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925 lines
31 KiB
Plaintext
925 lines
31 KiB
Plaintext
;; Haskell 98 expression parser.
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;;
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;; Input: the post-layout token list from (hk-layout (hk-tokenize src)).
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;; Output: an AST. Nodes are plain lists tagged by a keyword head
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;; (keywords evaluate to their string name, so `(list :var "x")` is
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;; indistinguishable from `(list "var" "x")` at runtime — this lets
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;; tests literally write `(list :var "x")` on both sides).
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;;
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;; Scope (this iteration — expressions only):
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;; atoms int/float/string/char/var/con, parens, tuple, list, range
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;; application left-associative, f x y z
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;; prefix - unary negation on an lexp
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;; infix ops precedence-climbing, full Haskell 98 default table
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;; lambda \x y -> body
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;; if if c then t else e
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;; let let { x = e ; y = e } in body (uses layout braces)
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;;
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;; AST shapes:
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;; (:int N)
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;; (:float F)
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;; (:string S)
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;; (:char C)
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;; (:var NAME)
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;; (:con NAME)
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;; (:app FN ARG) — binary, chain for multi-arg
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;; (:op OP LHS RHS) — binary infix
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;; (:neg E)
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;; (:tuple ITEMS) — ITEMS is a list of AST nodes
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;; (:list ITEMS) — enumerated list
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;; (:range FROM TO) — [from..to]
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;; (:range-step FROM NEXT TO) — [from,next..to]
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;; (:if C T E)
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;; (:lambda PARAMS BODY) — PARAMS is list of varids
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;; (:let BINDS BODY) — BINDS is list of (:bind NAME EXPR)
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;; ── Operator precedence table (Haskell 98 defaults) ──────────────
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(define
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hk-op-prec-table
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(let
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((t (dict)))
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(dict-set! t "!!" {:prec 9 :assoc "left"})
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(dict-set! t "." {:prec 9 :assoc "right"})
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(dict-set! t "^" {:prec 8 :assoc "right"})
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(dict-set! t "^^" {:prec 8 :assoc "right"})
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(dict-set! t "**" {:prec 8 :assoc "right"})
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(dict-set! t "*" {:prec 7 :assoc "left"})
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(dict-set! t "/" {:prec 7 :assoc "left"})
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(dict-set! t "+" {:prec 6 :assoc "left"})
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(dict-set! t "-" {:prec 6 :assoc "left"})
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(dict-set! t ":" {:prec 5 :assoc "right"})
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(dict-set! t "++" {:prec 5 :assoc "right"})
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(dict-set! t "==" {:prec 4 :assoc "non"})
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(dict-set! t "/=" {:prec 4 :assoc "non"})
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(dict-set! t "<" {:prec 4 :assoc "non"})
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(dict-set! t "<=" {:prec 4 :assoc "non"})
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(dict-set! t ">" {:prec 4 :assoc "non"})
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(dict-set! t ">=" {:prec 4 :assoc "non"})
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(dict-set! t "&&" {:prec 3 :assoc "right"})
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(dict-set! t "||" {:prec 2 :assoc "right"})
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(dict-set! t ">>" {:prec 1 :assoc "left"})
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(dict-set! t ">>=" {:prec 1 :assoc "left"})
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(dict-set! t "=<<" {:prec 1 :assoc "right"})
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(dict-set! t "$" {:prec 0 :assoc "right"})
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(dict-set! t "$!" {:prec 0 :assoc "right"})
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t))
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(define
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hk-op-info
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(fn
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(op)
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(if
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(has-key? hk-op-prec-table op)
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(get hk-op-prec-table op)
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{:prec 9 :assoc "left"})))
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;; ── Atom-start predicate ─────────────────────────────────────────
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(define
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hk-atom-start?
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(fn
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(tok)
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(if
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(nil? tok)
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false
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(let
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((ty (get tok "type")))
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(or
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(= ty "integer")
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(= ty "float")
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(= ty "string")
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(= ty "char")
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(= ty "varid")
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(= ty "conid")
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(= ty "qvarid")
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(= ty "qconid")
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(= ty "lparen")
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(= ty "lbracket"))))))
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;; apat-start? — what can begin an atomic pattern
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(define
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hk-apat-start?
