str_special = [\\\']
+
+@escape_str = \\ [$str_special n]
+
+@string = \' ([^ $str_special] | @escape_str)* \'
+
 @name = [a-z] @follow_char*
 @tyname = [A-Z] @follow_char*
 
@@ -54,6 +60,8 @@
         y                        { mkRes VarY }
     }
 
+    <0> "["                      { mkSym LSqBracket `andBegin` dfn } -- FIXME: this doesn't allow nested
+
     <0,dfn> {
 
         $white+                  ;
@@ -90,8 +98,7 @@
         ")"                      { mkSym RParen }
         "{%"                     { mkSym LBracePercent }
         "{|"                     { mkSym LBraceBar }
-        "["                      { mkSym LSqBracket `andBegin` dfn }
-        "]"                      { mkSym RSqBracket `andBegin` 0 } -- FIXME: this doesn't allow nested
+        "]"                      { mkSym RSqBracket `andBegin` 0 }
         "~"                      { mkSym Tilde }
         "!~"                     { mkSym NotMatchTok }
         ","                      { mkSym Comma }
@@ -106,7 +113,7 @@
 
         in                       { mkKw KwIn }
         let                      { mkKw KwLet }
-        val                      { mkKw KwVal }   
+        val                      { mkKw KwVal }
         end                      { mkKw KwEnd }
         :set                     { mkKw KwSet }
         fn                       { mkKw KwFn }
@@ -119,20 +126,24 @@
 
         substr                   { mkBuiltin BuiltinSubstr }
         split                    { mkBuiltin BuiltinSplit }
+        splitc                   { mkBuiltin BuiltinSplitc }
         sprintf                  { mkBuiltin BuiltinSprintf }
+        option                   { mkBuiltin BuiltinOption }
         floor                    { mkBuiltin BuiltinFloor }
         ceil                     { mkBuiltin BuiltinCeil }
+        match                    { mkBuiltin BuiltinMatch }
 
         ":i"                     { mkBuiltin BuiltinIParse }
         ":f"                     { mkBuiltin BuiltinFParse }
 
         "#t"                     { tok (\p _ -> alex $ TokBool p True) }
         "#f"                     { tok (\p _ -> alex $ TokBool p False) }
-    
+
         \$$digit+                { tok (\p s -> alex $ TokStreamLit p (read $ ASCII.unpack $ BSL.tail s)) }
         `$digit+                 { tok (\p s -> alex $ TokFieldLit p (read $ ASCII.unpack $ BSL.tail s)) }
 
         "."$digit+               { tok (\p s -> alex $ TokAccess p (read $ ASCII.unpack $ ASCII.tail s)) }
+        "->"$digit+              { tok (\p s -> alex $ TokSelect p (read $ ASCII.unpack $ ASCII.drop 2 s)) }
         $digit+                  { tok (\p s -> alex $ TokInt p (read $ ASCII.unpack s)) }
         _$digit+                 { tok (\p s -> alex $ TokInt p (negate $ read $ ASCII.unpack $ BSL.tail s)) }
 
@@ -141,7 +152,7 @@
 
         -- TODO: allow chars to be escaped
         -- TODO: consider dropping this syntax for strings?
-        '[^']*'                  { tok (\p s -> alex $ TokStr p (BSL.init $ BSL.tail s)) }
+        @string                  { tok (\p s -> alex $ TokStr p (escReplace' $ BSL.init $ BSL.tail s)) }
 
         "/"[^\/]*"/"             { tok (\p s -> alex $ TokRR p (BSL.init $ BSL.tail s)) } -- TODO: allow slashes that are escaped
 
@@ -170,6 +181,16 @@
 
 mkBuiltin = constructor TokBuiltin
 
+escReplace' :: BSL.ByteString -> BS.ByteString
+escReplace' = encodeUtf8 . escReplace . decodeUtf8 . BSL.toStrict
+
+-- this is inefficient but w/e
+escReplace :: T.Text -> T.Text
+escReplace =
+      T.replace "\\\"" "\""
+    . T.replace "\\n" "\n"
+    . T.replace "\\$" "$"
+
 mkText :: BSL.ByteString -> T.Text
 mkText = decodeUtf8 . BSL.toStrict
 
@@ -312,18 +333,24 @@
              | BuiltinFParse
              | BuiltinSubstr
              | BuiltinSplit
+             | BuiltinSplitc
+             | BuiltinOption
              | BuiltinSprintf
              | BuiltinFloor
              | BuiltinCeil
+             | BuiltinMatch
 
 instance Pretty Builtin where
     pretty BuiltinIParse  = ":i"
     pretty BuiltinFParse  = ":f"
     pretty BuiltinSubstr  = "substr"
     pretty BuiltinSplit   = "split"
+    pretty BuiltinOption  = "option"
+    pretty BuiltinSplitc  = "splitc"
     pretty BuiltinSprintf = "sprintf"
     pretty BuiltinFloor   = "floor"
     pretty BuiltinCeil    = "ceil"
+    pretty BuiltinMatch   = "match"
 
