# Let's Build A Simple Interpreter. Part 12.

DevFeed: [Let's Build A Simple Interpreter. Part 12.](<https://devfeed.tech/articles/let-s-build-a-simple-interpreter-part-12-33315.md>)

Original publisher: [Read original article](<https://ruslanspivak.com/lsbasi-part12/>)

Author: Ruslan Spivak

Published: 2016-12-01T21:20:00Z

Content type: tutorial

Language: en

Sources: [Ruslan Spivak](<https://devfeed.tech/sources/ruslan-spivak.md>)

Topics: [Parsing](<https://devfeed.tech/topics/parsing.md>), [syntax](<https://devfeed.tech/topics/syntax.md>), [Code](<https://devfeed.tech/topics/code.md>), [identifier](<https://devfeed.tech/topics/identifier.md>)

Tags: [blog](<https://devfeed.tech/tags/blog.md>), [code](<https://devfeed.tech/tags/code.md>), [identifier](<https://devfeed.tech/tags/identifier.md>), [lexer](<https://devfeed.tech/tags/lexer.md>), [syntax](<https://devfeed.tech/tags/syntax.md>)

## AI overview

Part 12 of a tutorial series explains how to extend a simple interpreter to parse Pascal procedure declarations. It covers procedure syntax, nested declarations, grammar updates, syntax diagrams, and lexer changes for a PROCEDURE token.

## Source excerpt

"Be not afraid of going slowly; be afraid only of standing still." - Chinese proverb. Hello, and welcome back! Today we are going to take a few more baby steps and learn how to parse Pascal procedure declarations. What is a procedure declaration? A procedure declaration is a language construct that ...