Annotation of /trunk/src/compiler/typechecker/typechecker.sml

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1 :	jhr	69	(* typechecker.sml
2 :			*
3 :			* COPYRIGHT (c) 2010 The Diderot Project (http://diderot.cs.uchicago.edu)
4 :			* All rights reserved.
5 :	jhr	228	*
6 :	jhr	69	*)
7 :
8 :			structure Typechecker : sig
9 :
10 :	jhr	88	exception Error
11 :
12 :	jhr	86	val check : Error.err_stream -> ParseTree.program -> AST.program
13 :	jhr	69
14 :			end = struct
15 :
16 :	jhr	70	structure PT = ParseTree
17 :	jhr	69	structure Ty = Types
18 :	jhr	96	structure TU = TypeUtil
19 :	jhr	81	structure U = Util
20 :	jhr	69
21 :	jhr	228	datatype scope = GlobalScope | ActorScope | MethodScope | InitScope
22 :	jhr	169
23 :	jhr	228	type env = {scope : scope, env : Env.env}
24 :
25 :			fun actorScope {scope, env} = {scope=ActorScope, env=env}
26 :			fun methodScope {scope, env} = {scope=MethodScope, env=env}
27 :			fun initScope {scope, env} = {scope=InitScope, env=env}
28 :
29 :			fun inActor {scope=ActorScope, env} = true
30 :			| inActor {scope=MethodScope, ...} = true
31 :			| inActor _ = false
32 :
33 :			fun insertLocal ({scope, env}, x, x') = {scope=scope, env=Env.insertLocal(env, x, x')}
34 :			fun insertGlobal ({scope, env}, x, x') = {scope=scope, env=Env.insertGlobal(env, x, x')}
35 :
36 :	jhr	88	exception Error
37 :
38 :	jhr	86	type context = Error.err_stream * Error.span
39 :
40 :			fun withContext ((errStrm, _), {span, tree}) =
41 :			((errStrm, span), tree)
42 :			fun withEnvAndContext (env, (errStrm, _), {span, tree}) =
43 :			(env, (errStrm, span), tree)
44 :
45 :	jhr	88	fun error ((errStrm, span), msg) = (
46 :			Error.errorAt(errStrm, span, msg);
47 :			raise Error)
48 :	jhr	86
49 :	jhr	88	datatype token
50 :			= S of string | A of Atom.atom
51 :			| V of AST.var | TY of Types.ty | TYS of Types.ty list
52 :
53 :			fun err (cxt, toks) = let
54 :			fun tok2str (S s) = s
55 :			| tok2str (A a) = Atom.toString a
56 :			| tok2str (V x) = Var.nameOf x
57 :	jhr	96	| tok2str (TY ty) = TU.toString ty
58 :	jhr	88	| tok2str (TYS []) = "()"
59 :	jhr	96	| tok2str (TYS[ty]) = TU.toString ty
60 :	jhr	88	| tok2str (TYS tys) = String.concat[
61 :	jhr	96	"(", String.concatWith " * " (List.map TU.toString tys), ")"
62 :	jhr	88	]
63 :			in
64 :			error(cxt, List.map tok2str toks)
65 :			end
66 :
67 :	jhr	83	val realZero = AST.E_Lit(Literal.Float(FloatLit.zero true))
68 :
69 :	jhr	70	(* check a differentiation level, which muse be >= 0 *)
70 :			fun checkDiff (cxt, k) =
71 :			if (k < 0)
72 :			then raise Fail "differentiation must be >= 0"
73 :	jhr	75	else Ty.DiffConst(IntInf.toInt k)
74 :	jhr	70
75 :			(* check a dimension, which must be 2 or 3 *)