 data Token a = EOF { loc :: a }
              | TokSym { loc :: a, _sym :: Sym }
@@ -335,11 +362,12 @@
              | TokInt { loc :: a, int :: Integer }
              | TokFloat { loc :: a, float :: Double }
              | TokBool { loc :: a, boolTok :: Bool }
-             | TokStr { loc :: a, strTok :: BSL.ByteString }
+             | TokStr { loc :: a, strTok :: BS.ByteString }
              | TokStreamLit { loc :: a, ix :: Int }
              | TokFieldLit { loc :: a, ix :: Int }
              | TokRR { loc :: a, rr :: BSL.ByteString }
              | TokAccess { loc :: a, ix :: Int }
+             | TokSelect { loc :: a, field :: Int }
 
 instance Pretty (Token a) where
     pretty EOF{}              = "(eof)"
@@ -349,7 +377,7 @@
     pretty (TokBuiltin _ b)   = "builtin" <+> squotes (pretty b)
     pretty (TokKeyword _ kw)  = "keyword" <+> squotes (pretty kw)
     pretty (TokInt _ i)       = pretty i
-    pretty (TokStr _ str)     = squotes (pretty $ mkText str)
+    pretty (TokStr _ str)     = squotes (pretty $ decodeUtf8 str)
     pretty (TokStreamLit _ i) = "$" <> pretty i
     pretty (TokFieldLit _ i)  = "`" <> pretty i
     pretty (TokRR _ rr')      = "/" <> pretty (mkText rr') <> "/"
@@ -358,11 +386,12 @@
     pretty (TokBool _ False)  = "#f"
     pretty (TokAccess _ i)    = "." <> pretty i
     pretty (TokFloat _ f)     = pretty f
+    pretty (TokSelect _ i)    = "->" <> pretty i
 
 freshName :: T.Text -> Alex (Name AlexPosn)
 freshName t = do
     pos <- get_pos
-    newIdentAlex pos t 
+    newIdentAlex pos t
 
 newIdentAlex :: AlexPosn -> T.Text -> Alex (Name AlexPosn)
 newIdentAlex pos t = do
@@ -377,16 +406,6 @@
         Nothing -> let i = max' + 1
             in let newName = Name t (Unique i) pos
                 in ((i, M.insert t i names, IM.insert i newName uniqs), newName)
-
-loop :: Alex [Token AlexPosn]
-loop = do
-    tok' <- alexMonadScan
-    case tok' of
-        EOF{} -> pure []
-        _ -> (tok' :) <$> loop
-
-lexJac :: BSL.ByteString -> Either String [Token AlexPosn]
-lexJac = flip runAlex loop
 
 runAlexSt :: BSL.ByteString -> Alex a -> Either String (AlexUserState, a)
 runAlexSt inp = withAlexSt inp alexInitUserState
diff --git a/src/Jacinda/Parser.y b/src/Jacinda/Parser.y
--- a/src/Jacinda/Parser.y
+++ b/src/Jacinda/Parser.y
@@ -51,6 +51,7 @@
     exclamation { TokSym $$ Exclamation }
     backslashdot { TokSym $$ BackslashDot }
     at { $$@(TokAccess _ _) }
+    select { $$@(TokSelect _ _) }
 
     plus { TokSym $$ PlusTok }
     minus { TokSym $$ MinusTok }
@@ -100,10 +101,13 @@
     fs { TokResVar $$ VarFs }
 
     split { TokBuiltin $$ BuiltinSplit }
+    splitc { TokBuiltin $$ BuiltinSplitc }
     substr { TokBuiltin $$ BuiltinSubstr }
     sprintf { TokBuiltin $$ BuiltinSprintf }
     floor { TokBuiltin $$ BuiltinFloor }
     ceil { TokBuiltin $$ BuiltinCeil }
+    option { TokBuiltin $$ BuiltinOption }
+    match { TokBuiltin $$ BuiltinMatch }
 
     iParse { TokBuiltin $$ BuiltinIParse }
     fParse { TokBuiltin $$ BuiltinFParse }
@@ -173,7 +177,7 @@
   | intLit { IntLit (loc $1) (int $1) }
   | floatLit { FloatLit (loc $1) (float $1) }
   | boolLit { BoolLit (loc $1) (boolTok $1) }
-  | strLit { StrLit (loc $1) (BSL.toStrict $ strTok $1) }
+  | strLit { StrLit (loc $1) (strTok $1) }
   | column { Column (loc $1) (ix $1) }
   | field { Field (loc $1) (ix $1) }
   | allColumn { AllColumn $1 }
@@ -211,13 +215,18 @@
   | min { BBuiltin $1 Min }
   | max { BBuiltin $1 Max }
   | split { BBuiltin $1 Split }
+  | match { BBuiltin $1 Match }
+  | splitc { BBuiltin $1 Splitc }
   | substr { TBuiltin $1 Substr }
   | sprintf { BBuiltin $1 Sprintf }
+  | option { TBuiltin $1 Option }
   | floor { UBuiltin $1 Floor }
   | ceil { UBuiltin $1 Ceiling }
-  | ix { Ix $1 }
+  | ix { NBuiltin $1 Ix }
   | parens(at) { UBuiltin (loc $1) (At $ ix $1) }
+  | parens(select) { UBuiltin (loc $1) (Select $ field $1) }
   | E at { EApp (eLoc $1) (UBuiltin (loc $2) (At $ ix $2)) $1 }
+  | E select { EApp (eLoc $1) (UBuiltin (loc $2) (Select $ field $2)) $1 }
   | backslash name dot E { Lam $1 $2 $4 }
   | parens(E) { Paren (eLoc $1) $1 }
 