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(fn
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(tok)
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(if
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(nil? tok)
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false
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(let
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((ty (get tok "type")) (val (get tok "value")))
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(or
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(and (= ty "reserved") (= val "_"))
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(= ty "integer")
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(= ty "float")
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(= ty "string")
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(= ty "char")
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(= ty "varid")
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(= ty "conid")
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(= ty "qconid")
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(= ty "lparen")
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(= ty "lbracket")
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(and (= ty "varsym") (= val "-"))
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(and (= ty "reservedop") (= val "~")))))))
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;; ── Main entry ───────────────────────────────────────────────────
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(define
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hk-parse-expr
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(fn
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(tokens)
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(let
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((toks tokens) (pos 0) (n (len tokens)))
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(define hk-peek (fn () (if (< pos n) (nth toks pos) nil)))
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(define
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hk-peek-at
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(fn
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(offset)
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(if (< (+ pos offset) n) (nth toks (+ pos offset)) nil)))
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(define
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hk-advance!
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(fn () (let ((t (hk-peek))) (set! pos (+ pos 1)) t)))
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(define
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hk-peek-type
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(fn () (let ((t (hk-peek))) (if (nil? t) "<eof>" (get t "type")))))
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(define
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hk-peek-value
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(fn () (let ((t (hk-peek))) (if (nil? t) nil (get t "value")))))
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(define
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hk-match?
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(fn
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(ty v)
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(let
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((t (hk-peek)))
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(and
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(not (nil? t))
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(= (get t "type") ty)
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(or (nil? v) (= (get t "value") v))))))
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(define
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hk-err
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(fn
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(msg)
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(raise
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(str
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"parse error: "
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msg
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" (at "
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(hk-peek-type)
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(if (nil? (hk-peek-value)) "" (str " " (hk-peek-value)))
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")"))))
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(define
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hk-expect!
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(fn
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(ty v)
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(if
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(hk-match? ty v)
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(hk-advance!)
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(hk-err
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(str "expected " ty (if (nil? v) "" (str " '" v "'")))))))
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;; ── Atoms ────────────────────────────────────────────────
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(define
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hk-parse-aexp
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(fn
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()
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(let
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((t (hk-peek)))
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(cond
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((nil? t) (hk-err "unexpected end of input"))
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((= (get t "type") "integer")
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(do (hk-advance!) (list :int (get t "value"))))
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((= (get t "type") "float")
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(do (hk-advance!) (list :float (get t "value"))))
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((= (get t "type") "string")
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(do (hk-advance!) (list :string (get t "value"))))
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((= (get t "type") "char")
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(do (hk-advance!) (list :char (get t "value"))))
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((= (get t "type") "varid")
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(do (hk-advance!) (list :var (get t "value"))))
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((= (get t "type") "conid")
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(do (hk-advance!) (list :con (get t "value"))))
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((= (get t "type") "qvarid")
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(do (hk-advance!) (list :var (get t "value"))))
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((= (get t "type") "qconid")
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(do (hk-advance!) (list :con (get t "value"))))
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((= (get t "type") "lparen") (hk-parse-parens))
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((= (get t "type") "lbracket") (hk-parse-list-lit))
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(:else (hk-err "unexpected token in expression"))))))
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;; ── Parens / tuple / unit ────────────────────────────────
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(define
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hk-parse-parens
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(fn
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()
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(hk-expect! "lparen" nil)
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(cond
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((hk-match? "rparen" nil)
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(do (hk-advance!) (list :con "()")))
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(:else
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(let
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((first-e (hk-parse-expr-inner))
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(items (list))
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(is-tuple false))
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(append! items first-e)
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(define
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hk-tup-loop
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(fn
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()
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(when
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(hk-match? "comma" nil)
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(do
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(hk-advance!)
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(set! is-tuple true)
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(append! items (hk-parse-expr-inner))
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(hk-tup-loop)))))
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(hk-tup-loop)
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(hk-expect! "rparen" nil)
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(if is-tuple (list :tuple items) first-e))))))
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;; ── List literal / range ─────────────────────────────────
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(define
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hk-parse-list-lit
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(fn
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()
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(hk-expect! "lbracket" nil)
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(cond
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((hk-match? "rbracket" nil)
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(do (hk-advance!) (list :list (list))))
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(:else
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(let
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((first-e (hk-parse-expr-inner)))
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(cond
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((hk-match? "reservedop" "..")