76 :			fun checkDim (cxt, d) =
77 :	jhr	82	if (d <= 0)
78 :			then raise Fail "invalid dimension; must be > 0"
79 :	jhr	75	else Ty.DimConst(IntInf.toInt d)
80 :	jhr	70
81 :			(* check a shape *)
82 :			fun checkShape (cxt, shape) = let
83 :			fun chkDim d = if (d < 1)
84 :			then raise Fail "invalid shape dimension; must be >= 1"
85 :	jhr	75	else Ty.DimConst(IntInf.toInt d)
86 :	jhr	70	in
87 :			Ty.Shape(List.map chkDim shape)
88 :			end
89 :
90 :	jhr	69	(* check the well-formedness of a type and translate it to an AST type *)
91 :	jhr	70	fun checkTy (cxt, ty) = (case ty
92 :	jhr	86	of PT.T_Mark m => checkTy(withContext(cxt, m))
93 :	jhr	70	| PT.T_Bool => Ty.T_Bool
94 :			| PT.T_Int => Ty.T_Int
95 :			| PT.T_Real => Ty.realTy
96 :			| PT.T_String => Ty.T_String
97 :			| PT.T_Vec n => (* NOTE: the parser guarantees that 2 <= n <= 4 *)
98 :			Ty.vecTy(IntInf.toInt n)
99 :			| PT.T_Kernel k => Ty.T_Kernel(checkDiff(cxt, k))
100 :			| PT.T_Field{diff, dim, shape} => Ty.T_Field{
101 :			diff = checkDiff (cxt, diff),
102 :			dim = checkDim (cxt, dim),
103 :			shape = checkShape (cxt, shape)
104 :			}
105 :			| PT.T_Tensor shape => Ty.T_Tensor(checkShape(cxt, shape))
106 :			| PT.T_Image{dim, shape} => Ty.T_Image{
107 :			dim = checkDim (cxt, dim),
108 :			shape = checkShape (cxt, shape)
109 :			}
110 :	jhr	99	| PT.T_Array(ty, dims) => raise Fail "Array type not supported"
111 :	jhr	69	(* end case *))
112 :
113 :	jhr	71	fun checkLit lit = (case lit
114 :			of (Literal.Int _) => (AST.E_Lit lit, Ty.T_Int)
115 :			| (Literal.Float _) => (AST.E_Lit lit, Ty.realTy)
116 :			| (Literal.String s) => (AST.E_Lit lit, Ty.T_String)
117 :			| (Literal.Bool _) => (AST.E_Lit lit, Ty.T_Bool)
118 :			(* end case *))
119 :
120 :	jhr	85	(* resolve overloading: we use a simple scheme that selects the first operator in the
121 :			* list that matches the argument types.
122 :			*)
123 :	jhr	91	fun resolveOverload (cxt, rator, argTys, args, candidates) = let
124 :			fun tryCandidates [] = err(cxt, [
125 :			S "unable to resolve overloaded operator \"", A rator, S "\"\n",
126 :			S " argument type is: ", TYS argTys, S "\n"
127 :	jhr	85	])
128 :			| tryCandidates (x::xs) = let
129 :			val (tyArgs, Ty.T_Fun(domTy, rngTy)) = Util.instantiate(Var.typeOf x)
130 :			in
131 :			if U.tryMatchTypes(domTy, argTys)
132 :			then (AST.E_Apply(x, tyArgs, args, rngTy), rngTy)
133 :			else tryCandidates xs
134 :			end
135 :			in
136 :			tryCandidates candidates
137 :			end
138 :
139 :	jhr	70	(* typecheck an expression and translate it to AST *)
140 :	jhr	169	fun checkExpr (env : env, cxt, e) = (case e
141 :	jhr	86	of PT.E_Mark m => checkExpr (withEnvAndContext (env, cxt, m))