diff --git a/src/Jacinda/Parser/Rewrite.hs b/src/Jacinda/Parser/Rewrite.hs
--- a/src/Jacinda/Parser/Rewrite.hs
+++ b/src/Jacinda/Parser/Rewrite.hs
@@ -35,7 +35,11 @@
     a (EAppF l e0@(BBuiltin _ Max) (EApp lϵ e1 e2))                                                 = EApp l (EApp lϵ e0 e1) e2
     a (EAppF l e0@(BBuiltin _ Min) (EApp lϵ e1 e2))                                                 = EApp l (EApp lϵ e0 e1) e2
     a (EAppF l e0@(BBuiltin _ Split) (EApp lϵ e1 e2))                                               = EApp l (EApp lϵ e0 e1) e2
+    a (EAppF l e0@(BBuiltin _ Match) (EApp lϵ e1 e2))                                               = EApp l (EApp lϵ e0 e1) e2
+    a (EAppF l e0@(BBuiltin _ Splitc) (EApp lϵ e1 e2))                                              = EApp l (EApp lϵ e0 e1) e2
     a (EAppF l e0@(BBuiltin _ Sprintf) (EApp lϵ e1 e2))                                             = EApp l (EApp lϵ e0 e1) e2
     a (EAppF l e0@(TBuiltin _ Substr) (EApp lϵ (EApp lϵϵ e1 e2) e3))                                = EApp l (EApp lϵ (EApp lϵϵ e0 e1) e2) e3
     a (EAppF l e0@(TBuiltin _ Substr) (EApp lϵ e1 (EApp lϵϵ e2 e3)))                                = EApp l (EApp lϵ (EApp lϵϵ e0 e1) e2) e3
+    a (EAppF l e0@(TBuiltin _ Option) (EApp lϵ (EApp lϵϵ e1 e2) e3))                                = EApp l (EApp lϵ (EApp lϵϵ e0 e1) e2) e3
+    a (EAppF l e0@(TBuiltin _ Option) (EApp lϵ e1 (EApp lϵϵ e2 e3)))                                = EApp l (EApp lϵ (EApp lϵϵ e0 e1) e2) e3
     a x                                                                                             = embed x
diff --git a/src/Jacinda/Regex.hs b/src/Jacinda/Regex.hs
--- a/src/Jacinda/Regex.hs
+++ b/src/Jacinda/Regex.hs
@@ -5,6 +5,7 @@
                      , splitWhitespace
                      , defaultRurePtr
                      , isMatch'
+                     , find'
                      , compileDefault
                      , substr
                      ) where
@@ -15,7 +16,7 @@
 import           Data.Semigroup           ((<>))
 import qualified Data.Vector              as V
 import           Foreign.ForeignPtr       (plusForeignPtr)
-import           Regex.Rure               (RureMatch (..), RurePtr, compile, isMatch, matches, mkIter, rureDefaultFlags, rureFlagDotNL)
+import           Regex.Rure               (RureMatch (..), RurePtr, compile, find, isMatch, matches, mkIter, rureDefaultFlags, rureFlagDotNL)
 import           System.IO.Unsafe         (unsafeDupablePerformIO, unsafePerformIO)
 
 -- see: https://docs.rs/regex/latest/regex/#perl-character-classes-unicode-friendly
@@ -33,8 +34,12 @@
 splitWhitespace = splitBy defaultRurePtr
 
 substr :: BS.ByteString -> Int -> Int -> BS.ByteString
-substr (BS.BS fp l) begin endϵ | endϵ >= begin = BS.BS (fp `plusForeignPtr` begin) ((min l endϵ)-begin)
+substr (BS.BS fp l) begin endϵ | endϵ >= begin = BS.BS (fp `plusForeignPtr` begin) (min l endϵ - begin)
                                | otherwise = "error: invalid substring indices."
+
+{-# NOINLINE find' #-}
+find' :: RurePtr -> BS.ByteString -> Maybe RureMatch
+find' re str = unsafeDupablePerformIO $ find re str 0
 
 {-# NOINLINE splitBy #-}
 splitBy :: RurePtr
diff --git a/src/Jacinda/Rename.hs b/src/Jacinda/Rename.hs
--- a/src/Jacinda/Rename.hs
+++ b/src/Jacinda/Rename.hs
@@ -101,6 +101,8 @@
     a DfnF{}           = error "Not supported yet."
     a (LetF _ b e)     = e || snd b
     a (GuardedF _ p b) = b || p
+    a (ImplicitF _ e)  = e
+    a (ParenF _ e)     = e
     a _                = False
 