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(do
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(hk-advance!)
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(let
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((end-e (hk-parse-expr-inner)))
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(hk-expect! "rbracket" nil)
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(list :range first-e end-e))))
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((hk-match? "comma" nil)
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(do
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(hk-advance!)
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(let
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((second-e (hk-parse-expr-inner)))
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(cond
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((hk-match? "reservedop" "..")
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(do
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(hk-advance!)
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(let
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((end-e (hk-parse-expr-inner)))
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(hk-expect! "rbracket" nil)
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(list
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:range-step
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first-e
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second-e
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end-e))))
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(:else
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(let
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((items (list)))
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(append! items first-e)
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(append! items second-e)
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(define
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hk-list-loop
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(fn
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()
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(when
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(hk-match? "comma" nil)
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(do
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(hk-advance!)
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(append!
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items
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(hk-parse-expr-inner))
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(hk-list-loop)))))
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(hk-list-loop)
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(hk-expect! "rbracket" nil)
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(list :list items)))))))
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(:else
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(do
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(hk-expect! "rbracket" nil)
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(list :list (list first-e))))))))))
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;; ── Application: left-assoc aexp chain ───────────────────
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(define
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hk-parse-fexp
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(fn
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()
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(let
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((fn-e (hk-parse-aexp)))
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(define
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hk-app-loop
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(fn
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()
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(when
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(hk-atom-start? (hk-peek))
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(let
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((arg (hk-parse-aexp)))
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(set! fn-e (list :app fn-e arg))
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(hk-app-loop)))))
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(hk-app-loop)
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fn-e)))
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;; ── Lambda: \ apat1 apat2 ... apatn -> body ──────────────
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(define
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hk-parse-lambda
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(fn
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()
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(hk-expect! "reservedop" "\\")
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(let
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((params (list)))
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(when
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(not (hk-apat-start? (hk-peek)))
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(hk-err "lambda needs at least one pattern parameter"))
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(define
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hk-lam-loop
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(fn
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()
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(when
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(hk-apat-start? (hk-peek))
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(do
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(append! params (hk-parse-apat))
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(hk-lam-loop)))))
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(hk-lam-loop)
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(hk-expect! "reservedop" "->")
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(list :lambda params (hk-parse-expr-inner)))))
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;; ── if-then-else ────────────────────────────────────────
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(define
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hk-parse-if
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(fn
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()
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(hk-expect! "reserved" "if")
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(let
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((c (hk-parse-expr-inner)))
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(hk-expect! "reserved" "then")
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(let
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((th (hk-parse-expr-inner)))
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(hk-expect! "reserved" "else")
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(let
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((el (hk-parse-expr-inner)))
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(list :if c th el))))))
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;; ── Let expression ──────────────────────────────────────
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(define
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hk-parse-let
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(fn
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()
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(hk-expect! "reserved" "let")
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(let ((explicit (hk-match? "lbrace" nil)))
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(if
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explicit
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(hk-advance!)
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(hk-expect! "vlbrace" nil))
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(let
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((binds (list)))
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(when
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(not
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(if
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explicit
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(hk-match? "rbrace" nil)
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(hk-match? "vrbrace" nil)))
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(do
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(append! binds (hk-parse-bind))
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(define
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hk-let-loop
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(fn
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()
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(when
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(or
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(hk-match? "semi" nil)
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(hk-match? "vsemi" nil))
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(do
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(hk-advance!)
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(when
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(not
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(if
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explicit
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(hk-match? "rbrace" nil)
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(hk-match? "vrbrace" nil)))
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(append! binds (hk-parse-bind)))
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(hk-let-loop)))))
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(hk-let-loop)))
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(if
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explicit
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(hk-expect! "rbrace" nil)
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(hk-expect! "vrbrace" nil))
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(hk-expect! "reserved" "in")
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(list :let binds (hk-parse-expr-inner))))))
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;; Binding LHS is a pattern. Simple `x = e` parses as
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;; (:bind (:p-var "x") e); pattern bindings like
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;; `(x, y) = pair` parse with a p-tuple LHS.
