4cb7797 · rel8 · git.iko.soy

git.iko.soy/rel8

Rename where{,Not}Exists to present and absent respectively

commit4cb7797d9e41765f08a1f7477f45eeb63b89ce8b authorShane O'Brien <shane.obrien@circuithub.com> dateSat 19 Jun 2021, 11:46 (5 years ago) parentbac704c

4 files changed+28−20

compare with master

unifiedsplit

Changelog.md+8 docs/concepts/queries.rst+6−6 src/Rel8.hs+2−2 src/Rel8/Query/Exists.hs+12−12

Changelog.md+8

@@ -1,3 +1,11 @@

1+# 1.1.0.0 (??)

3+* Fixes a bug where cartesian products of queries using `catListTable`, `catNonEmptyTable`, `catList` and `catNonEmpty` would incorrectly be zipped instead.

5+* Simplify `evaluate` to run directly inside the `Query` monad, rendering the `Evaluate` monad unnecessary.

7+* Rename `whereExists` and `whereNotExists` to `present` and `absent` respectively.

19# 1.0.0.1 (2021-06-21)

210

311This release contains various fixes for documentation.

docs/concepts/queries.rst+6−6

@@ -138,20 +138,20 @@ a query. The above query could thus be written as::

138138

139139``where_`` and ``filter`` allow you to filter rows based on an expression, but

140140sometimes we want to filter based on another query. For this, Rel8 offers

141−``whereExists`` and ``whereNotExists``. For example, if all blog posts have a

142−list of tags, we could use ``whereExists`` to find all blog posts that have been

141+``present`` and ``absent``. For example, if all blog posts have a

142+list of tags, we could use ``present`` to find all blog posts that have been

143143tagged as "Haskell"::

144144

145145 blogPost <- each blogPostSchema

146− whereExists do

146+ present do

147147 filter (("Haskell" ==.) . tagName) =<< tagFromBlogPost blogPost

148148

149−Notice that this example uses ``whereExists`` with a query that itself uses

150−``filter``. For each blog post, ``whereExists`` causes that row to be selected

149+Notice that this example uses ``present`` with a query that itself uses

150+``filter``. For each blog post, ``present`` causes that row to be selected

151151only if the associated query finds a tag for that blog post with the ``tagName``

152152"Haskell".

153153

154−Like ``filter`` there is also a chaining variant of ``whereExists`` - ``with``.

154+Like ``filter`` there is also a chaining variant of ``present`` - ``with``.

155155We could rewrite the above query using ``with`` as::

156156

157157 haskellBlogPost <-

src/Rel8.hs+2−2

@@ -178,8 +178,8 @@ module Rel8

178178 -- ** Filtering

179179 , filter

180180 , where_

181− , whereExists

182− , whereNotExists

181+ , present

182+ , absent

183183 , distinct

184184 , distinctOn

185185 , distinctOnBy

src/Rel8/Query/Exists.hs+12−12

@@ -2,8 +2,8 @@

33module Rel8.Query.Exists

44 ( exists, inQuery

5− , whereExists, with, withBy

6− , whereNotExists, without, withoutBy

5+ , present, with, withBy

6+ , absent, without, withoutBy

77 )

88where

@@ -25,7 +25,7 @@ import Rel8.Table.Maybe ( isJustTable )

2525

2626-- | Checks if a query returns at least one row.

2727exists :: Query a -> Query (Expr Bool)

28−exists = fmap isJustTable . optional . whereExists

28+exists = fmap isJustTable . optional . present

2929-- FIXME: change this when b7aacc07c6392654cae439fc3b997620c3aa7a87 makes it

3030-- into a release of Opaleye

3131

@@ -34,23 +34,23 @@ inQuery :: EqTable a => a -> Query a -> Query (Expr Bool)

3434inQuery a = exists . (>>= filter (a ==:))

3535

3636

37−-- | Produce the empty query if the given query returns no rows. @whereExists@

37+-- | Produce the empty query if the given query returns no rows. @present@

3838-- is equivalent to @WHERE EXISTS@ in SQL.

39−whereExists :: Query a -> Query ()

40−whereExists = mapOpaleye Opaleye.restrictExists

39+present :: Query a -> Query ()

40+present = mapOpaleye Opaleye.restrictExists

4141

4242

43−-- | Produce the empty query if the given query returns rows. @whereNotExists@

43+-- | Produce the empty query if the given query returns rows. @absent@

4444-- is equivalent to @WHERE NOT EXISTS@ in SQL.

45−whereNotExists :: Query a -> Query ()

46−whereNotExists = mapOpaleye Opaleye.restrictNotExists

45+absent :: Query a -> Query ()

46+absent = mapOpaleye Opaleye.restrictNotExists

4747

4848

4949-- | @with@ is similar to 'filter', but allows the predicate to be a full query.

5050--

51−-- @with f a = a <$ whereExists (f a)@, but this form matches 'filter'.

51+-- @with f a = a <$ present (f a)@, but this form matches 'filter'.

5252with :: (a -> Query b) -> a -> Query a

53−with f a = a <$ whereExists (f a)

53+with f a = a <$ present (f a)

5454

5555

5656-- | Like @with@, but with a custom membership test.

@@ -60,7 +60,7 @@ withBy predicate bs = with $ \a -> bs >>= filter (predicate a)

6060

6161-- | Filter rows where @a -> Query b@ yields no rows.

6262without :: (a -> Query b) -> a -> Query a

63−without f a = a <$ whereNotExists (f a)

63+without f a = a <$ absent (f a)

6464

6565

6666-- | Like @without@, but with a custom membership test.