first commit

.gitignore

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+.stack-work
+dist-newstyle

CHANGELOG.md

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+# Changelog for `varcomp`
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to the
+[Haskell Package Versioning Policy](https://pvp.haskell.org/).
+
+## Unreleased
+
+## 0.1.0.0 - YYYY-MM-DD

LICENSE

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+Copyright 2024 Author name here
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1.  Redistributions of source code must retain the above copyright notice, this
+    list of conditions and the following disclaimer.
+
+2.  Redistributions in binary form must reproduce the above copyright notice,
+    this list of conditions and the following disclaimer in the documentation
+    and/or other materials provided with the distribution.
+
+3.  Neither the name of the copyright holder nor the names of its contributors
+    may be used to endorse or promote products derived from this software
+    without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

README.md

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+# `varcomp` -- Variadic function composition
+
+Variadic function composition done via the `.**.` operator.
+
+## Usage
+
+```haskell
+import Variadic.Composition (Compose ((.**.)))
+
+-- Simple composition
+
+g :: Char -> String
+g = const "hello"
+
+-- One argument
+
+f0 :: Int -> Char
+f0 = undefined
+
+h1 :: Int -> String
+h1 = g .**. f0
+
+-- Two arguments
+
+f2 :: Int -> Double -> Char
+f2 = undefined
+
+h2 :: Int -> Double -> String
+h2 = g .**. f2
+
+-- Three arguments
+
+f3 :: Int -> Double -> String
+f3 = undefined
+
+h3 :: Int -> Double -> Char
+h3 = g .**. f3
+```

Setup.hs

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+import Distribution.Simple
+main = defaultMain

src/Variadic/Composition.hs

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+-- | Variadic composition
+module Variadic.Composition (Compose (..)) where
+
+-- | Variadic composition
+class Compose a b c d e where
+ -- | Compose two functions
+ (.**.) :: (a -> b) -> (c -> d) -> (c -> e)
+
+instance Compose a b c a b where
+ (.**.) = (.)
+ {-# INLINE (.**.) #-}
+
+instance (Compose a b f d e) => Compose a b c (f -> d) (f -> e) where
+ f .**. g = \x -> f .**. g x
+ {-# INLINE (.**.) #-}

stack.yaml

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+# This file was automatically generated by 'stack init'
+#
+# Some commonly used options have been documented as comments in this file.
+# For advanced use and comprehensive documentation of the format, please see:
+# https://docs.haskellstack.org/en/stable/yaml_configuration/
+
+# A 'specific' Stackage snapshot or a compiler version.
+# A snapshot resolver dictates the compiler version and the set of packages
+# to be used for project dependencies. For example:
+#
+# snapshot: lts-22.28
+# snapshot: nightly-2024-07-05
+# snapshot: ghc-9.6.6
+#
+# The location of a snapshot can be provided as a file or url. Stack assumes
+# a snapshot provided as a file might change, whereas a url resource does not.
+#
+# snapshot: ./custom-snapshot.yaml
+# snapshot: https://example.com/snapshots/2024-01-01.yaml
+snapshot:
+  url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/23/0.yaml
+
+# User packages to be built.
+# Various formats can be used as shown in the example below.
+#
+# packages:
+# - some-directory
+# - https://example.com/foo/bar/baz-0.0.2.tar.gz
+#   subdirs:
+#   - auto-update
+#   - wai
+packages:
+- .
+# Dependency packages to be pulled from upstream that are not in the snapshot.
+# These entries can reference officially published versions as well as
+# forks / in-progress versions pinned to a git hash. For example:
+#
+# extra-deps:
+# - acme-missiles-0.3
+# - git: https://github.com/commercialhaskell/stack.git
+#   commit: e7b331f14bcffb8367cd58fbfc8b40ec7642100a
+#
+# extra-deps: []
+
+# Override default flag values for project packages and extra-deps
+# flags: {}
+
+# Extra package databases containing global packages
+# extra-package-dbs: []
+
+# Control whether we use the GHC we find on the path
+# system-ghc: true
+#
+# Require a specific version of Stack, using version ranges
+# require-stack-version: -any # Default
+# require-stack-version: ">=3.1"
+#
+# Override the architecture used by Stack, especially useful on Windows
+# arch: i386
+# arch: x86_64
+#
+# Extra directories used by Stack for building
+# extra-include-dirs: [/path/to/dir]
+# extra-lib-dirs: [/path/to/dir]
+#
+# Allow a newer minor version of GHC than the snapshot specifies
+# compiler-check: newer-minor

stack.yaml.lock

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+# This file was autogenerated by Stack.
+# You should not edit this file by hand.
+# For more information, please see the documentation at:
+#   https://docs.haskellstack.org/en/stable/lock_files
+
+packages: []
+snapshots:
+- completed:
+    sha256: 9444fadfa30b67a93080254d53872478c087592ad64443e47c546cdcd13149ae
+    size: 678857
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/23/0.yaml
+  original:
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/23/0.yaml

test/Spec.hs

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+module Main (main) where
+
+import Test.Hspec
+import Variadic.Composition (Compose ((.**.)))
+
+-- Test functions
+toString :: Int -> String
+toString = show
+
+addOne :: Int -> Int
+addOne = (+ 1)
+
+add :: Int -> Int -> Int
+add x y = x + y
+
+concat3 :: String -> String -> String -> String
+concat3 x y z = x ++ y ++ z
+
+main :: IO ()
+main = hspec $ do
+  describe "Variadic composition" $ do
+    it "works with single argument functions" $ do
+      (toString .**. addOne) 5 `shouldBe` "6"
+
+    it "works with two argument functions" $ do
+      (toString .**. add) 1 2 `shouldBe` "3"
+
+    it "works with three argument functions" $ do
+      (toString .**. concat3) "a" "b" "c" `shouldBe` "abc"
+
+    it "maintains function behavior" $ do
+      let f = toString .**. addOne
+      let g = toString . addOne
+      f 10 `shouldBe` g 10 

varcomp.cabal

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+cabal-version:       2.2
+
+name:                varcomp
+version:             0.1.0.0
+synopsis:            Variadic function composition
+description:         Variadic function composition done via the (.**.) operator
+homepage:            https://github.com/axionbuster/varcomp#readme
+license:             BSD-3-Clause
+license-file:        LICENSE
+author:              "buster"
+maintainer:          "[email protected]"
+copyright:           2024 "buster"
+category:            Data
+build-type:          Simple
+extra-source-files:  README.md
+                     CHANGELOG.md
+
+library
+  hs-source-dirs:      src
+  exposed-modules:     Variadic.Composition
+  build-depends:       base >= 4.7 && < 5
+  default-language:    Haskell2010
+  default-extensions:  MultiParamTypeClasses, FlexibleInstances
+  ghc-options:         -Wall
+                       -Wcompat
+                       -Widentities
+                       -Wincomplete-record-updates
+                       -Wincomplete-uni-patterns
+                       -Wmissing-export-lists
+                       -Wmissing-home-modules
+                       -Wpartial-fields
+                       -Wredundant-constraints
+
+test-suite varcomp-test
+  type:                exitcode-stdio-1.0
+  hs-source-dirs:      test
+  main-is:             Spec.hs
+  build-depends:       base
+                     , varcomp
+                     , hspec >= 2.7.1
+  ghc-options:         -threaded
+                       -rtsopts
+                       -with-rtsopts=-N
+                       -Wall
+  default-language:    Haskell2010
+  default-extensions:  MultiParamTypeClasses, FlexibleInstances
+
+source-repository head
+  type:     git
+  location: https://github.com/githubuser/varcomp