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| ID | Project | Category | View Status | Date Submitted | Last Update | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0000001 | mercury | Bug | public | 2007-09-17 11:18 | 2007-09-25 11:54 | ||||||||
| Reporter | obo | ||||||||||||
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| Priority | normal | Severity | minor | Reproducibility | always | ||||||||
| Status | acknowledged | Resolution | open | ||||||||||
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| Target Version | Fixed in Version | ||||||||||||
| Summary | 0000001: non-instructive error message: 'unused' mode requires explicit lambda expression | ||||||||||||
| Description | Hi. the attached code demonstrates a not quite instructive error message. While the predicate main2/2 compiles fine, main/2 does not, because I try to directly pass/curry an argument in 'unused' mode. One solution is to automatically infer the correct mode when currying, another is to make the error message more specific. Thanks, O. | ||||||||||||
| Additional Information | bug.m:019: In clause for `main(in, out)': bug.m:019: in argument 1 of call to predicate `call_int_modifier'/3: bug.m:019: mode error: variable `V_7' has instantiatedness `free', bug.m:019: expected instantiatedness for non-local variables of lambda goals bug.m:019: is `ground'. | ||||||||||||
| Tags | No tags attached. | ||||||||||||
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obo (reporter) 2007-09-17 11:56 |
Oh, in fact, changing main2 to something more useful -- i.e. passing the 'unused' value from outside (to pass type information) is prohibited for the same reasons: non-local vars ought to have ground inst. :- pred main2(mytype::unused, int::in, int::out) is det. main2(X, In, Out) :- call_int_modifier( (pred(I::in, O::out) is det :- add(X, I, O)), In, Out). I'm failing to work around it using (ground) type_desc: :- import_module type_desc. :- pred main3(mytype::unused, int::in, int::out) is det. main3(X, In, Out) :- XType = type_of(X), call_int_modifier( (pred(I::in, O::out) is det :- has_type(NewX, XType), add(NewX, I, O)), In, Out). bug.m:037: In clause for predicate `main3'/3: bug.m:037: in argument 1 of call to predicate `add'/3: bug.m:037: type error: variable `NewX' has type `(some [T] T)', bug.m:037: expected type was `(bug2.mytype)'. Is there a way to construct a free variable with a specific type? My guess is that this is the core restriction of the current mode checker... |
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juliensf (administrator) 2007-09-25 11:54 |
We will take a look at it. |
| Notes |
| Issue History |
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| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2007-09-17 11:18 | obo | New Issue | |
| 2007-09-17 11:18 | obo | File Added: bug.m | |
| 2007-09-17 11:56 | obo | Note Added: 0000001 | |
| 2007-09-25 11:54 | juliensf | Note Added: 0000005 | |
| 2007-09-25 11:54 | juliensf | Status | new => acknowledged |
| Issue History |