Re: [racket-dev] A proposal for parametric opaque types in Typed Racket

[Alexander D. Knauth]

On Jan 30, 2015, at 3:59 PM, Alexis King lexi.lam...@gmail.com wrote:

 No, the typechecker can’t make any assumptions about the results of opaque 
 types. If you explicitly instantiate a Posn with the type Real, the 
 typechecker should only guarantee the result will be Real. Annotate the type 
 as (U 1 2), though, and obviously it would need to ensure that remains 
 invariant.

How about this program:
untyped.rkt:
#lang racket
(provide (all-defined-out))
(define (make-posn x y) (list 3 y)) ; bad
typed.rkt:
#lang typed/racket
; make Posn parametric
(define-type (Posn X Y) (List X Y))
(require/typed untyped.rkt
   [make-posn (All (X Y) X Y - (Posn X Y))])
(: p : (Posn Real Real))
(define p (make-posn 1 2))
This gives this error:
. . make-posn: broke its contract
  promised: X3
  produced: 3
  in: the car of
  the range of
  (parametric-/c
   (X3 Y4)
   (-*
(X3 Y4)
()
(values (cons/c X3 (cons/c Y4 g6)
  contract from: (interface for make-posn)
  blaming: (interface for make-posn)
   (assuming the contract is correct)
  at: …./typed.rkt:5.16

I think it’s a good thing that it checks that it actually gives you the value 
that you gave it, and not just something like 3 even if it happens to match the 
type you want.  And I think parametric opaque types should behave in a similar 
way, and to do that you would need the opaque value to be wrapped in another 
opaque structure, which would store either the contracts or the set of values 
that would pass the contracts or something like that.  

 
 On Jan 30, 2015, at 12:30, Alexander D. Knauth alexan...@knauth.org wrote:
 
 
 On Jan 30, 2015, at 1:53 PM, Alexis King lexi.lam...@gmail.com wrote:
 
 No, it doesn’t need to be wrapped in an opaque structure. Wrapping it in an 
 opaque structure would add a layer of indirection for absolutely no gain. 
 Remember, the value itself is already, by definition, opaque. The only way 
 typed code can manipulate the value is by passing it to other functions 
 imported via require/typed.
 
 This means that contracts only need to be generated wherever those 
 functions are called. This can be done without wrapping or unwrapping 
 anything because all the information required to generate those contracts 
 is known at expansion-time. The typechecker simply needs to insert the 
 relevant contracts at the relevant locations.
 
 Imagine a program like this:
 #lang typed/racket
 (require typed/lang/posn)
 (: p : (Posn Real Real)) ; I’m assuming Posn is parametric over 2 tvars, not 
 1
 (define p (posn 1 2))
 (: x : Real)
 (define x (posn-x p))
 As far as the type checker would check, it would check that the result of 
 posn-x is a Real, but I think that the runtime contract it should also check 
 that it returns 1, because posn could have been instantiated as (Posn 1 2).
 #lang typed/racket
 (require typed/lang/posn/mutable) ; like typed/lang/posn, but providing 
 mutation too
 (: p : (Posn Real Real))
 (define p (posn 1 2))
 (: x : Real)
 (define x (posn-x p))
 (set-posn-x! p 3)
 (: x2 : Real)
 (define x2 (posn-x p))
 Here, even though the type checker only cares that it’s a number, it should 
 check that x2 definition returns either 1 or 3, since both were provided as 
 x values for the posn p.
 
 For it to keep track of these at runtime, (and it would have to be runtime) 
 the contracts would have to be with the actual posn value in an opaque 
 structure, which would have contracts sort of like (new-∀/c) that would 
 check these things, although I don’t think it would have to wrap the inner 
 values, but just record them so that when posn-x is called on one of these 
 things, it checks that it was one of the values that was passed in to either 
 a constructor or setter function.  
 
 On Jan 30, 2015, at 07:27, Alexander D. Knauth alexan...@knauth.org 
 wrote:
  
 On Thu, Jan 29, 2015, at 09:03 PM, Alexis King wrote:
 It isn’t wrapped in an opaque structure. That wasn’t a part of my 
 proposal, and while I didn’t think of it until you brought it up, I still 
 think it’s unnecessary and doesn’t add any convenience.
  