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(define
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hk-parse-bind
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(fn
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()
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(let
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((pat (hk-parse-pat)))
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(hk-expect! "reservedop" "=")
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(list :bind pat (hk-parse-expr-inner)))))
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;; ── Patterns ─────────────────────────────────────────────
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(define
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hk-parse-apat
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(fn
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()
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(let
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((t (hk-peek)))
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(cond
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((nil? t) (hk-err "unexpected end of input in pattern"))
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((and
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(= (get t "type") "reserved")
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(= (get t "value") "_"))
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(do (hk-advance!) (list :p-wild)))
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((and
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(= (get t "type") "reservedop")
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(= (get t "value") "~"))
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(do (hk-advance!) (list :p-lazy (hk-parse-apat))))
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((and
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(= (get t "type") "varsym")
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(= (get t "value") "-"))
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(do
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(hk-advance!)
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(let
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((n (hk-peek)))
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(cond
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((nil? n)
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(hk-err "expected numeric literal after '-'"))
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((= (get n "type") "integer")
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(do
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(hk-advance!)
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(list :p-int (- 0 (get n "value")))))
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((= (get n "type") "float")
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(do
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(hk-advance!)
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(list :p-float (- 0 (get n "value")))))
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(:else
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(hk-err
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"only numeric literals may follow '-' in a pattern"))))))
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((= (get t "type") "integer")
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(do (hk-advance!) (list :p-int (get t "value"))))
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((= (get t "type") "float")
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(do (hk-advance!) (list :p-float (get t "value"))))
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((= (get t "type") "string")
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(do (hk-advance!) (list :p-string (get t "value"))))
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((= (get t "type") "char")
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(do (hk-advance!) (list :p-char (get t "value"))))
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((= (get t "type") "varid")
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(let
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((next-t (hk-peek-at 1)))
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(cond
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((and
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(not (nil? next-t))
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(= (get next-t "type") "reservedop")
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(= (get next-t "value") "@"))
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(do
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(hk-advance!)
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(hk-advance!)
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(list :p-as (get t "value") (hk-parse-apat))))
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(:else
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(do (hk-advance!) (list :p-var (get t "value")))))))
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((= (get t "type") "conid")
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(do
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(hk-advance!)
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(list :p-con (get t "value") (list))))
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((= (get t "type") "qconid")
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(do
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(hk-advance!)
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(list :p-con (get t "value") (list))))
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((= (get t "type") "lparen") (hk-parse-paren-pat))
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((= (get t "type") "lbracket") (hk-parse-list-pat))
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(:else (hk-err "unexpected token in pattern"))))))
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(define
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hk-parse-paren-pat
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(fn
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()
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(hk-expect! "lparen" nil)
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(cond
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((hk-match? "rparen" nil)
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(do (hk-advance!) (list :p-con "()" (list))))
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(:else
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(let
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((first-p (hk-parse-pat))
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(items (list))
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(is-tup false))
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(append! items first-p)
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(define
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hk-ppt-loop
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(fn
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()
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(when
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(hk-match? "comma" nil)
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(do
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(hk-advance!)
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(set! is-tup true)
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(append! items (hk-parse-pat))
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(hk-ppt-loop)))))
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(hk-ppt-loop)
|
|
(hk-expect! "rparen" nil)
|
|
(if is-tup (list :p-tuple items) first-p))))))
|
|
|
|
(define
|
|
hk-parse-list-pat
|
|
(fn
|
|
()
|
|
(hk-expect! "lbracket" nil)
|
|
(cond
|
|
((hk-match? "rbracket" nil)
|
|
(do (hk-advance!) (list :p-list (list))))
|
|
(:else
|
|
(let
|
|
((items (list)))
|
|
(append! items (hk-parse-pat))
|
|
(define
|
|
hk-plt-loop
|
|
(fn
|
|
()
|
|
(when
|
|
(hk-match? "comma" nil)
|
|
(do
|
|
(hk-advance!)
