How to develop a programming language

Here are some tips for developing a new programming language:

• Decide on the language’s purpose and goals. What types of problems is it aiming to solve? Will it be general-purpose or domain-specific? These decisions will inform other aspects of the language design.
• Choose the syntax and semantics. The syntax refers to the structure and format of the code, while the semantics refer to what the code means and how it behaves. Popular syntax styles include curly-brace languages like C and Java, whitespace-significant languages like Python, and functional languages like ML.
• Define the core language elements like variables, data types, expressions, statements, etc. Consider what built-in data types, operators, control flow structures, modularity mechanisms, etc. to provide.
• Design the compiler and/or interpreter. This is the software that takes code written in your language and converts it into executable machine code. Decide whether to compile directly to machine code or to bytecode for a virtual machine.
• Build development tools like debuggers, profilers, linters, etc. to improve the coding experience. An IDE can also be created.
• Write a formal language specification defining the syntax and semantics rigorously. This helps implementers stay consistent.
• Prototype rapidly and iterate based on feedback. Test with sample programs and fix issues. Grow the language capabilities over time.
• Build up libraries and frameworks to expand the language capabilities and let programmers solve real-world problems.
• Cultivate a community providing learning resources, documentation, libraries and engaging users for feedback.
• Consider open sourcing the language specifications and tools to attract more contributors.

The key is starting small, getting feedback often, adding features incrementally and building an ecosystem around your language.