Annotation of /branches/vis12/src/compiler/typechecker/typechecker.sml

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1 :	jhr	69	(* typechecker.sml
2 :			*
3 :	jhr	2149	* COPYRIGHT (c) 2013 The Diderot Project (http://diderot-language.cs.uchicago.edu)
4 :	jhr	69	* All rights reserved.
5 :	jhr	228	*
6 :	jhr	1116	* TODO:
7 :	jhr	2149	* check for unreachable code and prune it (see simplify/simplify.sml)
8 :			* error recovery so that we can detect multiple errors in a single compile
9 :			* check that functions have a return on all paths
10 :	jhr	2151	* check that the args of strand creation have the same type and number as the params
11 :	jhr	69	*)
12 :
13 :			structure Typechecker : sig
14 :
15 :	jhr	86	val check : Error.err_stream -> ParseTree.program -> AST.program
16 :	jhr	69
17 :			end = struct
18 :
19 :	jhr	1116	structure BV = BasisVars
20 :	jhr	70	structure PT = ParseTree
21 :	jhr	69	structure Ty = Types
22 :	jhr	96	structure TU = TypeUtil
23 :	jhr	81	structure U = Util
24 :	jhr	69
25 :	jhr	2149	(* exception to abort typechecking when we hit an error. Eventually, we should continue
26 :			* checking for more errors and not use this.
27 :			*)
28 :			exception TypeError
29 :
30 :	jhr	2133	datatype scope
31 :			= GlobalScope
32 :			| FunctionScope of Ty.ty
33 :			| StrandScope
34 :			| MethodScope
35 :			| InitScope
36 :	jhr	169
37 :	jhr	1116	type env = {
38 :			scope : scope,
39 :			bindings : Error.location AtomMap.map,
40 :			env : Env.env
41 :			}
42 :	jhr	228
43 :	jhr	1116	type context = Error.err_stream * Error.span
44 :	jhr	228
45 :	jhr	1116	(* start a new scope *)
46 :	jhr	2133	(* QUESTION: do we want to restrict access to globals from a function? *)
47 :			fun functionScope ({scope, bindings, env}, ty) =
48 :	jhr	2149	{scope=FunctionScope ty, bindings=AtomMap.empty, env=env}
49 :	jhr	1116	fun strandScope {scope, bindings, env} =
50 :			{scope=StrandScope, bindings=AtomMap.empty, env=env}
51 :			fun methodScope {scope, bindings, env} =
52 :			{scope=MethodScope, bindings=AtomMap.empty, env=env}
53 :			fun initScope {scope, bindings, env} =
54 :			{scope=InitScope, bindings=AtomMap.empty, env=env}
55 :			fun blockScope {scope, bindings, env} =
56 :			{scope=scope, bindings=AtomMap.empty, env=env}
57 :
58 :			fun inStrand {scope=StrandScope, bindings, env} = true
59 :	jhr	511	| inStrand {scope=MethodScope, ...} = true
60 :			| inStrand _ = false
61 :	jhr	228
62 :	jhr	2133	fun insertFunc ({scope, bindings, env}, cxt, f, f') = {
63 :			scope=scope,
64 :			bindings = AtomMap.insert(bindings, f, Error.location cxt),
65 :			env=Env.insertFunc(env, f, Env.UserFun f')
66 :			}
67 :	jhr	1116	fun insertLocal ({scope, bindings, env}, cxt, x, x') = {
68 :			scope=scope,
69 :			bindings = AtomMap.insert(bindings, x, Error.location cxt),
70 :			env=Env.insertLocal(env, x, x')
71 :			}
72 :			fun insertGlobal ({scope, bindings, env}, cxt, x, x') = {
73 :			scope=scope,
74 :			bindings = AtomMap.insert(bindings, x, Error.location cxt),
75 :			env=Env.insertGlobal(env, x, x')
76 :			}
77 :	jhr	228
78 :	jhr	86	fun withContext ((errStrm, _), {span, tree}) =
79 :			((errStrm, span), tree)
80 :			fun withEnvAndContext (env, (errStrm, _), {span, tree}) =
81 :			(env, (errStrm, span), tree)
82 :
83 :	jhr	88	fun error ((errStrm, span), msg) = (
84 :			Error.errorAt(errStrm, span, msg);
85 :	jhr	2149	raise TypeError)
86 :	jhr	86
87 :	jhr	88	datatype token
88 :			= S of string | A of Atom.atom
89 :			| V of AST.var | TY of Types.ty | TYS of Types.ty list
90 :
91 :	jhr	1925	fun tysToString tys = String.concat[
92 :			"(", String.concatWith " * " (List.map TU.toString tys), ")"
93 :			]
94 :
95 :	jhr	88	fun err (cxt, toks) = let
96 :			fun tok2str (S s) = s
97 :	jhr	2050	| tok2str (A a) = concat["'", Atom.toString a, "'"]
98 :			| tok2str (V x) = concat["'", Var.nameOf x, "'"]
99 :	jhr	96	| tok2str (TY ty) = TU.toString ty
100 :	jhr	88	| tok2str (TYS []) = "()"
101 :	jhr	96	| tok2str (TYS[ty]) = TU.toString ty
102 :	jhr	1925	| tok2str (TYS tys) = tysToString tys
103 :	jhr	88	in
104 :			error(cxt, List.map tok2str toks)
105 :			end
106 :
107 :	jhr	1116	fun checkForRedef (env : env, cxt : context, x) = (case AtomMap.find(#bindings env,x)
108 :			of SOME loc => err (cxt, [
