Now that we have defined what we want the Sequence language to look like, we need to formalize this in a grammar and then build a parser to parse our input into an Abstract Syntax Tree

Even a tiny language as Sequnce requires a careful and iterative process, you need to consider both the semantics and the synatax.

The need for different types of computer languages is growing rapidly — luckily it turns out that creating your own Domain Specific Language does not have to be all that hard.