| 389 |
| _ => raise Unify (TYP(VARty(var), ty)) |
| _ => raise Unify (TYP(VARty(var), ty)) |
| 390 |
end |
end |
| 391 |
|
|
| 392 |
|
(* special handling of SCHEME tyvar instantiation: |
| 393 |
|
* ty must reduce to either a tyvar, var', in which case we unify |
| 394 |
|
* var and var' (in that order!), or |
| 395 |
|
* ty must reduce to a (basic) constant type, in which case ty |
| 396 |
|
* does not contain any type variables, and the occurrence check |
| 397 |
|
* (i.e. adjustType) is not necessary *) |
| 398 |
| instTyvar (var as ref(i as SCHEME eq),ty) = |
| instTyvar (var as ref(i as SCHEME eq),ty) = |
| 399 |
let val ty' = TU.headReduceType ty |
(case ty |
|
in case ty' |
|
| 400 |
of VARty var1 => unifyTyvars(var, var1) |
of VARty var1 => unifyTyvars(var, var1) |
| 401 |
| CONty(tyc,nil) => var := INSTANTIATED ty' |
(* because of asymmetric handling of SCHEME tyvars in |
| 402 |
(* valid potential resolution type. Could check |
* unifyTyvars -- here SCHEME must be first arg *) |
| 403 |
* for membership in allowed basic types (e.g. int, real, ...) *) |
| CONty(tyc,nil) => var := INSTANTIATED ty |
| 404 |
| _ => raise Unify(OVLD ty') |
| CONty(tyc,_) => (* nonnull arguments *) |
| 405 |
end |
(case TU.nullReduceType ty |
| 406 |
|
of VARty var1 => unifyTyvars(var, var1) |
| 407 |
|
| ty' as CONty(tyc,nil) => var := INSTANTIATED ty' |
| 408 |
|
(* valid potential resolution type. Could check more precisely |
| 409 |
|
* for membership in the allowed basic types |
| 410 |
|
* (e.g. int, real, ...) *) |
| 411 |
|
| WILDCARDty => () |
| 412 |
|
| _ => raise Unify(OVLD ty)) |
| 413 |
|
| WILDCARDty => () |
| 414 |
|
| _ => bug "instTyvar: SCHEME") |
| 415 |
|
|
| 416 |
| instTyvar (var as ref(i as LITERAL{kind,...}),ty) = |
| instTyvar (var as ref(i as LITERAL{kind,...}),ty) = |
| 417 |
(case TU.headReduceType ty |
(case TU.headReduceType ty |
| 418 |
of WILDCARDty => () |
of WILDCARDty => () |
| 419 |
| ty' => |
| ty' => |
| 420 |
if OLL.isLiteralTy(kind,ty') |
if OLL.isLiteralTy(kind,ty') |
| 421 |
then var := INSTANTIATED ty |
then var := INSTANTIATED (TU.nullReduceType ty) |
| 422 |
else raise Unify (LIT i)) (* could return the ty for error msg*) |
else raise Unify (LIT i)) (* could return the ty for error msg*) |
| 423 |
|
|
| 424 |
| instTyvar (ref(i as UBOUND _),ty) = |
| instTyvar (ref(i as UBOUND _),ty) = |
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