'tag' describes the token. Lex takes in the following: input_str: String, singlecharh: Function/1, multicharh: Function/1, otherwise: Function/0, # optional

input_str the program to lex singlecharh the function that returns {bool, atom} where 'bool' is given when a match is made, and 'atom' is given as the argument for the tag to the match. For example, a function that matches "(" to return {true, :oparen} while also matching ")" to return {true, :cparen} 'singlecharh' should contain what tokens to match and their tag. Code example (of a function taking 'character' as its sole argument)

cond do
char == "(" ->
    {true, :oparen}
char == ")"->
    {true, :cparen}
char == "!" ->
    {true, :not}
true ->
    {false, :pass}
end

Example on repository. This will allow the lexer to lex these characters. Given a string "()" the lexer will be able to lex that into:

[{"(", :oparen}, {")", :cparen}]

multichar: the function that returns {bool, atom} where 'bool' is given as 'true' when the character satisfies the required condition, and 'atom' is the tag. For example, a function that matches alphanumeric characters or underscore while also matching another multi-character pattern. Effectively used the same way as 'singlecharh'. Example in repository.

otherwise: what to execute if elexer encounters a foreigh character. For example, if 'otherwise' is a function that prints an error, it will print the error when a foreigh character is found.

To give lex these arguments, you should use the &function/arity syntax, where 'arity' is the number of arguments.

Does nothing. Used when a function is to be called, but no effect is desired.

The actual lexing function. Not for your use, but for your contribution. See the lex function instead if you plan to use it.