 I think the opaque structures would be necessary for the kind of sharing 
 wrappers between functions that you describe just before section 2.1, 
 except that instead of the sub-values being wrapped on the untyped side, 
 the whole thing is wrapped on the typed side, and there is a contract that 
 wraps it and unwraps it when it goes from untyped to typed and back.  
  
 For parametric types, they have to also work if the type was constrained 
 to the exact set of values that were provided, which means that if you 
 provide two numbers, say 1 and 2, it has to return a posn with not just 
 any two numbers, but values of the type (U 1 2), since A could have been 
 constrained to (U 1 2).  So it has to be wrapped somehow, and I think 
 wrapping it on the typed side makes more sense.  
  
 Perhaps I’m not understanding you properly, but your “one-length string

Re: [racket-dev] A proposal for parametric opaque types in Typed Racket

[Alexander D. Knauth]

On Jan 30, 2015, at 1:53 PM, Alexis King lexi.lam...@gmail.com wrote:

 No, it doesn’t need to be wrapped in an opaque structure. Wrapping it in an 
 opaque structure would add a layer of indirection for absolutely no gain. 
 Remember, the value itself is already, by definition, opaque. The only way 
 typed code can manipulate the value is by passing it to other functions 
 imported via require/typed.
 
 This means that contracts only need to be generated wherever those functions 
 are called. This can be done without wrapping or unwrapping anything because 
 all the information required to generate those contracts is known at 
 expansion-time. The typechecker simply needs to insert the relevant contracts 
 at the relevant locations.

Imagine a program like this:
#lang typed/racket
(require typed/lang/posn)
(: p : (Posn Real Real)) ; I’m assuming Posn is parametric over 2 tvars, not 1
(define p (posn 1 2))
(: x : Real)
(define x (posn-x p))
As far as the type checker would check, it would check that the result of 
posn-x is a Real, but I think that the runtime contract it should also check 
that it returns 1, because posn could have been instantiated as (Posn 1 2).
#lang typed/racket
(require typed/lang/posn/mutable) ; like typed/lang/posn, but providing 
mutation too
(: p : (Posn Real Real))
(define p (posn 1 2))
(: x : Real)
(define x (posn-x p))
(set-posn-x! p 3)
(: x2 : Real)
(define x2 (posn-x p))
Here, even though the type checker only cares that it’s a number, it should 
check that x2 definition returns either 1 or 3, since both were provided as x 
values for the posn p.

For it to keep track of these at runtime, (and it would have to be runtime) the 
contracts would have to be with the actual posn value in an opaque structure, 
which would have contracts sort of like (new-∀/c) that would check these 
things, although I don’t think it would have to wrap the inner values, but just 
record them so that when posn-x is called on one of these things, it checks 
that it was one of the values that was passed in to either a constructor or 
setter function.  

 On Jan 30, 2015, at 07:27, Alexander D. Knauth alexan...@knauth.org wrote:
  
 On Thu, Jan 29, 2015, at 09:03 PM, Alexis King wrote:
 It isn’t wrapped in an opaque structure. That wasn’t a part of my proposal, 
 and while I didn’t think of it until you brought it up, I still think it’s 
 unnecessary and doesn’t add any convenience.
  
 I think the opaque structures would be necessary for the kind of sharing 
 wrappers between functions that you describe just before section 2.1, 
 except that instead of the sub-values being wrapped on the untyped side, the 
 whole thing is wrapped on the typed side, and there is a contract that wraps 
 it and unwraps it when it goes from untyped to typed and back.  
  
 For parametric types, they have to also work if the type was constrained to 
 the exact set of values that were provided, which means that if you provide 
 two numbers, say 1 and 2, it has to return a posn with not just any two 
 numbers, but values of the type (U 1 2), since A could have been constrained 
 to (U 1 2).  So it has to be wrapped somehow, and I think wrapping it on the 
 typed side makes more sense.  
  
 Perhaps I’m not understanding you properly, but your “one-length string” 
 idea sounds like it has little to do with this opaque type problem and more 
 to do with the fact that you want refinement types in Typed Racket. I do, 
 too! But I don’t think hacking the opaque type system is going to help you 
 with that.
  
