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Creating a programming language

Creating a programming language

Programming is hard. Making programming languages is harder. Or so people think. The truth is that making a programming language is just a series of small steps, using regular language constructs. It's so easy, we'll make one in this talk.

Christopher Pitt

October 05, 2014

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  1. Grammar → Rules which define structure/syntax sentence : subject verb

    object | subject verb → Each rule is called a lexeme sentence is a lexeme, subject is a lexeme etc. definition : type identifier = value | type identifier
  2. Lexer → Breaks a code string into tokens /(integer)/ =

    ["type", "integer"] → Ignores code heirarchy ["if"], ["("], ["identifier", "x"], ["=="], ["number", "5"]... ["type", "integer"], ["identifier", "minutes"], ["assign"], ...
  3. Parser → Arranges tokens into a heirarchy ["if", ["equals", [["identifier",

    "x"], ["number", "5"]]]]... → Checks tokens for syntax errors Parse error: parse error, expecting T_PAAMAYIM_NEKUDOTAYIM ["definition", [["type", "number"], ["identifier", "minutes"], ["number", "45"]]]
  4. Abstract Syntax Tree → Represents constructs in the compiler's language

    new While($conditionTokens, $bodyTokens) new Definition($typeToken, $identifierToken, $valueToken)
  5. Interpreter → Calculates an immediate effect $foreach->affect($context) → Always accepts

    and returns a context $definition->applyToContext($context)
  6. Compiler → Writes the Abstract Syntax Tree into a new

    language $compiler->render($switch) → Also checks nodes for syntax errors in target language $definition->renderWithContext($context)
  7. All together! → integer minutes = 45 → ["type", "integer"],

    ["identifier", "minutes"], ["assign"], ["number", "45"] → ["definition", [["type", "number"], ["identifier", "minutes"], ["number", "45"]]] → new Definition($typeToken, $identifierToken, $valueToken) → $definition->renderWithContext($context) $minutes = 45;