Implement FromField Bool

lib/Database/PostgreSQL/Opium/FromField.hs

@@ -85,3 +85,15 @@ instance FromField Double where
   fromField = fromParser
     (Oid.real \/ Oid.doublePrecision)
     floatParser
+
+boolParser :: Parser Bool
+boolParser = choice
+  [ string "t" $> True
+  , string "f" $> False
+  ]
+
+-- | See https://www.postgresql.org/docs/current/datatype-boolean.html.
+instance FromField Bool where
+  fromField = fromParser
+    Oid.boolean
+    boolParser

lib/Database/PostgreSQL/Opium/Oid.hs

@@ -39,3 +39,7 @@ real = eq $ Oid 700
 -- | 64-bit IEEE float
 doublePrecision :: Oid -> Bool
 doublePrecision = eq $ Oid 701
+
+-- | Boolean
+boolean :: Oid -> Bool
+boolean = eq $ Oid 16