Complete StateT

asarkar · Dec 30, 2024 · ab96305 · ab96305
1 parent 7c00943
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Showing 19 changed files with 627 additions and 151 deletions.
diff --git a/README.md b/README.md
@@ -21,7 +21,7 @@ After this, we recommend the following progression of modules:
 * [Monad](src/Monad.hs)
 * [FileIO](src/FileIO.hs)
 * [State](src/State.hs)
-* StateT
+* [StateT](src/StateT.hs)
 * Extend
 * Comonad
 * Contravariant
@@ -59,7 +59,7 @@ To run a _specific test_:
 
 To run a file containing a `main` method:
 ```
-stack runhaskell app/Main.hs
+stack runhaskell <path/to/file> <arg1> <arg2>
 ```
 
 To run an executable listed in `package.yaml`:

diff --git a/share/a.txt → data/a.txt b/share/a.txt → data/a.txt
diff --git a/share/b.txt → data/b.txt b/share/b.txt → data/b.txt
diff --git a/share/c.txt → data/c.txt b/share/c.txt → data/c.txt
diff --git a/data/files.txt b/data/files.txt
@@ -0,0 +1,3 @@
+data/a.txt
+data/b.txt
+data/c.txt
diff --git a/fp-course-haskell.cabal b/fp-course-haskell.cabal
@@ -28,6 +28,7 @@ library
       Monad
       Optional
       State
+      StateT
       Validation
   other-modules:
       Paths_fp_course_haskell
@@ -37,7 +38,7 @@ library
       TupleSections
       DerivingStrategies
       InstanceSigs
-  ghc-options: -Werror -Weverything -Wno-missing-import-lists -Wno-missed-specializations -Wno-all-missed-specializations -Wno-missing-local-signatures -Wno-monomorphism-restriction -Wno-missing-safe-haskell-mode -Wno-safe -Wno-unsafe -Wno-implicit-prelude -Wno-prepositive-qualified-module -Wno-missing-kind-signatures -Wno-unused-top-binds -Wno-missing-export-lists -Wno-missing-role-annotations
+  ghc-options: -Werror -Weverything -Wno-missing-import-lists -Wno-missed-specializations -Wno-all-missed-specializations -Wno-missing-local-signatures -Wno-monomorphism-restriction -Wno-missing-safe-haskell-mode -Wno-safe -Wno-unsafe -Wno-implicit-prelude -Wno-prepositive-qualified-module -Wno-missing-kind-signatures -Wno-unused-top-binds -Wno-missing-export-lists -Wno-missing-role-annotations -Wno-type-defaults
   build-depends:
       base >=4.7 && <5
     , containers
@@ -55,6 +56,7 @@ test-suite fp-course-test
       Property
       SpecHook
       StateSpec
+      StateTSpec
       ValidationSpec
       Paths_fp_course_haskell
   hs-source-dirs:
@@ -63,7 +65,7 @@ test-suite fp-course-test
       TupleSections
       DerivingStrategies
       InstanceSigs
-  ghc-options: -Werror -Weverything -Wno-missing-import-lists -Wno-missed-specializations -Wno-all-missed-specializations -Wno-missing-local-signatures -Wno-monomorphism-restriction -Wno-missing-safe-haskell-mode -Wno-safe -Wno-unsafe -Wno-implicit-prelude -Wno-prepositive-qualified-module -Wno-missing-kind-signatures -Wno-unused-top-binds -Wno-missing-export-lists -Wno-missing-role-annotations
+  ghc-options: -Werror -Weverything -Wno-missing-import-lists -Wno-missed-specializations -Wno-all-missed-specializations -Wno-missing-local-signatures -Wno-monomorphism-restriction -Wno-missing-safe-haskell-mode -Wno-safe -Wno-unsafe -Wno-implicit-prelude -Wno-prepositive-qualified-module -Wno-missing-kind-signatures -Wno-unused-top-binds -Wno-missing-export-lists -Wno-missing-role-annotations -Wno-type-defaults
   build-depends:
       QuickCheck
     , base >=4.7 && <5

diff --git a/package.yaml b/package.yaml
@@ -39,6 +39,7 @@ ghc-options:
 - -Wno-unused-top-binds
 - -Wno-missing-export-lists
 - -Wno-missing-role-annotations
+- -Wno-type-defaults
 
 library:
   source-dirs: src

diff --git a/share/files.txt b/share/files.txt
diff --git a/src/FileIO.hs b/src/FileIO.hs
@@ -58,7 +58,7 @@ And c.txt, containing:
   the contents of c
 
 To test this module, load ghci in the root of the project directory, and do
-    >> :main "share/files.txt"
+    >> :main "data/files.txt"
 
 Example output:
 
@@ -69,14 +69,14 @@ Loading ...
 [ 1 of 28] Compiling (etc...
 ...
 Ok, modules loaded: Course, etc...
->> :main "share/files.txt"
-============ share/a.txt
+>> :main "data/files.txt"
+============ data/a.txt
 the contents of a
 
-============ share/b.txt
+============ data/b.txt
 the contents of b
 
-============ share/c.txt
+============ data/c.txt
 the contents of c
 
 -}
@@ -136,7 +136,7 @@ main :: IO ()
 main =
   L.getArgs >>= \case
     filename :. Nil -> run filename
-    _ -> L.putStrLn "usage: stack runhaskell src/FileIO.hs share/files.txt"
+    _ -> L.putStrLn "usage: stack runhaskell src/FileIO.hs data/files.txt"
 
 ----
 

diff --git a/src/State.hs b/src/State.hs
@@ -151,12 +151,9 @@ firstRepeat xs = eval (findM contains xs) S.empty
 contains :: (Ord a) => a -> State (Set a) Bool
 contains x = do
   seen <- get
-  if S.member x seen
-    then
-      A.pure True
-    else do
-      put (S.insert x seen)
-      A.pure False
+  let dup = S.member x seen
+  put $ S.insert x seen
+  A.pure dup
 
 -- | Remove all duplicate elements in a `List`.
 -- /Tip:/ Use `filtering` and `State` with a @Data.Set#Set@.