 Well, yeah, refinement types would be the real solution for this 
 particular example, but if I do want to constrain it to strings of length 1, 
 opaque types are the only option for now, and they actually work fine.  My 
 point was you couldn't do this type of thing with the opaque structures and 
 you would probably get weird errors if you tried.  (See below because there 
 might be a solution?)
  
 (Also, as for the box example, I’m actually a little surprised that doesn’t 
 contract error. Seems like a bug to me, but perhaps I’m missing some 
 idiosyncrasies of the type system. Either way, it’s precisely that kind of 
 craziness I was referring to when I compared casting parametric opaque 
 types to casting mutable types.)
  
 There is a bug report for it here, and the solution proposed by Sam 
 Tobin-Hochstadt would be for cast to generate 2 contracts, one for the 
 original type, one for the new type, but that never got implemented.  
 http://bugs.racket-lang.org/query/?cmd=viewpr=13626
  
 Actually now that I think about it the two-contract solution might be able 
 to solve the previous problem, since the original contract could unwrap the 
 value before it is passed to the new contract?  I'm not sure though.  The 
 value inside the cast would be from the typed side, then it is passed 
 through the orig contract as if it were going to the typed side,

This was a typo, I meant to say “as if it were going

Re: [racket-dev] A proposal for parametric opaque types in Typed Racket

[Alexander D. Knauth]

On Jan 29, 2015, at 11:34 PM, Alexis King lexi.lam...@gmail.com wrote:

 But the problem is that if it’s an opaque type then it can’t unwrap it once 
 the value is returned from make-posn.
 
 Yes, that’s precisely the problem. Your point about implementing everything 
 as single-valued structs on the typed side is an interesting one, though I 
 don’t think it ultimately solves any problems. The fact that the typed side 
 knows nothing about the contents of the value is what makes this such a 
 tricky problem.
 
 As for this:
 
 But then you couldn’t do any operations on it except those that you use 
 import with require/typed, right?
 
 That’s completely correct. That’s why it’s “opaque.”
 
 And what happens if you use cast on one of these things?
 
 That’s a little more interesting. Using cast on an object of this type would 
 never fail (unless, of course, it didn’t actually satisfy the basic posn? 
 predicate), but it would possibly introduce failures in the future since it 
 would affect the contracts generated for posn-x and posn-y, for example.
 
 To make that more clear, casting a (Posn Real) to a (Posn String) would work 
 fine until you tried to call posn-x on the instance, in which case it would 
 raise a contract error. Note that this isn’t really any different from 
 casting mutable data types.

But if it were wrapped in an opaque structure, then that structure wouldn’t 
satisfy the posn? predicate, unless of course the posn? predicate has a 
contract that unwraps it.  So all of the operations on it would have to have 
contracts that would unwrap it.  This might actually make sense if the type is 
meant to be actually opaque, but if it’s an opaque type that represents a 
normal non-opaque value, then it will still work as an opaque type, but it 
won’t be a normal non-opaque value anymore on the typed side.  

But the reason I asked about cast was because normally I can use cast with a 
value that has an opaque type, but it’s wrapped on the typed side in this 
opaque structure, then the contracts on the cast would see this opaque 
structure instead of the actual value.  

I’m thinking of an opaque typed representing a string with length 1, which I 
can use as long as I use either (cast x String) or (assert x string?) whenever 
I pass it to a string operation.  But if it were an opaque type, I don’t think 
I could do that.  There could be a 1string-string function that could take one 
of these 1strings and convert it to a string, but that seems like it should be 
unnecessary, but made necessary by this opaque structure thing.  

And for “this isn’t really any different from casting mutable data types,” look 
at this:
#lang typed/racket
(: b : (Boxof Number))
(define b (box 1))
(set-box! (cast b (Boxof (U Number String))) I am a string)
(ann (unbox b) Number) ;I am a string” ; not a contract error


 
 On Jan 29, 2015, at 20:20, Alexander D. Knauth alexan...@knauth.org wrote:
 
 Furthermore, even if the wrappers were shared between functions, untyped 
 code would recieved wrapped values, which would render them quite useless.
 