142 :	jhr	169	| PT.E_Var x => (case Env.findVar (#env env, x)
143 :	jhr	171	of SOME x' => (AST.E_Var x', Var.monoTypeOf x')
144 :	jhr	88	| NONE => err(cxt, [S "undeclared variable ", A x])
145 :	jhr	71	(* end case *))
146 :			| PT.E_Lit lit => checkLit lit
147 :	jhr	81	| PT.E_OrElse(e1, e2) => let
148 :			val (e1', ty1) = checkExpr(env, cxt, e1)
149 :			val (e2', ty2) = checkExpr(env, cxt, e2)
150 :			in
151 :			case (ty1, ty2)
152 :			of (Ty.T_Bool, Ty.T_Bool) =>
153 :			(AST.E_Cond(e1', AST.E_Lit(Literal.Bool true), e2'), Ty.T_Bool)
154 :	jhr	99	| _ => err (cxt, [S "arguments to \"||\" must have bool type"])
155 :	jhr	81	(* end case *)
156 :			end
157 :			| PT.E_AndAlso(e1, e2) => let
158 :			val (e1', ty1) = checkExpr(env, cxt, e1)
159 :			val (e2', ty2) = checkExpr(env, cxt, e2)
160 :			in
161 :			case (ty1, ty2)
162 :			of (Ty.T_Bool, Ty.T_Bool) =>
163 :			(AST.E_Cond(e1', e2', AST.E_Lit(Literal.Bool false)), Ty.T_Bool)
164 :	jhr	99	| _ => err (cxt, [S "arguments to \"&&\" must have bool type"])
165 :	jhr	81	(* end case *)
166 :			end
167 :			| PT.E_BinOp(e1, rator, e2) => let
168 :			val (e1', ty1) = checkExpr(env, cxt, e1)
169 :			val (e2', ty2) = checkExpr(env, cxt, e2)
170 :			in
171 :			case Basis.findOp rator
172 :			of [rator] => let
173 :			val (tyArgs, Ty.T_Fun(domTy, rngTy)) = Util.instantiate(Var.typeOf rator)
174 :			in
175 :			if U.matchTypes(domTy, [ty1, ty2])
176 :			then (AST.E_Apply(rator, tyArgs, [e1', e2'], rngTy), rngTy)
177 :	jhr	89	else err (cxt, [
178 :			S "type error for binary operator \"", V rator, S "\"\n",
179 :			S " expected: ", TYS domTy, S "\n",
180 :			S " but found: ", TYS[ty1, ty2], S "\n"
181 :	jhr	85	])
182 :	jhr	81	end
183 :	jhr	91	| ovldList => resolveOverload (cxt, rator, [ty1, ty2], [e1', e2'], ovldList)
184 :	jhr	81	(* end case *)
185 :			end
186 :			| PT.E_UnaryOp(rator, e) => let
187 :			val (e', ty) = checkExpr(env, cxt, e)
188 :			in
189 :			case Basis.findOp rator
190 :			of [rator] => let
191 :			val (tyArgs, Ty.T_Fun([domTy], rngTy)) = Util.instantiate(Var.typeOf rator)
192 :			in
193 :			if U.matchType(domTy, ty)
194 :			then (AST.E_Apply(rator, tyArgs, [e'], rngTy), rngTy)
195 :	jhr	89	else err (cxt, [
196 :			S "type error for unary operator \"", V rator, S "\"\n",
197 :			S " expected: ", TY domTy, S "\n",
198 :			S " but found: ", TY ty, S "\n"
199 :	jhr	85	])
200 :	jhr	81	end
201 :	jhr	91	| ovldList => resolveOverload (cxt, rator, [ty], [e'], ovldList)
202 :	jhr	81	(* end case *)
203 :			end
204 :			| PT.E_Tuple args => let
205 :			val (args, tys) = checkExprList (env, cxt, args)
206 :			in
207 :			raise Fail "E_Tuple not yet implemented"
208 :			end