|
|
(append! items (hk-parse-pat))
|
|
(hk-plt-loop)))))
|
|
(hk-plt-loop)
|
|
(hk-expect! "rbracket" nil)
|
|
(list :p-list items))))))
|
|
|
|
(define
|
|
hk-parse-pat-lhs
|
|
(fn
|
|
()
|
|
(let
|
|
((t (hk-peek)))
|
|
(cond
|
|
((and
|
|
(not (nil? t))
|
|
(or
|
|
(= (get t "type") "conid")
|
|
(= (get t "type") "qconid")))
|
|
(let
|
|
((name (get (hk-advance!) "value")) (args (list)))
|
|
(define
|
|
hk-pca-loop
|
|
(fn
|
|
()
|
|
(when
|
|
(hk-apat-start? (hk-peek))
|
|
(do
|
|
(append! args (hk-parse-apat))
|
|
(hk-pca-loop)))))
|
|
(hk-pca-loop)
|
|
(list :p-con name args)))
|
|
(:else (hk-parse-apat))))))
|
|
|
|
;; Infix constructor patterns: `x : xs`, `a `Cons` b`, etc.
|
|
;; Right-associative, single precedence band.
|
|
(define
|
|
hk-parse-pat
|
|
(fn
|
|
()
|
|
(let
|
|
((left (hk-parse-pat-lhs)))
|
|
(cond
|
|
((or
|
|
(= (hk-peek-type) "consym")
|
|
(and
|
|
(= (hk-peek-type) "reservedop")
|
|
(= (hk-peek-value) ":")))
|
|
(let
|
|
((op (get (hk-advance!) "value")))
|
|
(let
|
|
((right (hk-parse-pat)))
|
|
(list :p-con op (list left right)))))
|
|
(:else left)))))
|
|
|
|
;; ── case ─ of { pat -> expr ; ... } ─────────────────────
|
|
(define
|
|
hk-parse-alt
|
|
(fn
|
|
()
|
|
(let
|
|
((pat (hk-parse-pat)))
|
|
(hk-expect! "reservedop" "->")
|
|
(list :alt pat (hk-parse-expr-inner)))))
|
|
|
|
(define
|
|
hk-parse-case
|
|
(fn
|
|
()
|
|
(hk-expect! "reserved" "case")
|
|
(let
|
|
((scrut (hk-parse-expr-inner)))
|
|
(hk-expect! "reserved" "of")
|
|
(let
|
|
((explicit (hk-match? "lbrace" nil)))
|
|
(if
|
|
explicit
|
|
(hk-advance!)
|
|
(hk-expect! "vlbrace" nil))
|
|
(let
|
|
((alts (list)))
|
|
(when
|
|
(not
|
|
(if
|
|
explicit
|
|
(hk-match? "rbrace" nil)
|
|
(hk-match? "vrbrace" nil)))
|
|
(do
|
|
(append! alts (hk-parse-alt))
|
|
(define
|
|
hk-case-loop
|
|
(fn
|
|
()
|
|
(when
|
|
(or
|
|
(hk-match? "semi" nil)
|
|
(hk-match? "vsemi" nil))
|
|
(do
|
|
(hk-advance!)
|
|
(when
|
|
(not
|
|
(if
|
|
explicit
|
|
(hk-match? "rbrace" nil)
|
|
(hk-match? "vrbrace" nil)))
|
|
(append! alts (hk-parse-alt)))
|
|
(hk-case-loop)))))
|
|
(hk-case-loop)))
|
|
(if
|
|
explicit
|
|
(hk-expect! "rbrace" nil)
|
|
(hk-expect! "vrbrace" nil))
|
|
(list :case scrut alts))))))
|
|
|
|
;; ── do { stmt ; stmt ; ... } ────────────────────────────
|
|
;; Scan ahead (respecting paren/bracket/brace depth) for a `<-`
|
|
;; before the next `;` / `}` — distinguishes `pat <- e` from a
|
|
;; bare expression statement.
|
|
(define
|
|
hk-do-stmt-is-bind?