 replaceXY :: (a -> Name a) -- ^ @x@
@@ -147,4 +149,6 @@
     (n', modR) <- withName n
     Let l (n', eϵ') <$> withRenames modR (renameE e')
 renameE (Paren _ e) = renameE e
+renameE (Arr l es) = Arr l <$> traverse renameE es
+renameE (OptionVal l e) = OptionVal l <$> traverse renameE e
 renameE e = pure e -- literals &c.
diff --git a/src/Jacinda/Ty.hs b/src/Jacinda/Ty.hs
--- a/src/Jacinda/Ty.hs
+++ b/src/Jacinda/Ty.hs
@@ -11,7 +11,7 @@
 import           Control.Exception          (Exception)
 import           Control.Monad.Except       (throwError)
 import           Control.Monad.State.Strict (StateT, gets, runStateT)
-import           Data.Bifunctor             (second)
+import           Data.Bifunctor             (first, second)
 import           Data.Foldable              (traverse_)
 import           Data.Functor               (void, ($>))
 import qualified Data.IntMap                as IM
@@ -20,6 +20,7 @@
 import qualified Data.Set                   as S
 import qualified Data.Text                  as T
 import           Data.Typeable              (Typeable)
+import           Debug.Trace
 import           Intern.Name
 import           Intern.Unique
 import           Jacinda.AST
@@ -34,12 +35,12 @@
 (<#>) x y = x <> hardline <> y
 
 data Error a = UnificationFailed a (T ()) (T ())
-             | Doesn'tSatisfy (T ()) C
+             | Doesn'tSatisfy a (T ()) C
              | IllScoped a (Name a)
 
 instance Pretty a => Pretty (Error a) where
     pretty (UnificationFailed l ty ty') = pretty l <+> "could not unify type" <+> squotes (pretty ty) <+> "with" <+> squotes (pretty ty')
-    pretty (Doesn'tSatisfy ty c)        = squotes (pretty ty) <+> "is not a member of class" <+> pretty c
+    pretty (Doesn'tSatisfy l ty c)      = pretty l <+> squotes (pretty ty) <+> "is not a member of class" <+> pretty c
     pretty (IllScoped l n)              = pretty l <+> squotes (pretty n) <+> "is not in scope."
 
 instance Pretty a => Show (Error a) where
@@ -51,7 +52,7 @@
 -- (after accumulating classVar membership...)
 data TyState a = TyState { maxU        :: Int
                          , kindEnv     :: IM.IntMap K
-                         , classVars   :: IM.IntMap (S.Set C)
+                         , classVars   :: IM.IntMap (S.Set (C, a))
                          , varEnv      :: IM.IntMap (T K)
                          , constraints :: S.Set (a, T K, T K)
                          }
@@ -70,7 +71,7 @@
 maxULens :: Lens' (TyState a) Int
 maxULens f s = fmap (\x -> s { maxU = x }) (f (maxU s))
 
-classVarsLens :: Lens' (TyState a) (IM.IntMap (S.Set C))
+classVarsLens :: Lens' (TyState a) (IM.IntMap (S.Set (C, a)))
 classVarsLens f s = fmap (\x -> s { classVars = x }) (f (classVars s))
 
 varEnvLens :: Lens' (TyState a) (IM.IntMap (T K))
@@ -123,6 +124,9 @@
 unifyMatch um ((_, TyVar _ (Name _ (Unique k) _), ty@(TyApp{})):tys) = IM.insert k ty <$> unifyPrep (IM.insert k ty um) tys
 unifyMatch um ((l, TyApp _ ty ty', TyApp _ ty'' ty'''):tys) = unifyPrep um ((l, ty, ty'') : (l, ty', ty''') : tys)
 unifyMatch um ((l, TyArr _ ty ty', TyArr _ ty'' ty'''):tys) = unifyPrep um ((l, ty, ty'') : (l, ty', ty''') : tys)
+unifyMatch um ((l, ty@(TyTup _ tys), ty'@(TyTup _ tys')):tyss)
+    | length tys == length tys' = unifyPrep um (zip3 (repeat l) tys tys' ++ tyss)
+    | otherwise = throwError (UnificationFailed l (void ty) (void ty'))
 unifyMatch um ((_, TyVar _ n@(Name _ (Unique k) _), ty@(TyVar _ n')):tys)
     | n == n' = unifyPrep um tys -- a type variable is always equal to itself, don't bother inserting this!
     | otherwise = IM.insert k ty <$> unifyPrep (IM.insert k ty um) tys
@@ -166,7 +170,7 @@
 dummyName :: T.Text -> TypeM a (Name K)
 dummyName n = freshName n Star
 
-addC :: Name a -> C -> IM.IntMap (S.Set C) -> IM.IntMap (S.Set C)
+addC :: Ord a => Name b -> (C, a) -> IM.IntMap (S.Set (C, a)) -> IM.IntMap (S.Set (C, a))
 addC (Name _ (Unique i) _) c = IM.alter (Just . go) i where
     go Nothing   = S.singleton c
     go (Just cs) = S.insert c cs
@@ -184,48 +188,58 @@
     modifying constraintsLens (S.insert (l, ty, ty'))
 