109 :			S "redefinition of ", A x, S ", previous definition at ",
110 :			S(Error.locToString loc)
111 :			])
112 :			| NONE => ()
113 :			(* end case *))
114 :
115 :	jhr	83	val realZero = AST.E_Lit(Literal.Float(FloatLit.zero true))
116 :
117 :	jhr	2149	(* check a differentiation level, which must be >= 0 *)
118 :	jhr	70	fun checkDiff (cxt, k) =
119 :			if (k < 0)
120 :	jhr	1116	then err (cxt, [S "differentiation must be >= 0"])
121 :	jhr	75	else Ty.DiffConst(IntInf.toInt k)
122 :	jhr	70
123 :	jhr	2134	(* check a sequence dimension, which must be > 0 *)
124 :			fun checkSeqDim (cxt, d) =
125 :			if (d < 0)
126 :			then err (cxt, [S "invalid dimension; must be positive"])
127 :			else Ty.DimConst(IntInf.toInt d)
128 :
129 :	jhr	1116	(* check a dimension, which must be 1, 2 or 3 *)
130 :	jhr	70	fun checkDim (cxt, d) =
131 :	jhr	1116	if (d < 1) orelse (3 < d)
132 :			then err (cxt, [S "invalid dimension; must be 1, 2, or 3"])
133 :	jhr	75	else Ty.DimConst(IntInf.toInt d)
134 :	jhr	70
135 :			(* check a shape *)
136 :	jhr	1116	fun checkShape (cxt, shape) = let
137 :			fun checkDim d =
138 :			if (d <= 1)
139 :			then err (cxt, [S "invalid tensor-shape dimension; must be > 1"])
140 :			else Ty.DimConst(IntInf.toInt d)
141 :	jhr	70	in
142 :	jhr	1116	Ty.Shape(List.map checkDim shape)
143 :	jhr	70	end
144 :
145 :	jhr	69	(* check the well-formedness of a type and translate it to an AST type *)
146 :	jhr	70	fun checkTy (cxt, ty) = (case ty
147 :	jhr	86	of PT.T_Mark m => checkTy(withContext(cxt, m))
148 :	jhr	70	| PT.T_Bool => Ty.T_Bool
149 :			| PT.T_Int => Ty.T_Int
150 :			| PT.T_Real => Ty.realTy
151 :			| PT.T_String => Ty.T_String
152 :			| PT.T_Vec n => (* NOTE: the parser guarantees that 2 <= n <= 4 *)
153 :			Ty.vecTy(IntInf.toInt n)
154 :			| PT.T_Kernel k => Ty.T_Kernel(checkDiff(cxt, k))
155 :			| PT.T_Field{diff, dim, shape} => Ty.T_Field{
156 :			diff = checkDiff (cxt, diff),
157 :			dim = checkDim (cxt, dim),
158 :			shape = checkShape (cxt, shape)
159 :			}
160 :			| PT.T_Tensor shape => Ty.T_Tensor(checkShape(cxt, shape))
161 :			| PT.T_Image{dim, shape} => Ty.T_Image{
162 :			dim = checkDim (cxt, dim),
163 :			shape = checkShape (cxt, shape)
164 :			}
165 :	jhr	1640	| PT.T_Seq(ty, dim) => let
166 :			val ty = checkTy(cxt, ty)
167 :			in
168 :	jhr	1687	if TU.isFixedSizeType ty
169 :	jhr	2134	then Ty.T_Sequence(ty, checkSeqDim (cxt, dim))
170 :	jhr	1687	else err(cxt, [S "elements of sequence types must be fixed-size types"])
171 :	jhr	1640	end
172 :	jhr	1687	| PT.T_DynSeq ty => let
173 :			val ty = checkTy(cxt, ty)
174 :			in
175 :			if TU.isFixedSizeType ty
176 :			then Ty.T_DynSequence(ty)
177 :			else err(cxt, [S "elements of sequence types must be fixed-size types"])
178 :			end
179 :	jhr	69	(* end case *))
180 :
181 :	jhr	71	fun checkLit lit = (case lit
182 :			of (Literal.Int _) => (AST.E_Lit lit, Ty.T_Int)
183 :			| (Literal.Float _) => (AST.E_Lit lit, Ty.realTy)
184 :			| (Literal.String s) => (AST.E_Lit lit, Ty.T_String)
185 :			| (Literal.Bool _) => (AST.E_Lit lit, Ty.T_Bool)
186 :			(* end case *))
187 :
188 :	jhr	2117	fun coerceExp (Ty.T_Tensor(Ty.Shape[]), Ty.T_Int, AST.E_Lit(Literal.Int n)) =
189 :			AST.E_Lit(Literal.Float(FloatLit.fromInt n))
190 :			| coerceExp (ty1, ty2, e) = AST.E_Coerce{srcTy=ty2, dstTy=ty1, e=e}
191 :
192 :	jhr	2133	fun coerceType (dstTy, srcTy, e) = (case U.matchType(dstTy, srcTy)
193 :	jhr	1971	of U.EQ => SOME e
194 :	jhr	2133	| U.COERCE => SOME(coerceExp (dstTy, srcTy, e))
195 :	jhr	1971	| U.FAIL => NONE
196 :			(* end case *))
197 :
198 :			fun realType (ty as Ty.T_Tensor(Ty.Shape[])) = ty
199 :			| realType (ty as Ty.T_Int) = Ty.realTy
200 :			| realType ty = ty
201 :
202 :	jhr	85	(* resolve overloading: we use a simple scheme that selects the first operator in the
203 :			* list that matches the argument types.
204 :			*)
205 :	jhr	1116	fun resolveOverload (_, rator, _, _, []) = raise Fail(concat[
206 :			"resolveOverload: \"", Atom.toString rator, "\" has no candidates"
207 :			])
208 :			| resolveOverload (cxt, rator, argTys, args, candidates) = let
209 :	jhr	1971	(* FIXME: we could be more efficient by just checking for coercion matchs the first pass
210 :			* and remembering those that are not pure EQ matches.
