(Note, some of these are possibly long-term plans.)
Just as we have defined fun in terms of fexprs, we can
define macro in terms of fexprs. (It is expected to
return a literal chunk of program, which we then evaluate.)
It would just be a fexpr that evaluates (in the calling environment) what the body evaluates to.
Insofar as the types of Robin are disjoint, we can have a
typeof intrinsic which returns a literal symbol such as
number, list, and so forth, instead of n predicates.
In practice the predicates are useful, and would be retained
in the stdlib. But this could make the set of intrinsics smaller.
Values of "opaque" type. Intrinsics wrap and unwrap. But note
that only the functions implementing the ADT are guaranteed to be able
to unwrap an opaque value, and those functions might be implemented
natively, rather than as Robin code that uses wrap and unwrap.
Then, can we provide environments as an abstract type? We would
also provide env->alist and alist->env so they can be worked
with easily. But they could be used natively to support symbol
lookup, and if they are implemented as trees or hash tables, this
might have performance benefits. (Or perhaps not.)
Opaque type might also be useful for internals, e.g. signaling to runtime system that an error occurred.
(compose f1 f2) to compose two operators.
(modulo x y) which is always positive, change remainder to
be sign of divisor (like R6RS.)
let and choose follow the same pattern. Consider a general
chain combinator such that (chain bind (...) ...) is let and
(chain if (...) ...) is choose.
lispish lib, that just gives you all the old jargon-y names
as aliases.
rename form.
Some way to make it easier to test reactive programs, i.e. some way to provide mock facilities. (Actually, do we need this? Or rather, how reactor-specific is this? You can just test the transducer itself, feeding it a set of mock events.)
The QuickCheck tests for equivalency don't seem to be very strong. They might even be outright wrong. Generally, lots and lots more could be done with the QuickCheck tests.
Finish the tutorial (recursive fexprs, advanced usage of reactors).
Perhaps namespace each event name.
A more involved environment, with more facilities than just
line-terminal. Multiplexed I/O would be a start, could write an
IRC client. Could also define an environment for web pages.
For that matter, HasteMain.hs should inject facilities that
only make sense in the HTML5 DOM.
Subscription and unsubscription from facilities using standard commands.
More elegant way for handling abort responses (they should not trigger events -- because this can lead to a cascade of abort responses, if the reactor is erroneously handling those events too -- but they should be displayed if requested.)
Allow only one reactor. (Its transducer can be composed from multiple operators, instead of having multiple reactors.)
Hunt the Wumpus.
Implementation of a concatenative language in an idiomatic style,
taking a list like (1 2 + 3 *) and folding compose over it to
obtain a function, and applying that function.
Rename "small" to "base".
Rename fun to function. This is because Robin prefers full words
over abbreviations, which are jargon-y.