 -- TODO: this will need some class context if we permit custom types (Optional)
-checkType :: T b -> C -> TypeM a ()
-checkType TyVar{} _                       = pure () -- TODO: I think this is right
-checkType (TyB _ TyStr) IsSemigroup       = pure ()
-checkType (TyB _ TyInteger) IsSemigroup   = pure ()
-checkType (TyB _ TyInteger) IsNum         = pure ()
-checkType (TyB _ TyInteger) IsOrd         = pure ()
-checkType (TyB _ TyInteger) IsEq          = pure ()
-checkType (TyB _ TyInteger) IsParseable   = pure ()
-checkType (TyB _ TyFloat) IsParseable     = pure ()
-checkType (TyB _ TyFloat) IsSemigroup     = pure ()
-checkType (TyB _ TyFloat) IsNum           = pure ()
-checkType (TyB _ TyFloat) IsOrd           = pure ()
-checkType (TyB _ TyFloat) IsEq            = pure ()
-checkType (TyB _ TyBool) IsEq             = pure ()
-checkType (TyB _ TyStr) IsEq              = pure ()
-checkType (TyTup _ tys) IsEq              = traverse_ (`checkType` IsEq) tys
-checkType (TyTup _ tys) IsOrd             = traverse_ (`checkType` IsOrd) tys
-checkType (TyApp _ (TyB _ TyVec) ty) IsEq = checkType ty IsEq
-checkType ty@TyTup{} c@IsNum              = throwError $ Doesn'tSatisfy (void ty) c
-checkType ty@(TyB _ TyStr) c@IsNum        = throwError $ Doesn'tSatisfy (void ty) c
-checkType ty@(TyB _ TyBool) c@IsNum       = throwError $ Doesn'tSatisfy (void ty) c
-checkType ty@TyArr{} c                    = throwError $ Doesn'tSatisfy (void ty) c
-checkType (TyB _ TyVec) Functor           = pure ()
-checkType (TyB _ TyStream) Functor        = pure ()
-checkType ty c@Functor                    = throwError $ Doesn'tSatisfy (void ty) c
-checkType (TyB _ TyVec) Foldable          = pure ()
-checkType (TyB _ TyStream) Foldable       = pure ()
-checkType ty c@Foldable                   = throwError $ Doesn'tSatisfy (void ty) c
-checkType (TyB _ TyStr) IsPrintf          = pure ()
-checkType (TyB _ TyFloat) IsPrintf        = pure ()
-checkType (TyB _ TyInteger) IsPrintf      = pure ()
-checkType (TyB _ TyBool) IsPrintf         = pure ()
-checkType (TyTup _ tys) IsPrintf          = traverse_ (`checkType` IsPrintf) tys
-checkType ty c@IsPrintf                   = throwError $ Doesn'tSatisfy (void ty) c
+checkType :: Ord a => T K -> (C, a) -> TypeM a ()
+checkType TyVar{} _                            = pure () -- TODO: I think this is right
+checkType (TyB _ TyStr) (IsSemigroup, _)       = pure ()
+checkType (TyB _ TyInteger) (IsSemigroup, _)   = pure ()
+checkType (TyB _ TyInteger) (IsNum, _)         = pure ()
+checkType (TyB _ TyInteger) (IsOrd, _)         = pure ()
+checkType (TyB _ TyInteger) (IsEq, _)          = pure ()
+checkType (TyB _ TyInteger) (IsParseable, _)   = pure ()
+checkType (TyB _ TyFloat) (IsParseable, _)     = pure ()
+checkType (TyB _ TyFloat) (IsSemigroup, _)     = pure ()
+checkType (TyB _ TyFloat) (IsNum, _)           = pure ()
+checkType (TyB _ TyFloat) (IsOrd, _)           = pure ()
+checkType (TyB _ TyFloat) (IsEq, _)            = pure ()
+checkType (TyB _ TyBool) (IsEq, _)             = pure ()
+checkType (TyB _ TyStr) (IsEq, _)              = pure ()
+checkType (TyTup _ tys) (IsEq, l)              = traverse_ (`checkType` (IsEq, l)) tys
+checkType (TyTup _ tys) (IsOrd, l)             = traverse_ (`checkType` (IsOrd, l)) tys
+checkType (TyApp _ (TyB _ TyVec) ty) (IsEq, l) = checkType ty (IsEq, l)
+checkType ty@TyTup{} (c@IsNum, l)              = throwError $ Doesn'tSatisfy l (void ty) c
+checkType ty@(TyB _ TyStr) (c@IsNum, l)        = throwError $ Doesn'tSatisfy l (void ty) c
+checkType ty@(TyB _ TyBool) (c@IsNum, l)       = throwError $ Doesn'tSatisfy l (void ty) c
+checkType ty@TyArr{} (c, l)                    = throwError $ Doesn'tSatisfy l (void ty) c
+checkType (TyB _ TyVec) (Functor, _)           = pure ()
+checkType (TyB _ TyStream) (Functor, _)        = pure ()
+checkType ty (c@Functor, l)                    = throwError $ Doesn'tSatisfy l (void ty) c
+checkType (TyB _ TyVec) (Foldable, _)          = pure ()
+checkType (TyB _ TyStream) (Foldable, _)       = pure ()
+checkType ty (c@Foldable, l)                   = throwError $ Doesn'tSatisfy l (void ty) c
+checkType (TyB _ TyStr) (IsPrintf, _)          = pure ()
+checkType (TyB _ TyFloat) (IsPrintf, _)        = pure ()
+checkType (TyB _ TyInteger) (IsPrintf, _)      = pure ()
+checkType (TyB _ TyBool) (IsPrintf, _)         = pure ()
+checkType (TyTup _ tys) (IsPrintf, l)          = traverse_ (`checkType` (IsPrintf, l)) tys
+checkType ty (c@IsPrintf, l)                   = throwError $ Doesn'tSatisfy l (void ty) c
+checkType ty@(TyTup _ tys) (c@(HasField i ty'), l) | length tys >= i = pushConstraint l ty' (tys !! (i-1))
+                                                   | otherwise = throwError $ Doesn'tSatisfy l (void ty) c
+checkType ty (c@HasField{}, l)                 = throwError $ Doesn'tSatisfy l (void ty) c
 