211 :			*)
212 :			(* try to match candidates while allowing type coercions *)
213 :			fun tryMatchCandidates [] = err(cxt, [
214 :	jhr	91	S "unable to resolve overloaded operator \"", A rator, S "\"\n",
215 :			S " argument type is: ", TYS argTys, S "\n"
216 :	jhr	85	])
217 :	jhr	1971	| tryMatchCandidates (x::xs) = let
218 :			val (tyArgs, Ty.T_Fun(domTy, rngTy)) = Util.instantiate(Var.typeOf x)
219 :			in
220 :	jhr	1973	case U.tryMatchArgs (domTy, args, argTys)
221 :			of SOME args' => (AST.E_Apply(x, tyArgs, args', rngTy), rngTy)
222 :			| NONE => tryMatchCandidates xs
223 :			(* end case *)
224 :	jhr	1971	end
225 :			fun tryCandidates [] = tryMatchCandidates candidates
226 :	jhr	85	| tryCandidates (x::xs) = let
227 :			val (tyArgs, Ty.T_Fun(domTy, rngTy)) = Util.instantiate(Var.typeOf x)
228 :			in
229 :	jhr	1971	if U.tryEqualTypes(domTy, argTys)
230 :	jhr	85	then (AST.E_Apply(x, tyArgs, args, rngTy), rngTy)
231 :			else tryCandidates xs
232 :			end
233 :			in
234 :			tryCandidates candidates
235 :			end
236 :
237 :	jhr	70	(* typecheck an expression and translate it to AST *)
238 :	jhr	169	fun checkExpr (env : env, cxt, e) = (case e
239 :	jhr	86	of PT.E_Mark m => checkExpr (withEnvAndContext (env, cxt, m))
240 :	jhr	169	| PT.E_Var x => (case Env.findVar (#env env, x)
241 :	jhr	171	of SOME x' => (AST.E_Var x', Var.monoTypeOf x')
242 :	jhr	88	| NONE => err(cxt, [S "undeclared variable ", A x])
243 :	jhr	71	(* end case *))
244 :			| PT.E_Lit lit => checkLit lit
245 :	jhr	81	| PT.E_OrElse(e1, e2) => let
246 :			val (e1', ty1) = checkExpr(env, cxt, e1)
247 :			val (e2', ty2) = checkExpr(env, cxt, e2)
248 :			in
249 :			case (ty1, ty2)
250 :			of (Ty.T_Bool, Ty.T_Bool) =>
251 :	jhr	416	(AST.E_Cond(e1', AST.E_Lit(Literal.Bool true), e2', Ty.T_Bool), Ty.T_Bool)
252 :	jhr	99	| _ => err (cxt, [S "arguments to \"||\" must have bool type"])
253 :	jhr	81	(* end case *)
254 :			end
255 :			| PT.E_AndAlso(e1, e2) => let
256 :			val (e1', ty1) = checkExpr(env, cxt, e1)
257 :			val (e2', ty2) = checkExpr(env, cxt, e2)
258 :			in
259 :			case (ty1, ty2)
260 :			of (Ty.T_Bool, Ty.T_Bool) =>
261 :	jhr	416	(AST.E_Cond(e1', e2', AST.E_Lit(Literal.Bool false), Ty.T_Bool), Ty.T_Bool)
262 :	jhr	99	| _ => err (cxt, [S "arguments to \"&&\" must have bool type"])
263 :	jhr	81	(* end case *)
264 :			end
265 :	jhr	370	| PT.E_Cond(e1, cond, e2) => let
266 :			val (e1', ty1) = checkExpr(env, cxt, e1)
267 :			val (e2', ty2) = checkExpr(env, cxt, e2)
268 :			in
269 :			case checkExpr(env, cxt, cond)
270 :			of (cond', Ty.T_Bool) =>
271 :	jhr	1687	if U.equalType(ty1, ty2)
272 :	jhr	416	then (AST.E_Cond(cond', e1', e2', ty1), ty1)
273 :	jhr	370	else err (cxt, [
274 :	jhr	2133	S "types do not match in conditional expression\n",
275 :	jhr	1116	S " true branch: ", TY ty1, S "\n",
276 :	jhr	370	S " false branch: ", TY ty2
277 :			])
278 :			| (_, ty') => err (cxt, [S "expected bool type, but found ", TY ty'])
279 :			(* end case *)
280 :			end
281 :	jhr	81	| PT.E_BinOp(e1, rator, e2) => let
282 :			val (e1', ty1) = checkExpr(env, cxt, e1)
283 :			val (e2', ty2) = checkExpr(env, cxt, e2)
284 :			in
285 :	jhr	1116	if Atom.same(rator, BasisNames.op_dot)
286 :			(* we have to handle inner product as a special case, because out type
287 :			* system cannot express the constraint that the type is
288 :			* ALL[sigma1, d1, sigma2] . tensor[sigma1, d1] * tensor[d1, sigma2] -> tensor[sigma1, sigma2]
289 :			*)
290 :			then (case (TU.prune ty1, TU.prune ty2)
291 :			of (Ty.T_Tensor(s1 as Ty.Shape(dd1 as _::_)), Ty.T_Tensor(s2 as Ty.Shape(d2::dd2))) => let
292 :			val (dd1, d1) = let
293 :			fun splitLast (prefix, [d]) = (List.rev prefix, d)
294 :			| splitLast (prefix, d::dd) = splitLast (d::prefix, dd)
295 :			| splitLast (_, []) = raise Fail "impossible"
296 :			in
297 :			splitLast ([], dd1)
298 :			end
299 :			val (tyArgs, Ty.T_Fun(domTy, rngTy)) = Util.instantiate(Var.typeOf BV.op_inner)
300 :			val resTy = Ty.T_Tensor(Ty.Shape(dd1@dd2))
301 :			in
302 :	jhr	1687	if U.equalDim(d1, d2)
303 :			andalso U.equalTypes(domTy, [ty1, ty2])
304 :			andalso U.equalType(rngTy, resTy)
305 :	jhr	1116	then (AST.E_Apply(BV.op_inner, tyArgs, [e1', e2'], rngTy), rngTy)
306 :			else err (cxt, [
307 :			S "type error for arguments of binary operator \"•\"\n",
308 :			S " found: ", TYS[ty1, ty2], S "\n"
309 :			])
310 :			end
311 :			| (ty1, ty2) => err (cxt, [
312 :			S "type error for arguments of binary operator \"•\"\n",
313 :			S " found: ", TYS[ty1, ty2], S "\n"
314 :			])
315 :			(* end case *))
316 :	jhr	1945	else if Atom.same(rator, BasisNames.op_colon)
317 :			then (case (TU.prune ty1, TU.prune ty2)
318 :			of (Ty.T_Tensor(s1 as Ty.Shape(dd1 as _::_::_)), Ty.T_Tensor(s2 as Ty.Shape(d21::d22::dd2))) => let
319 :			val (dd1, d11, d12) = let
320 :			fun splitLast (prefix, [d1, d2]) = (List.rev prefix, d1, d2)
321 :			| splitLast (prefix, d::dd) = splitLast (d::prefix, dd)
322 :			| splitLast (_, []) = raise Fail "impossible"
323 :			in
324 :			splitLast ([], dd1)
