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Parser.mly
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Parser.mly
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%token<string> IDENT
%token<string> UIDENT
%token<int> INTLITERAL
%token FUN IN LET PRINT REC
%token IFZERO THEN ELSE
%token ARROW EQ LPAREN RPAREN BAR COMMA STAR SEMISEMI COLON QUOTE ARROWOPEN ARROWCLOSE LBRACK RBRACK BANG
%token TYPE OF EFFECT
%token MATCH WITH
%token<RawLambda.binop> MULOP ADDOP
%token EOF
%nonassoc IN
%nonassoc WITH
%nonassoc below_EFFECT
%nonassoc EFFECT
%left BAR
(* %left COMMA *)
%right ARROW ARROWOPEN ARROWCLOSE
(* %nonassoc IFZERO *)
%nonassoc ELSE
%left ADDOP
%left MULOP STAR
%nonassoc prec_constant_constructor
(* First tokens of atomic_term *)
%nonassoc LPAREN UIDENT IDENT INTLITERAL
%start<RawLambda.program> entry
%{
open RawLambda
%}
%%
(* -------------------------------------------------------------------------- *)
(* A toplevel phrase is just a term. *)
entry:
p = program EOF { p }
program:
| t = any_term p = program_tail { { value = DTerm t ; place = t.place } :: p }
| p = program_tail { p }
program_tail:
| { [] }
| SEMISEMI p = program { p }
| d = decl p = program_tail { d :: p }
(* -------------------------------------------------------------------------- *)
(* The syntax of terms is stratified as follows:
atomic_term -- unambiguously delimited terms
application_term -- n-ary applications of atomic terms
any_term -- everything
*)
%inline decl:
| d = placed(decl_) { d }
type_var_decl:
| QUOTE i = IDENT { TTypeVar i }
| BANG i = IDENT { TEffectVar i }
type_decl_id:
| x = IDENT { [], x }
| v = type_var_decl x = IDENT { [v], x }
| LPAREN l = separated_nonempty_list(COMMA, type_var_decl) RPAREN x = IDENT
{ l, x }
decl_:
| LET mode = recursive x = IDENT EQ t = any_term
{ DLet (mode, x, t) }
| TYPE x = type_decl_id EQ l = left_flexible_list(BAR, placed(type_decl_case_))
{ DNewType (x, l) }
| TYPE x = type_decl_id EQ t = ty
{ DTypeSynonym (x, t) }
(*
| EFFECT x = IDENT EQ l = left_flexible_list(BAR, placed(effect_decl_case_))
{ DEffect (x, l) }
*)
| EFFECT x = IDENT EQ e = placed(effect_decl_case_)
{ DEffect (x, e) }
effect_decl_case_:
| c = UIDENT COLON t = ty
{
match t.value with
| TArrow (t1, _, t2) -> c, Some t1, t2
| _ -> c, None, t
}
type_decl_case_:
| c = UIDENT { (c, []) }
| c = UIDENT OF l = separated_list(STAR, simple_type) { (c, l) }
%inline simple_type:
| t = placed(simple_type_) { t }
%inline ty:
| t = placed(ty_) { t }
ty_:
| t = simple_type_ { t }
| t = simple_type STAR l = separated_nonempty_list(STAR, simple_type)
{ TTuple (t :: l) }
| t1 = ty pl = placed(ARROW) t2 = ty
{ TArrow (t1, { place = pl.place ; value = EEmpty }, t2) }
| t1 = ty ARROWOPEN e = eff ARROWCLOSE t2 = ty { TArrow (t1, e, t2) }
simple_type_:
| LPAREN t = ty_ RPAREN { t }
| x = IDENT { TConstructor ([], x) }
| QUOTE x = IDENT { TVariable x }
| t = simple_type x = IDENT { TConstructor ([TType t], x) }
| LBRACK e = eff RBRACK x = IDENT { TConstructor ([TEff e], x) }
| LPAREN t1 = ty_or_eff COMMA l = separated_nonempty_list(COMMA, ty_or_eff) RPAREN x = IDENT
{ TConstructor (t1 :: l, x) }
ty_or_eff:
| t = ty { TType t }
| LBRACK e = eff RBRACK { TEff e }
%inline eff:
| e = placed(eff_) { e }
eff_:
| (* empty *) { EEmpty }
| BANG i = IDENT { EVariable i }
| i = IDENT { EEff (i, EEmpty) }
| i = IDENT BAR e = eff_ { EEff (i, e) }
atomic_term_:
| LPAREN t = any_term_ RPAREN
{ t }
| x = IDENT
{ Var x }
| i = INTLITERAL
{ Lit i }
| x = UIDENT %prec prec_constant_constructor
{ Constructor (x, None) }
%inline atomic_term:
| t = placed(atomic_term_) { t }
application_term_:
| t = atomic_term_
{ t }
| t1 = application_term t2 = atomic_term
{ App (t1, t2) }