-checkClass :: IM.IntMap (T K) -- ^ Unification result
+substC :: IM.IntMap (T K) -- ^ Unification result
+       -> C
+       -> C
+substC um (HasField i ty) = HasField i (substConstraints um ty)
+substC _ c                = c
+
+checkClass :: Ord a
+           => IM.IntMap (T K) -- ^ Unification result
            -> Int
-           -> S.Set C
+           -> S.Set (C, a)
            -> TypeM a ()
 checkClass tys i cs =
     case substInt tys i of
-        Just ty -> traverse_ (checkType ty) (S.toList cs)
+        Just ty -> traverse_ (checkType ty) (first (substC tys) <$> S.toList cs)
         Nothing -> pure () -- FIXME: do we need to check var is well-kinded for constraint?
 
 lookupVar :: Name a -> TypeM a (T K)
@@ -254,7 +268,9 @@
     backNames <- unifyM =<< gets constraints
     toCheck <- gets (IM.toList . classVars)
     traverse_ (uncurry (checkClass backNames)) toCheck
-    pure (fmap (substConstraints backNames) (Program ds' e'))
+    backNames' <- unifyM =<< gets constraints
+    -- FIXME: not sure if termination/whatever is guaranteed, need 2 think..
+    pure (fmap (substConstraints backNames') (Program ds' e'))
 
 -- FIXME kind check
 tyE :: Ord a => E a -> TypeM a (E (T K))
@@ -265,39 +281,39 @@
     traverse_ (uncurry (checkClass backNames)) toCheck
     pure (fmap (substConstraints backNames) e')
 
-tyNumOp :: TypeM a (T K)
-tyNumOp = do
+tyNumOp :: Ord a => a -> TypeM a (T K)
+tyNumOp l = do
     m <- dummyName "m"
-    modifying classVarsLens (addC m IsNum)
+    modifying classVarsLens (addC m (IsNum, l))
     let m' = var m
     pure $ tyArr m' (tyArr m' m')
 
-tySemiOp :: TypeM a (T K)
-tySemiOp = do
+tySemiOp :: Ord a => a -> TypeM a (T K)
+tySemiOp l = do
     m <- dummyName "m"
-    modifying classVarsLens (addC m IsSemigroup)
+    modifying classVarsLens (addC m (IsSemigroup, l))
     let m' = var m
     pure $ tyArr m' (tyArr m' m')
 
-tyOrd :: TypeM a (T K)
-tyOrd = do
+tyOrd :: Ord a => a -> TypeM a (T K)
+tyOrd l = do
     a <- dummyName "a"
-    modifying classVarsLens (addC a IsOrd)
+    modifying classVarsLens (addC a (IsOrd, l))
     let a' = var a
     pure $ tyArr a' (tyArr a' tyBool)
 
-tyEq :: TypeM a (T K)
-tyEq = do
+tyEq :: Ord a => a -> TypeM a (T K)
+tyEq l = do
     a <- dummyName "a"
-    modifying classVarsLens (addC a IsEq)
+    modifying classVarsLens (addC a (IsEq, l))
     let a' = var a
     pure $ tyArr a' (tyArr a' tyBool)
 
 -- min/max
-tyM :: TypeM a (T K)
-tyM = do
+tyM :: Ord a => a -> TypeM a (T K)
+tyM l = do
     a <- dummyName "a"
-    modifying classVarsLens (addC a IsOrd)
+    modifying classVarsLens (addC a (IsOrd, l))
     let a' = var a
     pure $ tyArr a' (tyArr a' a')
 
