Creating A Programming Language integer minutes = 45; 

Grammar 

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 

Lexer 

Lexer → Breaks a code string into tokens /(integer)/ = ["type", "integer"] → Ignores code heirarchy ["if"], ["("], ["identifier", "x"], ["=="], ["number", "5"]... ["type", "integer"], ["identifier", "minutes"], ["assign"], ... 

Parser 

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"]]] 

Abstract Syntax Tree 

Abstract Syntax Tree → Represents constructs in the compiler's language new While($conditionTokens, $bodyTokens) new Definition($typeToken, $identifierToken, $valueToken) 

Interpreter 

Interpreter → Calculates an immediate effect $foreach->affect($context) → Always accepts and returns a context $definition->applyToContext($context) 

Compiler 

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) 

All together! 

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;