diff --git a/LICENSE b/LICENSE
index 6352157..e69de29 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,21 +0,0 @@
-MIT License
-
-Copyright (c) 2025 Tan Kian-ting <chenjt30@gmail.com> and contributors
-
-Permission is hereby granted, free of charge, to any person obtaining a copy
-of this software and associated documentation files (the "Software"), to deal
-in the Software without restriction, including without limitation the rights
-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions:
-
-The above copyright notice and this permission notice shall be included in all
-copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
diff --git a/Project.toml b/Project.toml
index 5faab6e..9d4a457 100644
--- a/Project.toml
+++ b/Project.toml
@@ -3,6 +3,11 @@ uuid = "de6df24e-a306-4916-96f6-3ab6c7568c2f"
 authors = ["Tan Kian-ting <chenjt30@gmail.com> and contributors"]
 version = "1.0.0-DEV"
 
+[deps]
+ArgParse = "c7e460c6-2fb9-53a9-8c5b-16f535851c63"
+ParserCombinator = "fae87a5f-d1ad-5cf0-8f61-c941e1580b46"
+libharu_jll = "d4e8948d-4b7e-5538-9d15-404f6f0a9070"
+
 [compat]
 julia = "1.6.7"
 
diff --git a/example/ex1 copy.ug b/example/ex1 copy.ug
new file mode 100644
index 0000000..fc7d141
--- /dev/null
+++ b/example/ex1 copy.ug	
@@ -0,0 +1,7 @@
+%123%@foo  text%456 7%  %
+
+8 9 10%
+
+{@foo}
+
+{@foo|@bar}
\ No newline at end of file
diff --git a/example/ex1.ug b/example/ex1.ug
new file mode 100644
index 0000000..a8c2978
--- /dev/null
+++ b/example/ex1.ug
@@ -0,0 +1,2 @@
+@foo
+{@foo|@bar|12\|}
\ No newline at end of file
diff --git a/src/parsing.jl b/src/parsing.jl
new file mode 100644
index 0000000..534e124
--- /dev/null
+++ b/src/parsing.jl
@@ -0,0 +1,52 @@
+module Parsing
+using ParserCombinator
+abstract type Node end
+struct ID<:Node val end
+struct SEQ<:Node val end # like (a b c) in scheme
+struct ELE<:Node val end #an element in a seq
+struct ESC_CHAR<:Node val end # character preceded by escape char "\"
+
+#=
+grammar rules of uahgi
+=#
+
+comment = p"\%[^%]+\%"
+newline = p"(\r?\n)"
+space = p"[ \t]"
+
+id_name = p"[_a-zA-Z][_0-9a-zA-Z]*" > ID
+id = E"@" + id_name
+
+char = p"[^ \n\r\t\\]"#[1:2,:?]
+
+# chars should be preceded by "\" are \, {, }, |, @, %
+esc_char = p"[\{\|\}\@\%]" > ESC_CHAR
+esc_combined = E"\\" + esc_char
+#=
+seq = (foo x1 x2 " ")
+=> {@foo|x1|x2| }
+=#
+char_and_combined = char | esc_combined
+seq_item = id | Repeat(char_and_combined) |> ELE
+seq_item_rest = E"|" + seq_item
+seq_inner = seq_item + (seq_item_rest)[0:end] |> SEQ
+seq = E"{" + seq_inner + E"}"
+
+
+part =  seq | comment | space | newline | id | char
+all = Repeat(part) + Eos()
+
+function parse(input)
+    print(input)
+    b = parse_one(input, all)
+    print("\n" * string(b) * "\n")
+    
+    #print(parse_one(, Pattern(r".b.")))
+end
+# Write your package code here.
+#export dog
+
+#dog = 1.2
+
+
+end
\ No newline at end of file
diff --git a/src/uahgi.jl b/src/uahgi.jl
index 16191e7..08a57bf 100644
--- a/src/uahgi.jl
+++ b/src/uahgi.jl
@@ -1,5 +1,31 @@
 module uahgi
+include("./parsing.jl")
+using .Parsing
+using ArgParse
 
-# Write your package code here.
+function parse_commandline()
+    #= please see:
+    https://carlobaldassi.github.io/ArgParse.jl/stable/
+    =#
+    s = ArgParseSettings()
 
+    @add_arg_table! s begin
+        "FILE"
+            help = "the file path to be converted."
+            required = true
+    end
+
+    return parse_args(s)
 end
+
+
+function main()
+    parsed_args = parse_commandline()
+    file_path = parsed_args["FILE"]
+    file_content = open(f->read(f, String), file_path)
+    Parsing.parse(file_content)
+end
+
+main()
+end
+