Added parser-combinator for expression parsing

package.yaml

@@ -21,8 +21,9 @@ description:         Please see the README on GitHub at <https://github.com/zyrr
 
 dependencies:
 - base >= 4.7 && < 5
-- megaparsec
 - text
+- megaparsec
+- parser-combinators
 
 ghc-options:
 - -Wall

stack.yaml

@@ -42,7 +42,7 @@ packages:
 #
 extra-deps: 
 - megaparsec-9.6.1
-# - text-2.0.2
+- parser-combinators-1.3.0
 
 # Override default flag values for local packages and extra-deps
 # flags: {}

stack.yaml.lock

@@ -11,6 +11,13 @@ packages:
       size: 1545
   original:
     hackage: megaparsec-9.6.1
+- completed:
+    hackage: parser-combinators-1.3.0@sha256:8659573e0d443d573f5b53f81b81dafbdc988d282b90c11e3da73562b4ea7876,1640
+    pantry-tree:
+      sha256: 4e23178c63f624bbe16342a9b3cfb4afdddee393ce0beec9b19cce0a0345a080
+      size: 795
+  original:
+    hackage: parser-combinators-1.3.0
 snapshots:
 - completed:
     sha256: 2fdd7d3e54540062ef75ca0a73ca3a804c527dbf8a4cadafabf340e66ac4af40

violet.cabal

@@ -25,7 +25,6 @@ source-repository head
 
 library
   exposed-modules:
-      Lexer
       Parser
       Syntax
   other-modules:
@@ -38,6 +37,7 @@ library
   build-depends:
       base >=4.7 && <5
     , megaparsec
+    , parser-combinators
     , text
   default-language: Haskell2010
 
@@ -53,6 +53,7 @@ executable violet-exe
   build-depends:
       base >=4.7 && <5
     , megaparsec
+    , parser-combinators
     , text
     , violet
   default-language: Haskell2010
@@ -70,6 +71,7 @@ test-suite violet-test
   build-depends:
       base >=4.7 && <5
     , megaparsec
+    , parser-combinators
     , text
     , violet
   default-language: Haskell2010