@@ -310,6 +326,9 @@
 tyVec :: T K
 tyVec = TyB (KArr Star Star) TyVec
 
+tyOpt :: T K -> T K
+tyOpt = hkt (TyB (KArr Star Star) TyOption)
+
 tyE0 :: Ord a => E a -> TypeM a (E (T K))
 tyE0 (BoolLit _ b)           = pure $ BoolLit tyBool b
 tyE0 (IntLit _ i)            = pure $ IntLit tyI i
@@ -322,19 +341,20 @@
 tyE0 (Field _ i)             = pure $ Field tyStr i
 tyE0 AllField{}              = pure $ AllField tyStr
 tyE0 AllColumn{}             = pure $ AllColumn (tyStream tyStr)
-tyE0 Ix{}                    = pure $ Ix tyI
-tyE0 (BBuiltin _ Plus)       = BBuiltin <$> tySemiOp <*> pure Plus
-tyE0 (BBuiltin _ Minus)      = BBuiltin <$> tyNumOp <*> pure Minus
-tyE0 (BBuiltin _ Times)      = BBuiltin <$> tyNumOp <*> pure Times
-tyE0 (BBuiltin _ Gt)         = BBuiltin <$> tyOrd <*> pure Gt
-tyE0 (BBuiltin _ Lt)         = BBuiltin <$> tyOrd <*> pure Lt
-tyE0 (BBuiltin _ Geq)        = BBuiltin <$> tyOrd <*> pure Geq
-tyE0 (BBuiltin _ Leq)        = BBuiltin <$> tyOrd <*> pure Leq
-tyE0 (BBuiltin _ Eq)         = BBuiltin <$> tyEq <*> pure Eq
-tyE0 (BBuiltin _ Neq)        = BBuiltin <$> tyEq <*> pure Neq
-tyE0 (BBuiltin _ Min)        = BBuiltin <$> tyM <*> pure Min
-tyE0 (BBuiltin _ Max)        = BBuiltin <$> tyM <*> pure Max
+tyE0 (NBuiltin _ Ix)         = pure $ NBuiltin tyI Ix
+tyE0 (BBuiltin l Plus)       = BBuiltin <$> tySemiOp l <*> pure Plus
+tyE0 (BBuiltin l Minus)      = BBuiltin <$> tyNumOp l <*> pure Minus
+tyE0 (BBuiltin l Times)      = BBuiltin <$> tyNumOp l <*> pure Times
+tyE0 (BBuiltin l Gt)         = BBuiltin <$> tyOrd l <*> pure Gt
+tyE0 (BBuiltin l Lt)         = BBuiltin <$> tyOrd l <*> pure Lt
+tyE0 (BBuiltin l Geq)        = BBuiltin <$> tyOrd l <*> pure Geq
+tyE0 (BBuiltin l Leq)        = BBuiltin <$> tyOrd l <*> pure Leq
+tyE0 (BBuiltin l Eq)         = BBuiltin <$> tyEq l <*> pure Eq
+tyE0 (BBuiltin l Neq)        = BBuiltin <$> tyEq l <*> pure Neq
+tyE0 (BBuiltin l Min)        = BBuiltin <$> tyM l <*> pure Min
+tyE0 (BBuiltin l Max)        = BBuiltin <$> tyM l <*> pure Max
 tyE0 (BBuiltin _ Split)      = pure $ BBuiltin (tyArr tyStr (tyArr tyStr (hkt tyVec tyStr))) Split
+tyE0 (BBuiltin _ Splitc)     = pure $ BBuiltin (tyArr tyStr (tyArr tyStr (hkt tyVec tyStr))) Splitc
 tyE0 (BBuiltin _ Matches)    = pure $ BBuiltin (tyArr tyStr (tyArr tyStr tyBool)) Matches
 tyE0 (BBuiltin _ NotMatches) = pure $ BBuiltin (tyArr tyStr (tyArr tyStr tyBool)) NotMatches
 tyE0 (UBuiltin _ Tally)      = pure $ UBuiltin (tyArr tyStr tyI) Tally
@@ -342,21 +362,29 @@
 tyE0 (UBuiltin _ Not)        = pure $ UBuiltin (tyArr tyBool tyBool) Not
 tyE0 (BBuiltin _ And)        = pure $ BBuiltin (tyArr tyBool (tyArr tyBool tyBool)) And
 tyE0 (BBuiltin _ Or)         = pure $ BBuiltin (tyArr tyBool (tyArr tyBool tyBool)) Or
+tyE0 (BBuiltin _ Match)      = pure $ BBuiltin (tyArr tyStr (tyArr tyStr (tyOpt $ TyTup Star [tyI, tyI]))) Match
 tyE0 (TBuiltin _ Substr)     = pure $ TBuiltin (tyArr tyStr (tyArr tyI (tyArr tyI tyStr))) Substr
 tyE0 (UBuiltin _ IParse)     = pure $ UBuiltin (tyArr tyStr tyI) IParse
 tyE0 (UBuiltin _ FParse)     = pure $ UBuiltin (tyArr tyStr tyF) FParse
 tyE0 (UBuiltin _ Floor)      = pure $ UBuiltin (tyArr tyF tyI) Floor
 tyE0 (UBuiltin _ Ceiling)    = pure $ UBuiltin (tyArr tyF tyI) Ceiling
-tyE0 (BBuiltin _ Sprintf) = do
+tyE0 (BBuiltin l Sprintf) = do
     a <- dummyName "a"
     let a' = var a
-    modifying classVarsLens (addC a IsPrintf)
+    modifying classVarsLens (addC a (IsPrintf, l))
     pure $ BBuiltin (tyArr tyStr (tyArr a' tyStr)) Sprintf
 tyE0 (UBuiltin _ (At i)) = do
     a <- dummyName "a"
     let a' = var a
         tyV = hkt tyVec a'
     pure $ UBuiltin (tyArr tyV a') (At i)
+tyE0 (UBuiltin l (Select i)) = do
+    a <- dummyName "a"
+    b <- dummyName "b"
+    let a' = var a
+        b' = var b
+    modifying classVarsLens (addC a (HasField i b', l))
+    pure $ UBuiltin (tyArr a' b') (Select i)
