hk-bind-exceptions! in eval.sx registers throwIO, throw, evaluate, catch,
try, handle, displayException. SomeException constructor pre-registered
in runtime.sx (arity 1, type SomeException).
throwIO and the existing error primitive both raise via SX `raise` with a
uniform "hk-error: msg" string. catch/try/handle parse it back into a
SomeException via hk-exception-of, which strips nested
'Unhandled exception: "..."' host wraps (CEK's host_error formatter) and
the "hk-error: " prefix.
catch and handle evaluate the handler outside the guard scope (build an
"ok"/"exn" outcome tag inside guard, then dispatch outside) so that a
re-throw from the handler propagates past this catch — matching Haskell
semantics rather than infinite-looping in the same guard.
14 unit tests in tests/exceptions.sx (catch success, catch error, try
Right/Left, handle, throwIO + catch/try, evaluate, nested catch, do-bind
through catch, branch on try result, IORef-mutating handler).
Conformance: safediv.hs (8/8) and trycatch.hs (8/8). Scoreboard now
285/285 tests, 36/36 programs.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Haskell strings are [Char]. Calling reverse / head / length on a SX raw
string transparently produces a cons-list of char codes (via hk-str-head /
hk-str-tail in runtime.sx), but (==) then compared the original raw string
against the char-code cons-list and always returned False — so
"racecar" == reverse "racecar" was False.
Added hk-try-charlist-to-string and hk-normalize-for-eq in eval.sx; routed
== and /= through hk-normalize-for-eq so a string compares equal to any
cons-list whose elements are valid Unicode code points spelling the same
characters, and "[]" ↔ "".
palindrome.hs lifts from 9/12 → 12/12; conformance 33/34 → 34/34 programs,
266/269 → 269/269 tests.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
hk-bind-data-ioref! registers newIORef / readIORef / writeIORef /
modifyIORef / modifyIORef' under the import alias (default IORef).
Representation: dict {"hk-ioref" true "hk-value" v} allocated inside IO.
modifyIORef' uses hk-deep-force on the new value before write.
Side-effect: fixed pre-existing bug in import handler — modname was
reading (nth d 1) (the qualified flag) instead of (nth d 2). All
'import qualified … as Foo' paths were silently no-ops; map.sx unit
suite jumps from 22→26 passing.
Conformance now 33/34 programs, 266/269 tests (only pre-existing
palindrome.hs 9/12 still failing on string-as-list reversal, present
on prior commit).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
