Wrote a basic parser

app/Main.hs

@@ -11,5 +11,28 @@ data Statement = Print Var | Assign Var Int | Add Var Var | While Var Code deriv
 
 type Code = [Statement]
 
+-- Part 1: Parser
+
+statementParser :: Parser Statement
+statementParser = try printParser <|> try assignParser <|> try addParser <|> whileParser
+
+printParser :: Parser Statement
+printParser = Print <$> (string "print" >> many1 space >> many1 letter)
+
+assignParser :: Parser Statement
+assignParser = Assign <$> many1 letter <*> (many1 space >> char '=' >> many1 space >> int)
+
+addParser :: Parser Statement
+addParser = Add <$> many1 letter <*> (many1 space >> string "+=" >> many1 space >> many1 letter)
+
+whileParser :: Parser Statement
+whileParser = While <$> (string "while" >> many1 space >> many1 letter) <*> (many1 space >> string "positive" >> many1 space >> char '{' >> many1 space >> many (statementParser <* many1 space) <* char '}')
+
+codeParser :: Parser Code
+codeParser = spaces >> many (statementParser <* many1 space) <* eof
+
 main :: IO ()
-main = someFunc
+main = do
+  fileText <- readFile "input.txt"
+  let parsed = parse codeParser "input.txt" fileText
+  print parsed

input.txt

@@ -0,0 +1,6 @@
+a = 5
+b = -1
+while a positive {
+  print a
+  a += b
+}