ref: 13efe91101a11f41caf6321a8b2fbdd96ef9927a
dir: pprolog/TODO
* Stop comparing strings all the time * Stop copying the entire goal stack into every choicepoint * Modules (I try to do something like SWI prolog for now, but I know there is also an iso standard) The following builtins: '='/2 needs to do something about the occurs check unify_with_occurs_check/2: not implemented '\\='/2: handle occurs check * Handle overflow and uderflow in arithmetic * Variables should be compared and printed in a way that makes sense. Right now, their number is changed when a clause is used, but their name remains the same, so prints will be bad. * Write a loader in prolog, that calls builtins to activate the C functions needed. This means we can do some syntax transformations and handle directives in prolog code, instead of C. The "bootstrap" modules will have to be written in a way the original C loader understands, but everything after that can use the full feature set. Steps: 1) Change the lexer and parser so they carry around their state instead of global variables. 2) Make it possible to evaluate a query using 'evalquery' even when another query is running. This means no more global variables there either. 3) Create a "loading context" which is indexed by a prolog term and consists of: * Lexer + parser state * module loading state 4) Loading then becomes: 1) Create loading context 2) Open file 3) Repeatedly read terms using read_term 4) Inspect the term (clause or directive?) and act on it, using builtints and reference to context 5) Close the file and context