fclabels 0.9.0 → 0.9.1

raw patch · 1 files changed

+12/−27 lines, 1 filesPVP ok

version bump matches the API change (PVP)

API changes (from Hackage documentation)

Files

• fclabels.cabal +12/−27

@@ -1,5 +1,5 @@ Name:            fclabels-Version:         0.9.0+Version:         0.9.1 Author:          Sebastiaan Visser, Erik Hesselink, Chris Eidhof, Sjoerd Visscher. Synopsis:        First class accessor labels implemented as lenses. @@ -38,22 +38,8 @@                  .                  > $(mkLenses [''Person, ''Place])                  .-                 Lens functions will be generated, lens type signatures will-                 not be generated. This is actually not that bad, by writing the signatures-                 Let's give the functions a signature by hand:-                 .-                 > name      :: Person :-> String-                 > age       :: Person :-> Int-                 > isMale    :: Person :-> Bool-                 > place     :: Person :-> Place-                 > city      :: Place :-> String-                 > country   :: Place :-> String-                 > continent :: Place :-> String-                 .-                 These type signatures look very similar to the function types-                 for normal record labels, except that the additional colon-                 indicates a true first class lens.  These lenses can be used-                 to get, set and modify the value and are fully composable.+                 These lenses can be used to get, set and modify the value and+                 are fully composable.                  .                  Now let's look at this example. This 71 year old fellow, called Jan,                  is my neighbour and didn't mind using him as an example:@@ -62,24 +48,24 @@                  > jan = Person "Jan" 71 True (Place "Utrecht" "The Netherlands" "Europe")                  .                  When we want to be sure Jan is really as old as he claims we-                 can use the @get@ function to get the age out as an integer:+                 can use the @getL@ function to get the age out as an integer:                  .                  > hisAge :: Int-                 > hisAge = get age jan+                 > hisAge = getL age jan                  .                  Consider he now wants to move to Amsterdam: what better place                  to spend your old days. Using composition we can change the                  city value deep inside the structure:                  .                  > moveToAmsterdam :: Person -> Person-                 > moveToAmsterdam = set (city . place) "Amsterdam"+                 > moveToAmsterdam = setL (city . place) "Amsterdam"                  .                  > moveToAmsterdam jan ==                  >  Person "Jan" 71 True (Place "Amsterdam" "The Netherlands" "Europe")                  .                  Composition is done using the dot operator which is part of                  the @Control.Category@ module. Make sure to import this module-                 and hide the default @(.)@, @id@ and @mod@ function from the+                 and hide the default @(.)@, @id@ and @modL@ function from the                  Prelude.                  .                  Now, because Jan is an old guy, moving to another city is not a@@ -91,7 +77,7 @@                  @Applicative@ functor instance:                  .                  > ageAndCity :: Person :-> (Int, String)-                 > ageAndCity = Label $ (,) <$> fst `for` age <*> snd `for` (city . place)+                 > ageAndCity = Lens $ (,) <$> fst `for` age <*> snd `for` (city . place)                  .                  Because the applicative type class on its own is not very                  capable of expressing bidirectional relations, which we need@@ -104,11 +90,11 @@                  .                  Now that we have an appropriate age+city view on the @Person@                  data type (which is itself a lens again), we can use the-                 @mod@ function to make Jan move to Amsterdam over exactly two+                 @modL@ function to make Jan move to Amsterdam over exactly two                  years:                  .                  > moveToAmsterdamOverTwoYears :: Person -> Person-                 > moveToAmsterdamOverTwoYears = mod ageAndCity (\(a, b) -> (a+2, "Amsterdam"))+                 > moveToAmsterdamOverTwoYears = modL ageAndCity (\(a, b) -> (a+2, "Amsterdam"))                  .                  > moveToAmsterdamOverTwoYears jan ==                  >  Person "Jan" 73 True (Place "Amsterdam" "The Netherlands" "Europe")@@ -123,18 +109,17 @@                  do the following:                  .                  > ageAsString :: Person :-> String-                 > ageAsString :: (show <-> read) `iso` age+                 > ageAsString :: (show :<->: read) % age                  .                  A final note: this library might look cryptic at first sight, but give it a                  try, it is not that hard.                  .                  .                  > CHANGELOG-                 >   0.4.2 -> 1.0.0+                 >   0.4.2 -> 0.9.1                  >   - Added askM and localM for running lenses inside MonadReader.                  >   - Minor documentaion update.                  >   - Exported Point internals.-                 >   - Renamed Lens to Bijection, which is more correct.                  >   - Renamed Label to Lens.  Maintainer:      Sebastiaan Visser <haskell@fvisser.nl>