325 :			end
326 :			val (tyArgs, Ty.T_Fun(domTy, rngTy)) = Util.instantiate(Var.typeOf BV.op_colon)
327 :			val resTy = Ty.T_Tensor(Ty.Shape(dd1@dd2))
328 :			in
329 :			if U.equalDim(d11, d21) andalso U.equalDim(d12, d22)
330 :			andalso U.equalTypes(domTy, [ty1, ty2])
331 :			andalso U.equalType(rngTy, resTy)
332 :			then (AST.E_Apply(BV.op_colon, tyArgs, [e1', e2'], rngTy), rngTy)
333 :			else err (cxt, [
334 :			S "type error for arguments of binary operator \":\"\n",
335 :			S " found: ", TYS[ty1, ty2], S "\n"
336 :			])
337 :			end
338 :			| (ty1, ty2) => err (cxt, [
339 :			S "type error for arguments of binary operator \":\"\n",
340 :			S " found: ", TYS[ty1, ty2], S "\n"
341 :			])
342 :			(* end case *))
343 :	jhr	1116	else (case Env.findFunc (#env env, rator)
344 :	jhr	2133	of Env.PrimFun[rator] => let
345 :	jhr	1116	val (tyArgs, Ty.T_Fun(domTy, rngTy)) = Util.instantiate(Var.typeOf rator)
346 :			in
347 :	jhr	1975	case U.matchArgs(domTy, [e1', e2'], [ty1, ty2])
348 :			of SOME args => (AST.E_Apply(rator, tyArgs, args, rngTy), rngTy)
349 :			| NONE => err (cxt, [
350 :			S "type error for binary operator \"", V rator, S "\"\n",
351 :			S " expected: ", TYS domTy, S "\n",
352 :			S " but found: ", TYS[ty1, ty2]
353 :			])
354 :			(* end case *)
355 :	jhr	1116	end
356 :	jhr	2133	| Env.PrimFun ovldList =>
357 :			resolveOverload (cxt, rator, [ty1, ty2], [e1', e2'], ovldList)
358 :			| _ => raise Fail "impossible"
359 :	jhr	1116	(* end case *))
360 :	jhr	81	end
361 :			| PT.E_UnaryOp(rator, e) => let
362 :			val (e', ty) = checkExpr(env, cxt, e)
363 :			in
364 :	jhr	1116	case Env.findFunc (#env env, rator)
365 :	jhr	2133	of Env.PrimFun[rator] => let
366 :	jhr	381	val (tyArgs, Ty.T_Fun([domTy], rngTy)) = U.instantiate(Var.typeOf rator)
367 :	jhr	81	in
368 :	jhr	1975	case coerceType (domTy, ty, e')
369 :			of SOME e' => (AST.E_Apply(rator, tyArgs, [e'], rngTy), rngTy)
370 :			| NONE => err (cxt, [
371 :			S "type error for unary operator \"", V rator, S "\"\n",
372 :			S " expected: ", TY domTy, S "\n",
373 :			S " but found: ", TY ty
374 :			])
375 :			(* end case *)
376 :	jhr	81	end
377 :	jhr	2133	| Env.PrimFun ovldList => resolveOverload (cxt, rator, [ty], [e'], ovldList)
378 :			| _ => raise Fail "impossible"
379 :	jhr	81	(* end case *)
380 :			end
381 :	jhr	381	| PT.E_Slice(e, indices) => let
382 :			val (e', ty) = checkExpr (env, cxt, e)
383 :			fun checkIndex NONE = NONE
384 :			| checkIndex (SOME e) = let
385 :			val (e', ty) = checkExpr (env, cxt, e)
386 :			in
387 :	jhr	1687	if U.equalType(ty, Ty.T_Int)
388 :	jhr	381	then (SOME e')
389 :			else err (cxt, [
390 :			S "type error in index expression\n",
391 :	jhr	1116	S " expected int, but found: ", TY ty
392 :	jhr	381	])
393 :			end
394 :			val indices' = List.map checkIndex indices
395 :			val order = List.length indices'
396 :	jhr	399	val expectedTy = TU.mkTensorTy order
397 :			val resultTy = TU.slice(expectedTy, List.map Option.isSome indices')
398 :	jhr	381	in
399 :	jhr	1687	if U.equalType(ty, expectedTy)
400 :	jhr	381	then ()
401 :			else err (cxt, [
402 :			S "type error in slice operation\n",
403 :			S " expected: ", S(Int.toString order), S "-order tensor\n",
404 :	jhr	1116	S " but found: ", TY ty
405 :	jhr	381	]);
406 :	jhr	399	(AST.E_Slice(e', indices', resultTy), resultTy)
407 :	jhr	381	end
408 :	jhr	1116	| PT.E_Subscript(e1, e2) => let
409 :			val (e1', ty1) = checkExpr (env, cxt, e1)
410 :			val (e2', ty2) = checkExpr (env, cxt, e2)
411 :	jhr	1991	fun chkIndex () = if U.equalType(ty2, Ty.T_Int)
412 :			then ()
413 :			else err (cxt, [
414 :			S "expected int type for subscript index\n",
415 :			S " but found: ", TY ty2
416 :			])
417 :			fun finish rator = let
418 :			val (tyArgs, Ty.T_Fun(domTy, rngTy)) = U.instantiate(Var.typeOf rator)
419 :			in
420 :			if U.equalTypes(domTy, [ty1, ty2])
421 :			then let
422 :	jhr	2019	val exp = AST.E_Apply(rator, tyArgs, [e1', e2'], rngTy)
423 :	jhr	1991	in
424 :			(exp, rngTy)
425 :			end
426 :			else raise Fail "unexpected unification failure"
427 :			end
428 :	jhr	1116	in
429 :	jhr	1991	case TU.pruneHead ty1
430 :			of Ty.T_DynSequence _ => (
431 :			chkIndex ();
432 :			finish BV.dynSubscript)
433 :			| Ty.T_Sequence _ => (
434 :			chkIndex ();
435 :			finish BV.subscript)
436 :			| _ => err (cxt, [
437 :			S "expected sequence type for subscript\n",
438 :			S " but found: ", TY ty1
439 :			])
440 :			(* end case *)
441 :	jhr	1116	end
442 :			| PT.E_Apply(e, args) => let
443 :			fun stripMark (PT.E_Mark{tree, ...}) = stripMark tree
444 :			| stripMark e = e
445 :			val (args, tys) = checkExprList (env, cxt, args)
446 :	jhr	2133	fun checkFunApp f = (case Util.instantiate(Var.typeOf f)
447 :			of (tyArgs, Ty.T_Fun(domTy, rngTy)) => (
448 :			case U.matchArgs (domTy, args, tys)
449 :			of SOME args => (AST.E_Apply(f, tyArgs, args, rngTy), rngTy)
450 :			| NONE => err(cxt, [
451 :			S "type error in application of ", V f, S "\n",
452 :			S " expected: ", TYS domTy, S "\n",