209 :			| PT.E_Apply(f, args) => let
210 :			val (args, tys) = checkExprList (env, cxt, args)
211 :			in
212 :	jhr	169	case Env.findFunc (#env env, f)
213 :			of SOME f =>
214 :	jhr	228	if (inActor env) andalso (Basis.isRestricted f)
215 :			then err(cxt, [S "use of restricted operation ", V f, S " in actor body"])
216 :			else (case Util.instantiate(Var.typeOf f)
217 :	jhr	169	of (tyArgs, Ty.T_Fun(domTy, rngTy)) =>
218 :			if U.matchTypes(domTy, tys)
219 :			then (AST.E_Apply(f, tyArgs, args, rngTy), rngTy)
220 :			else err(cxt, [
221 :			S "type error in application of ", V f, S "\n",
222 :			S " expected: ", TYS domTy, S "\n",
223 :			S " but found: ", TYS tys, S "\n"
224 :			])
225 :			| _ => err(cxt, [S "application of non-function ", V f])
226 :			(* end case *))
227 :	jhr	99	| NONE => err(cxt, [S "unknown function ", A f])
228 :	jhr	81	(* end case *)
229 :			end
230 :	jhr	86	| PT.E_Cons args => let
231 :			val (args, ty::tys) = checkExprList (env, cxt, args)
232 :	jhr	81	in
233 :	jhr	96	case TU.pruneHead ty
234 :	jhr	86	of Ty.T_Tensor shape => let
235 :			fun chkTy ty' = U.matchType(ty, ty')
236 :			val resTy = Ty.T_Tensor(Ty.shapeExt(shape, Ty.DimConst(List.length args)))
237 :	jhr	83	in
238 :	jhr	86	if List.all chkTy tys
239 :			then (AST.E_Cons args, resTy)
240 :	jhr	99	else err(cxt, [S "arguments of tensor construction must have same type"])
241 :	jhr	83	end
242 :	jhr	99	| _ => err(cxt, [S "Invalid argument type for tensor construction"])
243 :	jhr	83	(* end case *)
244 :	jhr	81	end
245 :	jhr	86	| PT.E_Real e => (case checkExpr (env, cxt, e)
246 :			of (e', Ty.T_Int) =>
247 :			(AST.E_Apply(BasisVars.i2r, [], [e'], Ty.realTy), Ty.realTy)
248 :	jhr	99	| _ => err(cxt, [S "argument of real conversion must be int"])
249 :	jhr	86	(* end case *))
250 :	jhr	70	(* end case *))
251 :
252 :	jhr	81	(* typecheck a list of expressions returning a list of AST expressions and a list
253 :			* of types of the expressions.
254 :			*)
255 :			and checkExprList (env, cxt, exprs) = let
256 :			fun chk (e, (es, tys)) = let
257 :			val (e, ty) = checkExpr (env, cxt, e)
258 :			in
259 :			(e::es, ty::tys)
260 :			end
261 :			in
262 :			List.foldr chk ([], []) exprs
263 :			end
264 :
265 :	jhr	72	fun checkVarDecl (env, cxt, kind, d) = (case d
266 :	jhr	86	of PT.VD_Mark m => checkVarDecl (env, (#1 cxt, #span m), kind, #tree m)
267 :	jhr	72	| PT.VD_Decl(ty, x, e) => let
268 :	jhr	81	val ty = checkTy (cxt, ty)
269 :	jhr	72	val x' = Var.new (x, kind, ty)
270 :			val (e', ty') = checkExpr (env, cxt, e)
271 :			in
272 :	jhr	99	(* FIXME: this check is not flexible enough; should allow lhs type to support
273 :			* fewer levels of differentiation than rhs provides.
