Add solving expressions

.gitignore

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+dist
+dist-*
+cabal-dev
+*.o
+*.hi
+*.hie
+*.chi
+*.chs.h
+*.dyn_o
+*.dyn_hi
+.hpc
+.hsenv
+.cabal-sandbox/
+cabal.sandbox.config
+*.prof
+*.aux
+*.hp
+*.eventlog
+.stack-work/
+cabal.project.local
+cabal.project.local~
+.HTF/
+.ghc.environment.*

CHANGELOG.md

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+# Revision history for really-bad-compiler-in-haskell
+
+## 0.1.0.0 -- YYYY-mm-dd
+
+* First version. Released on an unsuspecting world.

README.md

@@ -1,3 +1,30 @@
-# really-bad-compiler-in-haskell
+# Really Bad Compiler in Haskell
 
-A compiler written in Haskell that is really bad (I do not know what language I am going to compile yet)
+A compiler written in Haskell that is really bad (I do not know what language I am going to compile yet). Built for the Introduction to Compiler Design class at The University of Texas at Dallas.
+
+Main repo: https://git.sudoer.ch/me/really-bad-compiler-in-haskell
+
+## Build Instructions
+
+- Clone the repo.
+- Use `ghcup` to install all of the Haskell tools.
+- Use `stack build` and `stack run <file>` to run the program.
+
+## Credits
+
+### Learning Resources Used
+
+- Introduction to Compiler Design class at The University of Texas at Dallas, taught by Charles Averill
+- learnyouahaskell.com (for learning Haskell basics)
+- https://akashagrawal.me/2017/01/19/beginners-guide-to-megaparsec.html
+- https://markkarpov.com/tutorial/megaparsec.html (for help writing a Haskell equation parser)
+
+### Tools
+
+- Language: Haskell
+- Haskell tools: GHCup, Stack, Cabal
+- Libraries: megaparsec, parser-combinators, text
+- IDE: VSCodium
+- Git platform: Forgejo
+- AI: Phind
+- Search: Kagi, Stack Overflow

app/Eval/Expression.hs

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+module Eval.Expression (evalExpr) where
+
+import Objects.Expression
+
+eval :: Expr -> Int
+eval (Lit x) = x
+eval (Add x y) = eval x + eval y
+eval (Sub x y) = eval x - eval y
+eval (Mul x y) = eval x * eval y
+eval (Div x y) = eval x `div` eval y
+
+evalExpr :: Expr -> Int
+evalExpr = eval

app/Main.hs

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+module Main (main) where
+
+import Data.Either
+import Eval.Expression
+import Objects.Expression
+import Parser.Expression
+import System.Environment
+import Text.Megaparsec
+
+parseResult :: ParseResult
+parseResult = parseExpr "2+3*4"
+
+getRight :: ParseResult -> Expr
+getRight (Right r) = r
+
+expr = getRight parseResult
+
+result = evalExpr expr
+
+main = do
+  print result

app/Objects/Expression.hs

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+module Objects.Expression
+  ( Expr
+      ( Lit,
+        Add,
+        Sub,
+        Mul,
+        Div
+      ),
+      -- solve,
+  )
+where
+
+data Expr
+  = Lit Int
+  | Add Expr Expr
+  | Sub Expr Expr
+  | Mul Expr Expr
+  | Div Expr Expr
+  deriving (Show)

app/Parser/Expression.hs

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+module Parser.Expression (parseExpr, ParseResult) where
+
+import Control.Monad.Combinators.Expr
+import Data.Void (Void)
+import Objects.Expression
+import Text.Megaparsec as MP
+import Text.Megaparsec.Char as C
+import Text.Megaparsec.Char.Lexer as L
+
+type Parser = Parsec Void String
+
+lexemeParser :: Parser a -> Parser a
+lexemeParser = L.lexeme C.space
+
+symbolParser :: String -> Parser String
+symbolParser = L.symbol C.space
+
+intParser :: Parser Int
+intParser = lexemeParser L.decimal
+
+term :: Parser Expr
+term = Lit <$> intParser
+
+table :: [[Operator Parser Expr]]
+table =
+  [ [ binaryOp "*" Mul,
+      binaryOp "/" Div
+    ],
+    [ binaryOp "+" Add,
+      binaryOp "-" Sub
+    ]
+  ]
+
+binaryOp name f = InfixL (f <$ symbolParser name)
+
+expr :: Parser Expr
+expr = makeExprParser term table
+
+type ParseResult = Either (ParseErrorBundle String Void) Expr
+
+parseExpr :: String -> ParseResult
+parseExpr = MP.parse (C.space *> expr <* eof) ""
+
+-- parseE = parseExpr

really-bad-compiler-in-haskell.cabal

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+cabal-version:      2.4
+name:               really-bad-compiler-in-haskell
+version:            0.1.0.0
+
+-- A short (one-line) description of the package.
+-- synopsis:
+
+-- A longer description of the package.
+-- description:
+
+-- A URL where users can report bugs.
+-- bug-reports:
+
+-- The license under which the package is released.
+-- license:
+author:             sudoer777
+maintainer:         git@sudoer.ch
+
+-- A copyright notice.
+-- copyright:
+-- category:
+extra-source-files:
+    CHANGELOG.md
+    README.md
+
+executable really-bad-compiler-in-haskell
+    main-is:          Main.hs
+
+    -- Modules included in this executable, other than Main.
+    -- other-modules:
+
+    -- LANGUAGE extensions used by modules in this package.
+    -- other-extensions:
+    build-depends:    base ^>=4.16.4.0
+                    , megaparsec >= 9.2.2
+                    , parser-combinators
+                    , text
+    hs-source-dirs:   app
+    default-language: Haskell2010

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/
+
+# Resolver to choose 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:
+#
+# resolver: lts-3.5
+# resolver: nightly-2015-09-21
+# resolver: ghc-7.10.2
+#
+# 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.
+#
+# resolver: ./custom-snapshot.yaml
+# resolver: https://example.com/snapshots/2018-01-01.yaml
+resolver:
+  url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/20/26.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 resolver.
+# 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 local 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: ">=2.9"
+#
+# 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: 5a59b2a405b3aba3c00188453be172b85893cab8ebc352b1ef58b0eae5d248a2
+    size: 650475
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/20/26.yaml
+  original:
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/20/26.yaml