Catgirls-With-Keyboards/lispnt

Lisp written by catgirls who don't know lisp.

Lispn't

Lisp written by catgirls who don't know lisp.

Basics

Lispn't replaces list based s-expressions with curry based thunks, which are stored as compositions ($) of atoms (:atom). For example here is the structure of (:true :x :y):

$
    $
        :true
        :x
    :y

This is important as every single behaviour in Lispn't is defined - in some scope - in terms of pattern matching on thunks:

{
    :true a b = a;
    :false a b = b;
}

Because expressions are lazy evaluated, and behaviour definitions appear in scopes, atoms also carry where they were written so that thunk evaluation is predictable.

Evaluation

Scopes will shadow the behaviours of their parent scopes and behaviours will be interpreted first to last. Here is an example to deponstrate this concept:

:f x = :third;

:g x = {
    :f (:succ (:succ x)) = :first;
    :f (:succ x) = :second;
} :f x;

In reality a thunk is not just a single object, but a list of successively reduced expressions. (given that thunk evaluation is context independent, this is well defined):

$
    $
        $
            :id
            :true
        :x
    :y
# =>
$
    $
        :true
        :x
    :y
# =>
:x

When reducing a thunk, the callers behaviour is used to try and find a pattern to match.

The following behaviour is not finalised as the neuance of its implimentation has huge implications on performance:

• If this does not succeed then the caller is successively reduced, each time a reavaulation is attempted.
• If this process fails then the argument is successivelt reduces, each time each caller is retried in order.
• If all combinations of partially reduced caller and argument fails then the reduction fails and the thunk cannot be reduced further.