274 :			*)
275 :			if U.matchType(ty, ty')
276 :			then (x, x', e')
277 :			else err(cxt, [
278 :			S "type of variable ", A x,
279 :			S " does not match type of initializer\n",
280 :			S " expected: ", TY ty, S "\n",
281 :			S " but found: ", TY ty', S "\n"
282 :			])
283 :	jhr	72	end
284 :			(* end case *))
285 :
286 :	jhr	70	(* typecheck a statement and translate it to AST *)
287 :	jhr	71	fun checkStmt (env, cxt, s) = (case s
288 :	jhr	86	of PT.S_Mark m => checkStmt (withEnvAndContext (env, cxt, m))
289 :	jhr	72	| PT.S_Block stms => let
290 :			fun chk (_, [], stms) = AST.S_Block(List.rev stms)
291 :			| chk (env, s::ss, stms) = let
292 :			val (s', env') = checkStmt (env, cxt, s)
293 :			in
294 :	jhr	81	chk (env', ss, s'::stms)
295 :	jhr	72	end
296 :			in
297 :			(chk (env, stms, []), env)
298 :			end
299 :			| PT.S_Decl vd => let
300 :	jhr	228	val (x, x', e) = checkVarDecl (methodScope env, cxt, Var.LocalVar, vd)
301 :	jhr	72	in
302 :	jhr	228	(AST.S_Decl(AST.VD_Decl(x', e)), insertLocal(env, x, x'))
303 :	jhr	72	end
304 :			| PT.S_IfThen(e, s) => let
305 :	jhr	228	val (e', ty) = checkExpr (env, cxt, e)
306 :	jhr	81	val (s', _) = checkStmt (env, cxt, s)
307 :	jhr	72	in
308 :			(* check that condition has bool type *)
309 :			case ty
310 :			of Ty.T_Bool => ()
311 :	jhr	99	| _ => err(cxt, [S "condition not boolean type"])
312 :	jhr	72	(* end case *);
313 :			(AST.S_IfThenElse(e', s', AST.S_Block[]), env)
314 :			end
315 :			| PT.S_IfThenElse(e, s1, s2) => let
316 :	jhr	228	val (e', ty) = checkExpr (env, cxt, e)
317 :	jhr	81	val (s1', _) = checkStmt (env, cxt, s1)
318 :			val (s2', _) = checkStmt (env, cxt, s2)
319 :	jhr	72	in
320 :			(* check that condition has bool type *)
321 :			case ty
322 :			of Ty.T_Bool => ()
323 :	jhr	99	| _ => err(cxt, [S "condition not boolean type"])
324 :	jhr	72	(* end case *);
325 :			(AST.S_IfThenElse(e', s1', s2'), env)
326 :			end
327 :	jhr	228	| PT.S_Assign(x, e) => (case Env.findVar (#env env, x)
328 :	jhr	99	of NONE => err(cxt, [
329 :			S "undefined variable ", A x
330 :			])
331 :	jhr	72	| SOME x' => let
332 :	jhr	99	(* FIXME: check for polymorphic variables *)
333 :			val ([], ty) = Var.typeOf x'
334 :	jhr	228	val (e', ty') = checkExpr (env, cxt, e)
335 :	jhr	72	in
336 :	jhr	99	if U.matchType(ty, ty')
337 :			then (x, x', e')
338 :			else err(cxt, [
339 :			S "type of assigned variable ", A x,
340 :			S " does not match type of rhs\n",
341 :			S " expected: ", TY ty, S "\n",
342 :			S " but found: ", TY ty', S "\n"
343 :			]);
344 :	jhr	72	(* check that x' is mutable *)
345 :			case Var.kindOf x'
346 :			of Var.ActorStateVar => ()
347 :	jhr	173	| Var.ActorOutputVar => ()
348 :	jhr	72	| Var.LocalVar => ()
349 :	jhr	99	| _ => err(cxt, [
350 :			S "assignment to immutable variable ", A x
351 :			])
352 :	jhr	72	(* end case *);
353 :			(AST.S_Assign(x', e'), env)
354 :			end
355 :			(* end case *))
356 :			| PT.S_New(actor, args) => let
357 :	jhr	228	val argsAndTys' = List.map (fn e => checkExpr(env, cxt, e)) args
358 :	jhr	81	val (args', tys') = ListPair.unzip argsAndTys'
359 :	jhr	72	in
360 :	jhr	228	case #scope env
361 :			of MethodScope => ()
362 :			| InitScope => ()
363 :			| _ => err(cxt, [S "invalid scope for new actor"])
364 :			(* end case *);