453 :			S " but found: ", TYS tys
454 :			])
455 :			(* end case *))
456 :			| _ => err(cxt, [S "application of non-function ", V f])
457 :			(* end case *))
458 :	jhr	1116	fun checkFieldApp (e1', ty1) = (case (args, tys)
459 :			of ([e2'], [ty2]) => let
460 :	jhr	1975	val (tyArgs, Ty.T_Fun([fldTy, domTy], rngTy)) =
461 :	jhr	1687	Util.instantiate(Var.typeOf BV.op_probe)
462 :	jhr	1975	fun tyError () = err (cxt, [
463 :	jhr	1116	S "type error for field application\n",
464 :	jhr	1975	S " expected: ", TYS[fldTy, domTy], S "\n",
465 :	jhr	1116	S " but found: ", TYS[ty1, ty2]
466 :			])
467 :	jhr	1975	in
468 :			if U.equalType(fldTy, ty1)
469 :			then (case coerceType(domTy, ty2, e2')
470 :			of SOME e2' => (AST.E_Apply(BV.op_probe, tyArgs, [e1', e2'], rngTy), rngTy)
471 :			| NONE => tyError()
472 :			(* end case *))
473 :			else tyError()
474 :	jhr	1116	end
475 :			| _ => err(cxt, [S "badly formed field application"])
476 :			(* end case *))
477 :			in
478 :			case stripMark e
479 :			of PT.E_Var f => (case Env.findVar (#env env, f)
480 :			of SOME f' => checkFieldApp (AST.E_Var f', Var.monoTypeOf f')
481 :			| NONE => (case Env.findFunc (#env env, f)
482 :	jhr	2133	of Env.PrimFun[] => err(cxt, [S "unknown function ", A f])
483 :			| Env.PrimFun[f'] =>
484 :			if (inStrand env) andalso (Basis.isRestricted f')
485 :	jhr	1116	then err(cxt, [
486 :	jhr	2133	S "use of restricted operation ", V f',
487 :	jhr	1116	S " in strand body"
488 :			])
489 :	jhr	2133	else checkFunApp f'
490 :			| Env.PrimFun ovldList =>
491 :			resolveOverload (cxt, f, tys, args, ovldList)
492 :			| Env.UserFun f' => checkFunApp f'
493 :	jhr	1116	(* end case *))
494 :			(* end case *))
495 :			| _ => checkFieldApp (checkExpr (env, cxt, e))
496 :			(* end case *)
497 :			end
498 :	jhr	81	| PT.E_Tuple args => let
499 :			val (args, tys) = checkExprList (env, cxt, args)
500 :			in
501 :	jhr	1116	raise Fail "E_Tuple not yet implemented" (* FIXME *)
502 :	jhr	81	end
503 :	jhr	1116	| PT.E_Sequence args => let
504 :	jhr	1640	val (args, ty::tys) = checkExprList (env, cxt, args)
505 :	jhr	81	in
506 :	jhr	1687	if TU.isFixedSizeType(TU.pruneHead ty)
507 :	jhr	1640	then let
508 :	jhr	1687	fun chkTy ty' = U.equalType(ty, ty')
509 :	jhr	1640	val resTy = Ty.T_Sequence(ty, Ty.DimConst(List.length args))
510 :			in
511 :			if List.all chkTy tys
512 :	jhr	1688	then (AST.E_Seq args, resTy)
513 :	jhr	1640	else err(cxt, [S "arguments of sequence expression must have same type"])
514 :			end
515 :			else err(cxt, [S "sequence expression of non-value argument type"])
516 :	jhr	81	end
517 :	jhr	86	| PT.E_Cons args => let
518 :	jhr	1971	val (args, tys as ty::_) = checkExprList (env, cxt, args)
519 :	jhr	81	in
520 :	jhr	1971	case realType(TU.pruneHead ty)
521 :	jhr	475	of ty as Ty.T_Tensor shape => let
522 :			val Ty.Shape dd = TU.pruneShape shape (* NOTE: this may fail if we allow user polymorphism *)
523 :			val resTy = Ty.T_Tensor(Ty.Shape(Ty.DimConst(List.length args) :: dd))
524 :	jhr	1971	fun chkArgs (arg::args, argTy::tys, args') = (case coerceType(ty, argTy, arg)
525 :			of SOME arg' => chkArgs (args, tys, arg'::args')
526 :			| NONE => err(cxt, [S "arguments of tensor construction must have same type"])
527 :			(* end case *))
528 :			| chkArgs ([], [], args') = (AST.E_Cons(List.rev args'), resTy)
529 :	jhr	83	in
530 :	jhr	1971	chkArgs (args, tys, [])
531 :	jhr	83	end
532 :	jhr	99	| _ => err(cxt, [S "Invalid argument type for tensor construction"])
533 :	jhr	83	(* end case *)
534 :	jhr	81	end
535 :	jhr	86	| PT.E_Real e => (case checkExpr (env, cxt, e)
536 :			of (e', Ty.T_Int) =>
537 :	jhr	1116	(AST.E_Apply(BV.i2r, [], [e'], Ty.realTy), Ty.realTy)
538 :	jhr	99	| _ => err(cxt, [S "argument of real conversion must be int"])
539 :	jhr	86	(* end case *))
540 :	jhr	1116	| PT.E_Id d => let
541 :			val (tyArgs, Ty.T_Fun(_, rngTy)) =
542 :			Util.instantiate(Var.typeOf(BV.identity))
543 :			in
544 :	jhr	1687	if U.equalType(Ty.T_Tensor(checkShape(cxt, [d,d])), rngTy)
545 :	jhr	1116	then (AST.E_Apply(BV.identity, tyArgs, [], rngTy), rngTy)
546 :			else raise Fail "impossible"
547 :			end
548 :			| PT.E_Zero dd => let
549 :			val (tyArgs, Ty.T_Fun(_, rngTy)) =
550 :			Util.instantiate(Var.typeOf(BV.zero))
551 :			in
552 :	jhr	1687	if U.equalType(Ty.T_Tensor(checkShape(cxt, dd)), rngTy)
553 :	jhr	1116	then (AST.E_Apply(BV.zero, tyArgs, [], rngTy), rngTy)
554 :			else raise Fail "impossible"
555 :			end
556 :	jhr	1992	| PT.E_Image nrrd => let
557 :	jhr	2011	val (tyArgs, Ty.T_Fun(_, rngTy)) = Util.instantiate(Var.typeOf(BV.fn_image))
558 :	jhr	1992	in
559 :			(AST.E_LoadNrrd(tyArgs, nrrd, rngTy), rngTy)
560 :			end
561 :			| PT.E_Load nrrd => let
562 :	jhr	2011	val (tyArgs, Ty.T_Fun(_, rngTy)) = Util.instantiate(Var.typeOf(BV.fn_load))
563 :	jhr	1992	in
564 :			(AST.E_LoadNrrd(tyArgs, nrrd, rngTy), rngTy)
565 :			end
566 :	jhr	70	(* end case *))
567 :
568 :	jhr	81	(* typecheck a list of expressions returning a list of AST expressions and a list
569 :			* of types of the expressions.
