This is a Lisp dialect with the intention of establishing important modern features into the greatness that is Lisp.

Function Conventions

While there is no rule for it, certain patterns for naming functions are well-established in Coda.

null?PredicateDetermine if the parameter(s) fulfill some kind of condition, in this case an empty list.
set!DestructiveStore a new value in the place of an older one; in this case set a variable to a value, discarding the old one.
<array>ConstructorMake a new instance of an object, in this case an array.
char->intConversionConvert some value into another, usually of a different type; this example would give the Unicode codepoint of the given character.
func'Secondary / RecursiveSometimes it's useful to define a secondary or recursive function, while using the primary as an interface which accesses the secondary internally. The convention is to name the secondary with a prime.

Special Variables

Unlike Common Lisp, and taking some hints from Scheme and Clojure, Coda uses special values for truth and falsehood, namely #t and #f. The special forms for branching, like IF and COND, as well as any function that requires a predicate, such as FILTER, must evaluate either #t or #f -- no other value will cut it. Similarly, nil is now a special value that represents, well, nothing. It is not the same as the empty list '(). The semantics of many of the list functions are unaffected, e.g. (cdr (list "LISP")) => '() because (list "LISP") = (cons "LISP" '()).

Let's get rid of EQ, EQL, EQUAL, =, char=, string=, ...

There are too many equality functions in Lisp. Instead, normal functions will be overloaded like using CLOS-like techniques; this also creates an illusion of "type classes" like in Haskell. It would work something like the following:

(defgeneric :string (= s1 s2)
  (and (= (length s1) (length s2))
       (all (dotimes (length s1) (λ (x) (= (subseq s1 x) (subseq s2 x)))))))

Unfortunately, this slows down evaluation when the type of the the first argument cannot be inferred at compile-time. But I think it's worth it to avoid the 3,720 different equality functions currently in use.