Creme
Creme is an implementation of a subset of the Kernel programming language in OCaml.
Requirements
- OCaml 4.00+
Examples
You can, of course, use Creme in a manner similar to you would with Scheme:
($define! map
($lambda (f ls)
($if (null? ls)
ls
(cons (f (car ls))
(map f (cdr ls))))))
Which defines an applicative combiner map. An applicative combiner will have its arguments evaluated before being passed to it.
The power of Kernel, however, comes from the $vau operative. An operative does not get its arguments evaluated. Instead, we combine $vau with the eval operative, which allows explicity evaluation of forms. This allows us to define syntax like $cond or $let:
($define! $cond
($vau clauses env
($define! aux
($lambda ((test . body) . clauses)
($if (eval test env)
(apply (wrap $sequence) body env)
(apply (wrap $cond) clauses env))))
($if (null? clauses)
#inert
(apply aux clauses))))
This means that unlike in Scheme, where macros aren't first-class, we get something similar to macros as first-class citizens. Neat.
Optimizations
While most of Kernel's features can be bootstrapped from a few primitives, it can lead to performance
issues. The biggest performance gain was gotten by rewriting the $sequence operative in OCaml. Further
performance gains were gotten by doing the same for $vau and $lambda.
% time ./creme-no-opt tests/tak.crm > /dev/null
./creme-no-opt tests/tak.crm > /dev/null 19.39s user 0.02s system 99% cpu 19.418 total
% time ./creme-opt-seq tests/tak.crm > /dev/null
./creme-opt-seq tests/tak.crm > /dev/null 5.13s user 0.01s system 99% cpu 5.142 total
% time ./creme-opt-seq-vau tests/tak.crm > /dev/null
./creme-opt-seq-vau tests/tak.crm > /dev/null 4.18s user 0.01s system 99% cpu 4.190 total
% time ./creme-opt-seq-vau-lambda tests/tak.crm > /dev/null
./creme-opt-seq-vau-lambda tests/tak.crm > /dev/null 2.39s user 0.01s system 99% cpu 2.394 total
Todo
- Add
#o, #b, #x,#e, #i numerical prefixes - Add rational numbers to numerical tower
- Improve environment support
- Add to test cases