570 :			*)
571 :			and checkExprList (env, cxt, exprs) = let
572 :			fun chk (e, (es, tys)) = let
573 :			val (e, ty) = checkExpr (env, cxt, e)
574 :			in
575 :			(e::es, ty::tys)
576 :			end
577 :			in
578 :			List.foldr chk ([], []) exprs
579 :			end
580 :
581 :	jhr	72	fun checkVarDecl (env, cxt, kind, d) = (case d
582 :	jhr	86	of PT.VD_Mark m => checkVarDecl (env, (#1 cxt, #span m), kind, #tree m)
583 :	jhr	72	| PT.VD_Decl(ty, x, e) => let
584 :	jhr	81	val ty = checkTy (cxt, ty)
585 :	jhr	72	val x' = Var.new (x, kind, ty)
586 :			val (e', ty') = checkExpr (env, cxt, e)
587 :			in
588 :	jhr	1687	case coerceType (ty, ty', e')
589 :	jhr	1971	of SOME e' => (x, x', e')
590 :	jhr	1687	| NONE => err(cxt, [
591 :	jhr	99	S "type of variable ", A x,
592 :			S " does not match type of initializer\n",
593 :			S " expected: ", TY ty, S "\n",
594 :	jhr	1116	S " but found: ", TY ty'
595 :	jhr	99	])
596 :	jhr	1687	(* end case *)
597 :	jhr	72	end
598 :			(* end case *))
599 :
600 :	jhr	70	(* typecheck a statement and translate it to AST *)
601 :	jhr	71	fun checkStmt (env, cxt, s) = (case s
602 :	jhr	86	of PT.S_Mark m => checkStmt (withEnvAndContext (env, cxt, m))
603 :	jhr	72	| PT.S_Block stms => let
604 :			fun chk (_, [], stms) = AST.S_Block(List.rev stms)
605 :			| chk (env, s::ss, stms) = let
606 :			val (s', env') = checkStmt (env, cxt, s)
607 :			in
608 :	jhr	81	chk (env', ss, s'::stms)
609 :	jhr	72	end
610 :			in
611 :	jhr	1116	(chk (blockScope env, stms, []), env)
612 :	jhr	72	end
613 :			| PT.S_Decl vd => let
614 :	jhr	1116	val (x, x', e) = checkVarDecl (env, cxt, Var.LocalVar, vd)
615 :	jhr	72	in
616 :	jhr	1116	checkForRedef (env, cxt, x);
617 :			(AST.S_Decl(AST.VD_Decl(x', e)), insertLocal(env, cxt, x, x'))
618 :	jhr	72	end
619 :			| PT.S_IfThen(e, s) => let
620 :	jhr	228	val (e', ty) = checkExpr (env, cxt, e)
621 :	jhr	81	val (s', _) = checkStmt (env, cxt, s)
622 :	jhr	72	in
623 :			(* check that condition has bool type *)
624 :			case ty
625 :			of Ty.T_Bool => ()
626 :	jhr	99	| _ => err(cxt, [S "condition not boolean type"])
627 :	jhr	72	(* end case *);
628 :			(AST.S_IfThenElse(e', s', AST.S_Block[]), env)
629 :			end
630 :			| PT.S_IfThenElse(e, s1, s2) => let
631 :	jhr	228	val (e', ty) = checkExpr (env, cxt, e)
632 :	jhr	81	val (s1', _) = checkStmt (env, cxt, s1)
633 :			val (s2', _) = checkStmt (env, cxt, s2)
634 :	jhr	72	in
635 :			(* check that condition has bool type *)
636 :			case ty
637 :			of Ty.T_Bool => ()
638 :	jhr	99	| _ => err(cxt, [S "condition not boolean type"])
639 :	jhr	72	(* end case *);
640 :			(AST.S_IfThenElse(e', s1', s2'), env)
641 :			end
642 :	jhr	228	| PT.S_Assign(x, e) => (case Env.findVar (#env env, x)
643 :	jhr	99	of NONE => err(cxt, [
644 :			S "undefined variable ", A x
645 :			])
646 :	jhr	72	| SOME x' => let
647 :	jhr	99	(* FIXME: check for polymorphic variables *)
648 :			val ([], ty) = Var.typeOf x'
649 :	jhr	228	val (e', ty') = checkExpr (env, cxt, e)
650 :	jhr	1975	(* check for promotion *)
651 :			val e' = (case coerceType(ty, ty', e')
652 :			of SOME e' => e'
653 :			| NONE => err(cxt, [
654 :			S "type of assigned variable ", A x,
655 :			S " does not match type of rhs\n",
656 :			S " expected: ", TY ty, S "\n",
657 :			S " but found: ", TY ty'
658 :			])
659 :			(* end case *))
660 :	jhr	72	in
661 :			(* check that x' is mutable *)
662 :			case Var.kindOf x'
663 :	jhr	511	of Var.StrandStateVar => ()
664 :			| Var.StrandOutputVar => ()
665 :	jhr	72	| Var.LocalVar => ()
666 :	jhr	99	| _ => err(cxt, [
667 :			S "assignment to immutable variable ", A x
668 :			])
669 :	jhr	72	(* end case *);
670 :			(AST.S_Assign(x', e'), env)
671 :			end
672 :			(* end case *))
673 :	jhr	1296	| PT.S_OpAssign(x, rator, e) => (case Env.findVar (#env env, x)
674 :			of SOME x' => let
675 :			val e1' = AST.E_Var x'
676 :			val ty1 = Var.monoTypeOf x'
677 :			val (e2', ty2) = checkExpr(env, cxt, e)
678 :	jhr	2133	val Env.PrimFun ovldList = Env.findFunc (#env env, rator)
679 :	jhr	1296	val (rhs, _) = resolveOverload (cxt, rator, [ty1, ty2], [e1', e2'], ovldList)
680 :			in
681 :			(AST.S_Assign(x', rhs), env)
682 :			end
683 :			| NONE => err(cxt, [S "undeclared variable ", A x, S " on lhs of ", A rator])
684 :			(* end case *))
685 :	jhr	511	| PT.S_New(strand, args) => let
686 :	jhr	228	val argsAndTys' = List.map (fn e => checkExpr(env, cxt, e)) args
687 :	jhr	81	val (args', tys') = ListPair.unzip argsAndTys'
688 :	jhr	72	in
689 :	jhr	228	case #scope env
690 :			of MethodScope => ()
691 :			| InitScope => ()
692 :	jhr	511	| _ => err(cxt, [S "invalid scope for new strand"])
693 :	jhr	228	(* end case *);
694 :	jhr	511	(* FIXME: check that strand is defined and has the argument types match *)
695 :			(AST.S_New(strand, args'), env)
696 :	jhr	72	end
697 :	jhr	228	| PT.S_Die => (
698 :			case #scope env
699 :	jhr	235	of MethodScope => ()
700 :			| _ => err(cxt, [S "\"die\" statment outside of method"])
701 :	jhr	228	(* end case *);
702 :			(AST.S_Die, env))
703 :			| PT.S_Stabilize => (
704 :			case #scope env
705 :	jhr	235	of MethodScope => ()
706 :			| _ => err(cxt, [S "\"stabilize\" statment outside of method"])
707 :	jhr	228	(* end case *);
708 :			(AST.S_Stabilize, env))
