Add a SQL quasi-quoter.

Database/MySQL/Simple/QQ.hs

@@ -0,0 +1,45 @@
+{-# LANGUAGE TemplateHaskell, TypeApplications #-}
+module Database.MySQL.Simple.QQ
+  ( sql
+  ) where
+
+import Prelude
+import Language.Haskell.TH          (Exp, Q, appE, stringE)
+import Language.Haskell.TH.Quote    (QuasiQuoter (..))
+import Database.MySQL.Simple        (Query, Query)
+import Text.Printf                  (printf)
+
+-- | A quasi-quoter for SQL expressions.
+--
+-- The quasi-quoter does not do any sort of parsing of the SQL.  It's
+-- simply a convenience for writing multi-line SQL statements.  So in stead of:
+--
+-- > query
+-- >   =  "select * "
+-- >   <> "from users "
+-- >   <> "where email is null;"
+--
+-- You could write
+--
+-- > query = [sql|
+-- >   select *
+-- >   from users
+-- >   where email is null;
+-- > |]
+--
+-- Note the quasi-quoter is only valid in expression contexts.
+--
+-- @since 0.4.7
+sql :: QuasiQuoter
+sql = QuasiQuoter
+  { quotePat  = err "pattern"
+  , quoteType = error "Database.MySQL.Simple.QQ.sql: quasiquoter used in type context"
+  , quoteDec  = error "Database.MySQL.Simple.QQ.sql: quasiquoter used in declaration context"
+  , quoteExp  = quote
+  }
+  where
+  err :: String -> a
+  err ctxt = error (printf "Database.MySQL.Simple.QQ.sql: quasiquoter used in %s context" ctxt)
+
+quote :: String -> Q Exp
+quote = appE [| fromString @Query |] . stringE

mysql-simple.cabal

@@ -1,5 +1,5 @@
 name:           mysql-simple
-version:        0.4.6
+version:        0.4.7
 homepage:       https://github.com/paul-rouse/mysql-simple
 bug-reports:    https://github.com/paul-rouse/mysql-simple/issues
 synopsis:       A mid-level MySQL client library.
@@ -36,6 +36,7 @@ library
   exposed-modules:
     Database.MySQL.Simple
     Database.MySQL.Simple.Param
+    Database.MySQL.Simple.QQ
     Database.MySQL.Simple.QueryParams
     Database.MySQL.Simple.QueryResults
     Database.MySQL.Simple.Result
@@ -57,7 +58,8 @@ library
     pcre-light,
     old-locale,
     text >= 0.11.0.2,
-    time
+    time,
+    template-haskell
   if !impl(ghc >= 8.0)
     build-depends:
       semigroups >= 0.11 && < 0.19