Node:Writing Defuns, Next:Buffer Walk Through, Previous:Practicing Evaluation, Up:Top

3 How To Write Function Definitions

When the Lisp interpreter evaluates a list, it looks to see whether the first symbol on the list has a function definition attached to it; or, put another way, whether the symbol points to a function definition. If it does, the computer carries out the instructions in the definition. A symbol that has a function definition is called, simply, a function (although, properly speaking, the definition is the function and the symbol refers to it.)

• Primitive Functions:
• defun: The defun special form.
• Install: Install a function definition.
• Interactive: Making a function interactive.
• Interactive Options: Different options for interactive.
• Permanent Installation: Installing code permanently.
• let: Creating and initializing local variables.
• if: What if?
• else: If--then--else expressions.
• Truth & Falsehood: What Lisp considers false and true.
• save-excursion: Keeping track of point, mark, and buffer.
• Review:
• defun Exercises: