This is a toy lisp implementation loosely based on Paul Graham's The Roots of Lisp (postscript file).

Working:

• car (head)
• cdr (tail)
• cons
• if
• quote
• atom
• eq
• let
• lambda
  • recursion
  • lexical scope
  • closures
• define (for repl only)
• integer arithmetic
  • add
  • subtract
  • multiply
  • divide
• non-alphabetical symbols
• inspect
• variadic functions
• repl works on multiline functions
• cond
• program termination with nonzero return in error cases

TODO:

• bootstrap
• strings
• garbage collection

known bugs:

Side-effects in "if" or "cond" forms don't work:

  (define l (quote (1 2)))
  (if (inspect (cons 3 l)) 1 0)
  (inspect l)

Updated testing strategy:

• input and expected output files
• shell script that executes the input files with the current version of roots and runs diff on the input and output, printing the filenames of the diffs
• git precommit hook that updates the diffs