| PRINT t2 = atomic_term
{ Print t2 }
| x = UIDENT t2 = application_term
{ Constructor (x, Some t2) }
%inline application_term:
| t = placed(application_term_) { t }
%inline binop:
| op = MULOP { op }
| STAR { OpMul }
| op = ADDOP { op }
any_term_:
| t = application_term_ { t }
| t1 = any_term op = binop t2 = any_term { BinOp (t1, op, t2) }
| FUN x = IDENT ARROW t = any_term
{ Lam (x, t) }
| LET mode = recursive x = IDENT EQ t1 = any_term IN t2 = any_term
{ Let (mode, x, t1, t2) }
| IFZERO t1 = any_term THEN t2 = any_term ELSE t3 = any_term
{ IfZero (t1, t2, t3) }
| MATCH t1 = any_term WITH cases = match_cases
{ Match (t1, cases) }
| t = application_term COMMA l = separated_nonempty_list(COMMA, application_term)
{ Tuple (t :: l) }
%inline match_cases:
| l = match_cases_ { List.rev l }
match_cases_:
| (* empty *) %prec below_EFFECT
{ [] }
| x = match_case
{ [x] }
| xs = match_cases_ BAR x = match_case
{ x :: xs }
%inline any_term:
| t = placed(any_term_) { t }
match_case:
| p = pattern ARROW t = any_term
{ (Pattern p, t) }
| EFFECT c = placed(UIDENT) p = pattern k = IDENT ARROW t = any_term
{ (Effect (c, Some p, k), t) }
| EFFECT c = placed(UIDENT) k = IDENT ARROW t = any_term
{ (Effect (c, None, k), t) }
%inline pattern:
| p = placed(pattern_) { p }
pattern_:
| p1 = pattern BAR p2 = pattern { POr (p1, p2) }
| p = application_pattern COMMA l = separated_nonempty_list(COMMA, application_pattern)
{ PTuple (p :: l) }
| p = application_pattern_ { p }
%inline application_pattern:
| p = placed(application_pattern_) { p }
application_pattern_:
| x = UIDENT p = simple_pattern { PConstructor (x, Some p) }
| p = simple_pattern_ { p }
%inline simple_pattern:
| p = placed(simple_pattern_) { p }
simple_pattern_:
| LPAREN p = pattern_ RPAREN { p }
| x = IDENT { PVar x }
| x = UIDENT { PConstructor (x, None) } %prec prec_constant_constructor
(* | x = UIDENT p = ioption(simple_pattern) { PConstructor (x, p) } *)
(* -------------------------------------------------------------------------- *)
(* A [let] construct carries an optional [rec] annotation. *)
recursive:
| REC { Recursive }
| { NonRecursive }
(* -------------------------------------------------------------------------- *)
(* A term is annotated with its start and end positions, for use in error
messages. *)
%inline placed(X):
x = X
{ { place = ($startpos, $endpos); value = x } }
(* -------------------------------------------------------------------------- *)
(* In a right-flexible list, the last delimiter is optional, i.e., [delim] can
be viewed as a terminator or a separator, as desired. *)
(* There are several ways of expressing this. One could say it is either a
separated list or a terminated list; this works if one uses right recursive
lists. Or, one could say that it is a separated list followed with an
optional delimiter; this works if one uses a left-recursive list. The
following formulation is direct and seems most natural. It should lead to
the smallest possible automaton. *)
right_flexible_list(delim, X):
| (* nothing *)
{ [] }
| x = X
{ [x] }
| x = X delim xs = right_flexible_list(delim, X)
{ x :: xs }
(* In a left-flexible list, the first delimiter is optional, i.e., [delim] can
be viewed as an opening or as a separator, as desired. *)
(* Again, there are several ways of expressing this, and again, I suppose the
following formulation is simplest. It is the mirror image of the above
definition, so it is naturally left-recursive, this time. *)
reverse_left_flexible_list(delim, X):
| (* nothing *)
{ [] }
| x = X
{ [x] }
| xs = reverse_left_flexible_list(delim, X) delim x = X
{ x :: xs }
%inline left_flexible_list(delim, X):
xs = reverse_left_flexible_list(delim, X)
{ List.rev xs }