365 :	jhr	72	(* FIXME: check that actor is defined and has the argument types match *)
366 :	jhr	81	(AST.S_New(actor, args'), env)
367 :	jhr	72	end
368 :	jhr	228	| PT.S_Die => (
369 :			case #scope env
370 :			of ActorScope => ()
371 :			| _ => err(cxt, [S "\"die\" statment outside of actor body"])
372 :			(* end case *);
373 :			(AST.S_Die, env))
374 :			| PT.S_Stabilize => (
375 :			case #scope env
376 :			of ActorScope => ()
377 :			| _ => err(cxt, [S "\"stabilize\" statment outside of actor body"])
378 :			(* end case *);
379 :			(AST.S_Stabilize, env))
380 :	jhr	70	(* end case *))
381 :
382 :	jhr	82	fun checkParams (env, cxt, params) = let
383 :			fun chkParam (env, cxt, param) = (case param
384 :	jhr	86	of PT.P_Mark m => chkParam (withEnvAndContext (env, cxt, m))
385 :	jhr	82	| PT.P_Param(ty, x) => let
386 :			val x' = Var.new(x, AST.ActorParam, checkTy (cxt, ty))
387 :			in
388 :	jhr	228	(x', insertLocal(env, x, x'))
389 :	jhr	82	end
390 :			(* end case *))
391 :			fun chk (param, (xs, env)) = let
392 :			val (x, env) = chkParam (env, cxt, param)
393 :			in
394 :			(x::xs, env)
395 :			end
396 :			in
397 :			(* FIXME: need to check for multiple occurences of the same parameter name! *)
398 :			List.foldr chk ([], env) params
399 :			end
400 :
401 :			fun checkMethod (env, cxt, meth) = (case meth
402 :	jhr	86	of PT.M_Mark m => checkMethod (withEnvAndContext (env, cxt, m))
403 :	jhr	82	| PT.M_Method(name, body) => let
404 :	jhr	228	val (body, _) = checkStmt(methodScope env, cxt, body)
405 :	jhr	82	in
406 :			AST.M_Method(name, body)
407 :			end
408 :			(* end case *))
409 :
410 :			fun checkActor (env, cxt, {name, params, state, methods}) = let
411 :			(* check the actor parameters *)
412 :			val (params, env) = checkParams (env, cxt, params)
413 :			(* check the actor state variable definitions *)
414 :			val (vds, env) = let
415 :	jhr	164	fun checkStateVar ((isOut, vd), (vds, env)) = let
416 :	jhr	173	val kind = if isOut then AST.ActorOutputVar else AST.ActorStateVar
417 :	jhr	228	val (x, x', e') = checkVarDecl (env, cxt, kind, vd)
418 :	jhr	82	in
419 :	jhr	228	(* check that output variables have value types *)
420 :			if isOut andalso not(TU.isValueType(Var.monoTypeOf x'))
421 :			then err(cxt, [
422 :			S "output variable ", V x', S " has non-value type ",
423 :			TY(Var.monoTypeOf x')
424 :			])
425 :			else ();
426 :			(AST.VD_Decl(x', e')::vds, insertLocal(env, x, x'))
427 :	jhr	82	end
428 :			val (vds, env) = List.foldl checkStateVar ([], env) state
429 :			in
430 :			(List.rev vds, env)
431 :			end
432 :			(* check the actor methods *)
433 :			val methods = List.map (fn m => checkMethod (env, cxt, m)) methods
434 :			in
435 :			AST.D_Actor{name = name, params = params, state = vds, methods = methods}
436 :			end
437 :
438 :	jhr	89	fun checkCreate (env, cxt, PT.C_Mark m) = checkCreate (withEnvAndContext (env, cxt, m))
439 :			| checkCreate (env, cxt, PT.C_Create(actor, args)) = let
440 :	jhr	228	val (args, tys) = checkExprList (env, cxt, args)
441 :	jhr	89	in
442 :			(* FIXME: check against actor definition *)
443 :			AST.C_Create(actor, args)
444 :			end
445 :
446 :			fun checkIter (env, cxt, PT.I_Mark m) = checkIter (withEnvAndContext (env, cxt, m))
447 :			| checkIter (env, cxt, PT.I_Range(x, e1, e2)) = let