709 :	jhr	2133	| PT.S_Return e => let
710 :			val (e', ty) = checkExpr (env, cxt, e)
711 :			in
712 :			case #scope env
713 :			of FunctionScope ty' => (case coerceType(ty', ty, e')
714 :			of SOME e' => (AST.S_Return e', env)
715 :			| NONE => err(cxt, [
716 :			S "type of return expression does not match function's return type\n",
717 :			S " expected: ", TY ty', S "\n",
718 :			S " but found: ", TY ty
719 :			])
720 :			(* end case *))
721 :			| _ => err(cxt, [S "\"return\" statment outside of function"])
722 :			(* end case *)
723 :			end
724 :	jhr	1640	| PT.S_Print args => let
725 :			fun chkArg e = let
726 :			val (e', ty) = checkExpr (env, cxt, e)
727 :			in
728 :			if TU.isValueType ty
729 :			then ()
730 :			else err(cxt, [
731 :			S "expected value type in print, but found ", TY ty
732 :			]);
733 :			e'
734 :			end
735 :			val args' = List.map chkArg args
736 :			in
737 :			(AST.S_Print args', env)
738 :			end
739 :	jhr	70	(* end case *))
740 :
741 :	jhr	82	fun checkParams (env, cxt, params) = let
742 :			fun chkParam (env, cxt, param) = (case param
743 :	jhr	86	of PT.P_Mark m => chkParam (withEnvAndContext (env, cxt, m))
744 :	jhr	82	| PT.P_Param(ty, x) => let
745 :	jhr	511	val x' = Var.new(x, AST.StrandParam, checkTy (cxt, ty))
746 :	jhr	82	in
747 :	jhr	2149	(* FIXME: should use an empty bindings list for the parameters *)
748 :	jhr	1116	checkForRedef (env, cxt, x);
749 :			(x', insertLocal(env, cxt, x, x'))
750 :	jhr	82	end
751 :			(* end case *))
752 :			fun chk (param, (xs, env)) = let
753 :			val (x, env) = chkParam (env, cxt, param)
754 :			in
755 :			(x::xs, env)
756 :			end
757 :			in
758 :			List.foldr chk ([], env) params
759 :			end
760 :
761 :			fun checkMethod (env, cxt, meth) = (case meth
762 :	jhr	86	of PT.M_Mark m => checkMethod (withEnvAndContext (env, cxt, m))
763 :	jhr	82	| PT.M_Method(name, body) => let
764 :	jhr	228	val (body, _) = checkStmt(methodScope env, cxt, body)
765 :	jhr	82	in
766 :			AST.M_Method(name, body)
767 :			end
768 :			(* end case *))
769 :
770 :	jhr	511	fun checkStrand (env, cxt, {name, params, state, methods}) = let
771 :			(* check the strand parameters *)
772 :	jhr	82	val (params, env) = checkParams (env, cxt, params)
773 :	jhr	511	(* check the strand state variable definitions *)
774 :	jhr	2151	val (vds, hasOutput, env) = let
775 :			fun checkStateVar ((isOut, vd), (vds, hasOut, env)) = let
776 :	jhr	511	val kind = if isOut then AST.StrandOutputVar else AST.StrandStateVar
777 :	jhr	228	val (x, x', e') = checkVarDecl (env, cxt, kind, vd)
778 :	jhr	82	in
779 :	jhr	228	(* check that output variables have value types *)
780 :			if isOut andalso not(TU.isValueType(Var.monoTypeOf x'))
781 :			then err(cxt, [
782 :			S "output variable ", V x', S " has non-value type ",
783 :			TY(Var.monoTypeOf x')
784 :			])
785 :			else ();
786 :	jhr	1116	checkForRedef (env, cxt, x);
787 :	jhr	2151	(AST.VD_Decl(x', e')::vds, hasOut orelse isOut, insertLocal(env, cxt, x, x'))
788 :	jhr	82	end
789 :	jhr	2151	val (vds, hasOutput, env) = List.foldl checkStateVar ([], false, env) state
790 :	jhr	82	in
791 :	jhr	2151	(List.rev vds, hasOutput, env)
792 :	jhr	82	end
793 :	jhr	511	(* check the strand methods *)
794 :	jhr	82	val methods = List.map (fn m => checkMethod (env, cxt, m)) methods
795 :	jhr	1444	(* get the list of methods defined by the user *)
796 :			val methodNames = List.map (fn (AST.M_Method(name, _)) => name) methods
797 :	jhr	1116	(* if the stabilize method is not provided, add one *)
798 :	jhr	1640	val methods = if List.exists (fn StrandUtil.Stabilize => true | _ => false) methodNames
799 :	jhr	1116	then methods
800 :	jhr	1640	else methods @ [AST.M_Method(StrandUtil.Stabilize, AST.S_Block[])]
801 :	jhr	82	in
802 :	jhr	2151	(* FIXME: once there are global outputs, then it should be okay to have not strand outputs! *)
803 :			(* check that there is at least one output variable *)
804 :			if not hasOutput
805 :			then err(cxt, [S "strand ", A name, S " does not have any outputs"])
806 :			else ();
807 :	jhr	1444	(* FIXME: should check for duplicate method definitions *)
808 :	jhr	1640	if not(List.exists (fn StrandUtil.Update => true | _ => false) methodNames)
809 :	jhr	1116	then err(cxt, [S "strand ", A name, S " is missing an update method"])
810 :			else ();
811 :	jhr	511	AST.D_Strand{name = name, params = params, state = vds, methods = methods}
812 :	jhr	82	end
813 :
814 :	jhr	89	fun checkCreate (env, cxt, PT.C_Mark m) = checkCreate (withEnvAndContext (env, cxt, m))
815 :	jhr	511	| checkCreate (env, cxt, PT.C_Create(strand, args)) = let
816 :	jhr	228	val (args, tys) = checkExprList (env, cxt, args)
817 :	jhr	89	in
818 :	jhr	2151	(* FIXME: check args against strand definition *)
819 :	jhr	511	AST.C_Create(strand, args)
820 :	jhr	89	end
821 :
822 :	jhr	1116	fun checkIters (env0, cxt, iters) = let
823 :			(* check an iteration range specification from the initially clause. We do the checking
824 :			* of the expressions using env0, which does not have any of the iteration variables in
825 :			* it (the iteration is rectangular), but we also accumulate the iteration bindings,
826 :			* which are used to create the final environment for checking the create call.