 tyE0 (UBuiltin _ Const) = do
     a <- dummyName "a"
     b <- dummyName "b"
@@ -369,7 +397,7 @@
     let a' = var a
         fTy = tyArr (tyArr a' tyBool) (tyArr (tyStream a') (tyStream a'))
     pure $ BBuiltin fTy Filter
-tyE0 (BBuiltin _ Map) = do
+tyE0 (BBuiltin l Map) = do
     a <- dummyName "a"
     b <- dummyName "b"
     f <- higherOrder "f"
@@ -377,10 +405,10 @@
         b' = var b
         f' = var f
         fTy = tyArr (tyArr a' b') (tyArr (hkt f' a') (hkt f' b'))
-    modifying classVarsLens (addC f Functor)
+    modifying classVarsLens (addC f (Functor, l))
     pure $ BBuiltin fTy Map
 -- (b -> a -> b) -> b -> Stream a -> b
-tyE0 (TBuiltin _ Fold) = do
+tyE0 (TBuiltin l Fold) = do
     b <- dummyName "b"
     a <- dummyName "a"
     f <- higherOrder "f"
@@ -388,7 +416,7 @@
         a' = var a
         f' = var f
         fTy = tyArr (tyArr b' (tyArr a' b')) (tyArr b' (tyArr (hkt f' a') b'))
-    modifying classVarsLens (addC f Foldable)
+    modifying classVarsLens (addC f (Foldable, l))
     pure $ TBuiltin fTy Fold
 -- (a -> a -> a) -> Stream a -> Stream a
 tyE0 (BBuiltin _ Prior) = do
@@ -414,6 +442,13 @@
         a' = var a
         fTy = tyArr (tyArr b' (tyArr a' b')) (tyArr b' (tyArr (tyStream a') (tyStream b')))
     pure $ TBuiltin fTy Scan
+tyE0 (TBuiltin _ Option) = do
+    b <- dummyName "b"
+    a <- dummyName "a"
+    let b' = var b
+        a' = var a
+        fTy = tyArr b' (tyArr (tyArr a' b') (tyArr (tyOpt a') b'))
+    pure $ TBuiltin fTy Option
 tyE0 (Implicit _ e) = do
     e' <- tyE0 e
     pure $ Implicit (tyStream (eLoc e')) e'
@@ -457,3 +492,10 @@
 tyE0 (ResVar _ Y) = desugar
 tyE0 RegexCompiled{} = error "Regex should not be compiled at this stage."
 tyE0 Paren{} = desugar
+tyE0 (OptionVal _ (Just e)) = do
+    e' <- tyE0 e
+    pure $ OptionVal (tyOpt $ eLoc e') (Just e')
+tyE0 (OptionVal _ Nothing) = do
+    a <- dummyName "a"
+    let a' = var a
+    pure $ OptionVal (tyOpt a') Nothing
diff --git a/test/examples/ab.jac b/test/examples/ab.jac
new file mode 100644
--- /dev/null
+++ b/test/examples/ab.jac
@@ -0,0 +1,5 @@
+let
+  val asec := {`2 ~ /^[aA][0-9]+/}{1}
+  val bsec := {`2 ~ /^[bB][0-9]+/}{1}
+  val sum := [(+)|0 x]
+in (sum asec . sum bsec) end
diff --git a/test/examples/awkBook1.jac b/test/examples/awkBook1.jac
new file mode 100644
--- /dev/null
+++ b/test/examples/awkBook1.jac
@@ -0,0 +1,2 @@
+{. TODO: maybe need parseable class?
+{`3:i>0}{(`1.`2:f*`3:f)}
diff --git a/test/examples/hadoop.jac b/test/examples/hadoop.jac
new file mode 100644
--- /dev/null
+++ b/test/examples/hadoop.jac
@@ -0,0 +1,13 @@
+{. cat *.pgn | grep "Result" | awk ...
+{. awk '{ split($0, a, "-"); res = substr(a[1], length(a[1]), 1); if (res == 1) white++; if (res == 0) black++; if (res == 2) draw++;} END { print white+black+draw, white, black, draw }'
+{. cat *.pgn | grep "Result" | awk '{ split($0, a, "-"); res = substr(a[1], length(a[1]), 1); print $0, a[1], res;}'
+
+{. N.B. should be easier? count records/columns
+{. awk '{games += $1; white += $2; black += $3; draw += $4; } END { print games, white, black, draw }'
+
+let
+  val l := [(+)|0 x]
+  val white := l {`1:i = 1}{1}
+  val black := l {`1:i = 0}{1}
+  val draw := l {`1:i = 2}{1}
+in (white + black + draw . white . black . draw) end
diff --git a/test/examples/line.jac b/test/examples/line.jac
new file mode 100644
--- /dev/null
+++ b/test/examples/line.jac
@@ -0,0 +1,2 @@
+{. print all lines > 72 bytes
+{#`0>72}{`0}
diff --git a/test/examples/pop.jac b/test/examples/pop.jac
new file mode 100644
--- /dev/null
+++ b/test/examples/pop.jac
@@ -0,0 +1,4 @@
+{. see test/examples/data/countries, awk book
+let
+  val popBy := [(+)|0 {% x}{`3:i}]
+in (popBy /Asia/ . popBy /Europe/) end
diff --git a/test/examples/ty.jac b/test/examples/ty.jac
new file mode 100644
--- /dev/null
+++ b/test/examples/ty.jac
@@ -0,0 +1,4 @@
+fn count(x) :=
+  (+)|0 [:1"x;
+
+1