448 :	jhr	228	val (e1', ty1) = checkExpr (env, cxt, e1)
449 :			val (e2', ty2) = checkExpr (env, cxt, e2)
450 :	jhr	89	val x' = Var.new(x, Var.LocalVar, Ty.T_Int)
451 :	jhr	228	val env' = insertLocal(env, x, x')
452 :	jhr	89	in
453 :			case (ty1, ty2)
454 :			of (Ty.T_Int, Ty.T_Int) => (AST.I_Range(x', e1', e2'), env')
455 :			| _ => err(cxt, [
456 :			S "range expressions must have integer type\n",
457 :			S " but found: ", TY ty1, S " .. ", TY ty2, S "\n"
458 :			])
459 :			(* end case *)
460 :			end
461 :
462 :			fun checkIters (env, cxt, iters) = let
463 :			fun chk (env, [], iters) = (List.rev iters, env)
464 :			| chk (env, iter::rest, iters) = let
465 :			val (iter, env) = checkIter (env, cxt, iter)
466 :			in
467 :			chk (env, rest, iter::iters)
468 :			end
469 :			in
470 :			chk (env, iters, [])
471 :			end
472 :
473 :	jhr	71	fun checkDecl (env, cxt, d) = (case d
474 :	jhr	86	of PT.D_Mark m => checkDecl (withEnvAndContext (env, cxt, m))
475 :	jhr	72	| PT.D_Input(ty, x, optExp) => let
476 :	jhr	71	val ty = checkTy(cxt, ty)
477 :			val x' = Var.new(x, Var.InputVar, ty)
478 :			val dcl = (case optExp
479 :			of NONE => AST.D_Input(x', NONE)
480 :			| SOME e => let
481 :	jhr	228	val (e', ty') = checkExpr (env, cxt, e)
482 :	jhr	71	in
483 :	jhr	89	if U.matchType (ty, ty')
484 :			then AST.D_Input(x', SOME e')
485 :			else err(cxt, [
486 :			S "definition of ", V x', S " has wrong type\n",
487 :			S " expected: ", TY ty, S "\n",
488 :			S " but found: ", TY ty', S "\n"
489 :			])
490 :	jhr	71	end
491 :			(* end case *))
492 :			in
493 :	jhr	228	(* check that input variables have value types *)
494 :			if not(TU.isValueType ty)
495 :			then err(cxt, [S "input variable ", V x', S " has non-value type ", TY ty])
496 :			else ();
497 :			(dcl, insertGlobal(env, x, x'))
498 :	jhr	71	end
499 :	jhr	72	| PT.D_Var vd => let
500 :	jhr	228	val (x, x', e') = checkVarDecl (env, cxt, Var.GlobalVar, vd)
501 :	jhr	72	in
502 :	jhr	228	(AST.D_Var(AST.VD_Decl(x', e')), insertGlobal(env, x, x'))
503 :	jhr	72	end
504 :	jhr	228	| PT.D_Actor arg => (checkActor(actorScope env, cxt, arg), env)
505 :	jhr	89	| PT.D_InitialArray(create, iterators) => let
506 :	jhr	228	val env = initScope env
507 :	jhr	89	val (iterators, env') = checkIters (env, cxt, iterators)
508 :			val create = checkCreate (env', cxt, create)
509 :			in
510 :			(AST.D_InitialArray(create, iterators), env)
511 :			end
512 :			| PT.D_InitialCollection(create, iterators) => let
513 :	jhr	228	val env = initScope env
514 :	jhr	89	val (iterators, env') = checkIters (env, cxt, iterators)
515 :			val create = checkCreate (env', cxt, create)
516 :			in
517 :			(AST.D_InitialCollection(create, iterators), env)
518 :			end
519 :	jhr	70	(* end case *))
520 :
521 :	jhr	86	fun check errStrm (PT.Program{span, tree}) = let
522 :			val cxt = (errStrm, span)
523 :	jhr	81	fun chk (env, [], dcls') = AST.Program(List.rev dcls')
524 :			| chk (env, dcl::dcls, dcls') = let
525 :	jhr	86	val (dcl', env) = checkDecl (env, cxt, dcl)
526 :	jhr	81	in
527 :			chk (env, dcls, dcl'::dcls')
528 :			end
529 :			in
530 :	jhr	228	chk ({scope=GlobalScope, env=Basis.env}, tree, [])
531 :	jhr	81	end
532 :	jhr	70
533 :	jhr	69	end

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