|
|
(fn
|
|
()
|
|
(let
|
|
((j pos) (depth 0) (found false) (done false))
|
|
(define
|
|
hk-scan-loop
|
|
(fn
|
|
()
|
|
(when
|
|
(and (not done) (< j n))
|
|
(let
|
|
((t (nth toks j)) (ty nil))
|
|
(set! ty (get t "type"))
|
|
(cond
|
|
((and
|
|
(= depth 0)
|
|
(or
|
|
(= ty "semi")
|
|
(= ty "vsemi")
|
|
(= ty "rbrace")
|
|
(= ty "vrbrace")))
|
|
(set! done true))
|
|
((and
|
|
(= depth 0)
|
|
(= ty "reservedop")
|
|
(= (get t "value") "<-"))
|
|
(do (set! found true) (set! done true)))
|
|
((or
|
|
(= ty "lparen")
|
|
(= ty "lbracket")
|
|
(= ty "lbrace")
|
|
(= ty "vlbrace"))
|
|
(set! depth (+ depth 1)))
|
|
((or
|
|
(= ty "rparen")
|
|
(= ty "rbracket"))
|
|
(set! depth (- depth 1)))
|
|
(:else nil))
|
|
(set! j (+ j 1))
|
|
(hk-scan-loop)))))
|
|
(hk-scan-loop)
|
|
found)))
|
|
|
|
(define
|
|
hk-parse-do-let
|
|
(fn
|
|
()
|
|
(hk-expect! "reserved" "let")
|
|
(let ((explicit (hk-match? "lbrace" nil)))
|
|
(if
|
|
explicit
|
|
(hk-advance!)
|
|
(hk-expect! "vlbrace" nil))
|
|
(let
|
|
((binds (list)))
|
|
(when
|
|
(not
|
|
(if
|
|
explicit
|
|
(hk-match? "rbrace" nil)
|
|
(hk-match? "vrbrace" nil)))
|
|
(do
|
|
(append! binds (hk-parse-bind))
|
|
(define
|
|
hk-dlet-loop
|
|
(fn
|
|
()
|
|
(when
|
|
(or
|
|
(hk-match? "semi" nil)
|
|
(hk-match? "vsemi" nil))
|
|
(do
|
|
(hk-advance!)
|
|
(when
|
|
(not
|
|
(if
|
|
explicit
|
|
(hk-match? "rbrace" nil)
|
|
(hk-match? "vrbrace" nil)))
|
|
(append! binds (hk-parse-bind)))
|
|
(hk-dlet-loop)))))
|
|
(hk-dlet-loop)))
|
|
(if
|
|
explicit
|
|
(hk-expect! "rbrace" nil)
|
|
(hk-expect! "vrbrace" nil))
|
|
(list :do-let binds)))))
|
|
|
|
(define
|
|
hk-parse-do-stmt
|
|
(fn
|
|
()
|
|
(cond
|
|
((hk-match? "reserved" "let") (hk-parse-do-let))
|
|
((hk-do-stmt-is-bind?)
|
|
(let
|
|
((pat (hk-parse-pat)))
|
|
(hk-expect! "reservedop" "<-")
|
|
(list :do-bind pat (hk-parse-expr-inner))))
|
|
(:else (list :do-expr (hk-parse-expr-inner))))))
|
|
|
|
(define
|
|
hk-parse-do
|
|
(fn
|
|
()
|
|
(hk-expect! "reserved" "do")
|
|
(let
|
|
((explicit (hk-match? "lbrace" nil)))
|
|
(if
|
|
explicit
|
|
(hk-advance!)
|
|
(hk-expect! "vlbrace" nil))
|
|
(let
|
|
((stmts (list)))
|
|
(when
|
|
(not
|
|
(if
|
|
explicit
|
|
(hk-match? "rbrace" nil)
|
|
(hk-match? "vrbrace" nil)))
|
|
(do
|
|
(append! stmts (hk-parse-do-stmt))
|
|
(define
|
|
hk-do-loop
|
|
(fn
|
|
()
|
|
(when
|
|
(or
|
|
(hk-match? "semi" nil)
|
|
(hk-match? "vsemi" nil))
|
|
(do
|
|
(hk-advance!)