827 :			*)
828 :			fun checkIter (env, cxt, PT.I_Mark m) = checkIter (withEnvAndContext (env, cxt, m))
829 :			| checkIter (env, cxt, PT.I_Range(x, e1, e2)) = let
830 :			val (e1', ty1) = checkExpr (env, cxt, e1)
831 :			val (e2', ty2) = checkExpr (env, cxt, e2)
832 :			val x' = Var.new(x, Var.LocalVar, Ty.T_Int)
833 :	jhr	89	in
834 :	jhr	1116	case (ty1, ty2)
835 :			of (Ty.T_Int, Ty.T_Int) => (AST.I_Range(x', e1', e2'), (x, x'))
836 :			| _ => err(cxt, [
837 :			S "range expressions must have integer type\n",
838 :			S " but found: ", TY ty1, S " .. ", TY ty2
839 :			])
840 :			(* end case *)
841 :	jhr	89	end
842 :	jhr	1116	fun chk ([], iters, bindings) =
843 :			(List.rev iters, List.foldl (fn ((x, x'), env) => insertLocal(env, cxt, x, x')) env0 bindings)
844 :			| chk (iter::rest, iters, bindings) = let
845 :			val (iter, binding) = checkIter (env0, cxt, iter)
846 :			in
847 :			chk (rest, iter::iters, binding::bindings)
848 :			end
849 :	jhr	89	in
850 :	jhr	1116	chk (iters, [], [])
851 :	jhr	89	end
852 :
853 :	jhr	71	fun checkDecl (env, cxt, d) = (case d
854 :	jhr	86	of PT.D_Mark m => checkDecl (withEnvAndContext (env, cxt, m))
855 :	jhr	1301	| PT.D_Input(ty, x, desc, optExp) => let
856 :			(* FIXME: need to do something with the description *)
857 :	jhr	71	val ty = checkTy(cxt, ty)
858 :			val x' = Var.new(x, Var.InputVar, ty)
859 :			val dcl = (case optExp
860 :	jhr	1301	of NONE => AST.D_Input(x', desc, NONE)
861 :	jhr	71	| SOME e => let
862 :	jhr	228	val (e', ty') = checkExpr (env, cxt, e)
863 :	jhr	71	in
864 :	jhr	1971	case coerceType (ty, ty', e')
865 :			of SOME e' => AST.D_Input(x', desc, SOME e')
866 :			| NONE => err(cxt, [
867 :			S "definition of ", V x', S " has wrong type\n",
868 :			S " expected: ", TY ty, S "\n",
869 :			S " but found: ", TY ty'
870 :			])
871 :			(* end case *)
872 :	jhr	71	end
873 :			(* end case *))
874 :			in
875 :	jhr	2050	(* check that input variables have valid types *)
876 :			if not(TU.isValueType ty orelse TU.isImageType ty)
877 :			then err(cxt, [S "input variable ", V x', S " has invalid type ", TY ty])
878 :	jhr	228	else ();
879 :	jhr	1116	checkForRedef (env, cxt, x);
880 :			(dcl, insertGlobal(env, cxt, x, x'))
881 :	jhr	71	end
882 :	jhr	72	| PT.D_Var vd => let
883 :	jhr	228	val (x, x', e') = checkVarDecl (env, cxt, Var.GlobalVar, vd)
884 :	jhr	72	in
885 :	jhr	1116	checkForRedef (env, cxt, x);
886 :			(AST.D_Var(AST.VD_Decl(x', e')), insertGlobal(env, cxt, x, x'))
887 :	jhr	72	end
888 :	jhr	2134	| PT.D_Func(ty, f, params, body) => let
889 :	jhr	2133	val ty' = checkTy(cxt, ty)
890 :			val (params', env') = checkParams (env, cxt, params)
891 :			val body' = (case body
892 :			of PT.FB_Expr e => let
893 :			val (e', ty) = checkExpr (env', cxt, e)
894 :			in
895 :			case coerceType(ty', ty, e')
896 :			of SOME e' => AST.S_Return e'
897 :			| NONE => err(cxt, [
898 :			S "type of function body does not match return type\n",
899 :			S " expected: ", TY ty', S "\n",
900 :			S " but found: ", TY ty
901 :			])
902 :			(* end case *)
903 :			end
904 :	jhr	2141	(* FIXME: we need to check that there is a return on all control-flow paths *)
905 :	jhr	2133	| PT.FB_Stmt s => #1(checkStmt(functionScope (env', ty'), cxt, s))
906 :			(* end case *))
907 :			val fnTy = Ty.T_Fun(List.map Var.monoTypeOf params', ty')
908 :			val f' = Var.new (f, AST.FunVar, fnTy)
909 :			in
910 :	jhr	2141	(* QUESTION: should we check for redefinition of the f? *)
911 :	jhr	2134	(AST.D_Func(f', params', body'), insertFunc(env, cxt, f, f'))
912 :	jhr	2133	end
913 :	jhr	511	| PT.D_Strand arg => (checkStrand(strandScope env, cxt, arg), env)
914 :	jhr	89	| PT.D_InitialArray(create, iterators) => let
915 :	jhr	228	val env = initScope env
916 :	jhr	89	val (iterators, env') = checkIters (env, cxt, iterators)
917 :			val create = checkCreate (env', cxt, create)
918 :			in
919 :			(AST.D_InitialArray(create, iterators), env)
920 :			end
921 :			| PT.D_InitialCollection(create, iterators) => let
922 :	jhr	228	val env = initScope env
923 :	jhr	89	val (iterators, env') = checkIters (env, cxt, iterators)
924 :			val create = checkCreate (env', cxt, create)
925 :			in
926 :			(AST.D_InitialCollection(create, iterators), env)
927 :			end
928 :	jhr	70	(* end case *))
929 :
930 :	jhr	1301	(* reorder the declarations so that the input variables come first *)
931 :			fun reorderDecls dcls = let
932 :			fun isInput (AST.D_Input _) = true
933 :			| isInput _ = false
934 :			val (inputs, others) = List.partition isInput dcls
935 :			in
936 :			inputs @ others
937 :			end
938 :
939 :	jhr	86	fun check errStrm (PT.Program{span, tree}) = let
940 :			val cxt = (errStrm, span)
941 :	jhr	1301	fun chk (env, [], dcls') = AST.Program(reorderDecls(List.rev dcls'))
942 :	jhr	81	| chk (env, dcl::dcls, dcls') = let
943 :	jhr	86	val (dcl', env) = checkDecl (env, cxt, dcl)
944 :	jhr	81	in
945 :			chk (env, dcls, dcl'::dcls')
946 :			end
947 :			in
948 :	jhr	1116	chk ({scope=GlobalScope, bindings=AtomMap.empty, env=Basis.env}, tree, [])
949 :	jhr	81	end
950 :	jhr	2149	handle TypeError => AST.Program[]
951 :	jhr	70
952 :	jhr	69	end

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