|
|
(when
|
|
(not
|
|
(if
|
|
explicit
|
|
(hk-match? "rbrace" nil)
|
|
(hk-match? "vrbrace" nil)))
|
|
(append! stmts (hk-parse-do-stmt)))
|
|
(hk-do-loop)))))
|
|
(hk-do-loop)))
|
|
(if
|
|
explicit
|
|
(hk-expect! "rbrace" nil)
|
|
(hk-expect! "vrbrace" nil))
|
|
(list :do stmts)))))
|
|
|
|
;; ── lexp: lambda | if | let | case | do | fexp ──────────
|
|
(define
|
|
hk-parse-lexp
|
|
(fn
|
|
()
|
|
(cond
|
|
((hk-match? "reservedop" "\\") (hk-parse-lambda))
|
|
((hk-match? "reserved" "if") (hk-parse-if))
|
|
((hk-match? "reserved" "let") (hk-parse-let))
|
|
((hk-match? "reserved" "case") (hk-parse-case))
|
|
((hk-match? "reserved" "do") (hk-parse-do))
|
|
(:else (hk-parse-fexp)))))
|
|
|
|
;; ── Prefix: unary - ─────────────────────────────────────
|
|
(define
|
|
hk-parse-prefix
|
|
(fn
|
|
()
|
|
(cond
|
|
((and (hk-match? "varsym" "-"))
|
|
(do (hk-advance!) (list :neg (hk-parse-lexp))))
|
|
(:else (hk-parse-lexp)))))
|
|
|
|
;; ── Infix: precedence climbing ──────────────────────────
|
|
(define
|
|
hk-is-infix-op?
|
|
(fn
|
|
(tok)
|
|
(if
|
|
(nil? tok)
|
|
false
|
|
(or
|
|
(= (get tok "type") "varsym")
|
|
(= (get tok "type") "consym")
|
|
(and
|
|
(= (get tok "type") "reservedop")
|
|
(= (get tok "value") ":"))
|
|
(= (get tok "type") "backtick")))))
|
|
|
|
(define
|
|
hk-consume-op!
|
|
(fn
|
|
()
|
|
(let
|
|
((t (hk-peek)))
|
|
(cond
|
|
((= (get t "type") "backtick")
|
|
(do
|
|
(hk-advance!)
|
|
(let
|
|
((v (hk-expect! "varid" nil)))
|
|
(hk-expect! "backtick" nil)
|
|
(get v "value"))))
|
|
(:else (do (hk-advance!) (get t "value")))))))
|
|
|
|
(define
|
|
hk-parse-infix
|
|
(fn
|
|
(min-prec)
|
|
(let
|
|
((left (hk-parse-prefix)))
|
|
(define
|
|
hk-inf-loop
|
|
(fn
|
|
()
|
|
(when
|
|
(hk-is-infix-op? (hk-peek))
|
|
(let
|
|
((op-tok (hk-peek)))
|
|
(let
|
|
((op-name
|
|
(if
|
|
(= (get op-tok "type") "backtick")
|
|
(get (hk-peek-at 1) "value")
|
|
(get op-tok "value"))))
|
|
(let
|
|
((info (hk-op-info op-name)))
|
|
(when
|
|
(>= (get info "prec") min-prec)
|
|
(do
|
|
(hk-consume-op!)
|
|
(let
|
|
((next-min
|
|
(cond
|
|
((= (get info "assoc") "left")
|
|
(+ (get info "prec") 1))
|
|
((= (get info "assoc") "right")
|
|
(get info "prec"))
|
|
(:else (+ (get info "prec") 1)))))
|
|
(let
|
|
((right (hk-parse-infix next-min)))
|
|
(set!
|
|
left
|
|
(list :op op-name left right))
|
|
(hk-inf-loop)))))))))))
|
|
(hk-inf-loop)
|
|
left)))
|
|
|
|
(define hk-parse-expr-inner (fn () (hk-parse-infix 0)))
|
|
|
|
;; ── Top-level: strip leading/trailing module-level braces ─
|
|
(let
|
|
((start-brace
|
|
(or
|
|
(hk-match? "vlbrace" nil)
|
|
(hk-match? "lbrace" nil))))
|
|
(when start-brace (hk-advance!))
|
|
(let
|
|
((result (hk-parse-expr-inner)))
|
|
(when start-brace
|
|
(when
|
|
(or
|
|
(hk-match? "vrbrace" nil)
|
|
(hk-match? "rbrace" nil))
|
|
(hk-advance!)))
|
|
result)))))
|
|
|
|
;; ── Convenience: tokenize + layout + parse ───────────────────────
|
|
(define
|
|
hk-parse
|
|
(fn (src) (hk-parse-expr (hk-layout (hk-tokenize src)))))
|