 If it’s not an opaque type, but something like a list, then this works, and 
 the untyped code receiving wrapped values isn’t a problem here:
 #lang typed/racket
 ; make Posn parametric
 (define-type (Posn A) (List A A))
 (provide Posn)
 (require/typed/provide
  untyped.rkt
  [make-posn (All (A) A A - (Posn A))]
  [posn-x (All (A) (Posn A) - A)]
  [posn-y (All (A) (Posn A) - A)]
  [real-posn? [(Posn Any) - Boolean]])
  (define p (make-posn 1 2))
 (make-posn #A6 #A6) ; a printf that I put in make-posn from “untyped.rkt
  p
 - : (Listof Positive-Byte) [more precisely: (List Positive-Byte 
 Positive-Byte)]
 '(1 2) ; unwrapped
  (posn-x p)
 - : Integer [more precisely: Positive-Byte]
 1
  (posn-y p)
 - : Integer [more precisely: Positive-Byte]
 2
  (real-posn? p)
 - : Boolean
 #t
 
 Even though for a short time it's wrapped, it’s unwrapped as soon as 
 make-posn returns, and then after that if it flows into untyped code again 
 it’s not wrapped and functions like real-posn? work fine.  
 
 But the problem is that if it’s an opaque type then it can’t unwrap it once 
 the value is returned from make-posn.
 
 And I don’t think parametric opaque types could solve this unless all posns 
 themselves were wrapped with an opaque struct on the typed side, which I 
 guess does make sense now that I think about it.  But then you couldn’t do 
 any operations on it except those that you use import with require/typed, 
 right?  Or not?  And what happens if you use cast on one of these things?
 
 
 On Jan 29, 2015, at 9:25 PM, Alexis King lexi.lam...@gmail.com wrote:
 
 I recently ran into a problem in which opaque types (types imported from 
 untyped code) cannot by parameterized by Typed Racket. I initially 
 encountered this problem in my attempt to port 2htdp/image to TR.
 
 After some further consideration, I’m interested in adding support to make 
 something like this possible, which

Re: [racket-dev] A proposal for parametric opaque types in Typed Racket

[Alexander D. Knauth]

Um, for this:
(module typed typed/racket/base
(provide (struct-out Foo))
(struct [A] Foo ([x : A] [y : A]) #:transparent))

(Foo a 'b)
Should be fine because Foo could be instantiated at the type (U String Symbol).

On Jan 29, 2015, at 9:25 PM, Alexis King lexi.lam...@gmail.com wrote:

 I recently ran into a problem in which opaque types (types imported from 
 untyped code) cannot by parameterized by Typed Racket. I initially 
 encountered this problem in my attempt to port 2htdp/image to TR.
 
 After some further consideration, I’m interested in adding support to make 
 something like this possible, which would certainly have additional benefits 
 beyond this specific use-case. I’ve outlined my proposal here:
 http://lexi-lambda.github.io/racket-parametric-opaque-types/
 
 Any feedback, suggestions, or advice would be appreciated, especially from 
 those who are familiar with Typed Racket’s internals.
 
 Thank you,
 Alexis
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Re: [racket-dev] A proposal for parametric opaque types in Typed Racket

[Alexander D. Knauth]

Furthermore, even if the wrappers were shared between functions, untyped code 
would recieved wrapped values, which would render them quite useless.

If it’s not an opaque type, but something like a list, then this works, and the 
untyped code receiving wrapped values isn’t a problem here:
#lang typed/racket
; make Posn parametric
(define-type (Posn A) (List A A))
(provide Posn)
(require/typed/provide
 untyped.rkt
 [make-posn (All (A) A A - (Posn A))]
 [posn-x (All (A) (Posn A) - A)]
 [posn-y (All (A) (Posn A) - A)]
 [real-posn? [(Posn Any) - Boolean]])
 (define p (make-posn 1 2))
(make-posn #A6 #A6) ; a printf that I put in make-posn from “untyped.rkt
 p
- : (Listof Positive-Byte) [more precisely: (List Positive-Byte Positive-Byte)]
'(1 2) ; unwrapped
 (posn-x p)
- : Integer [more precisely: Positive-Byte]
1
 (posn-y p)
- : Integer [more precisely: Positive-Byte]
2
 (real-posn? p)
- : Boolean
#t

Even though for a short time it's wrapped, it’s unwrapped as soon as make-posn 
returns, and then after that if it flows into untyped code again it’s not 
wrapped and functions like real-posn? work fine.  

But the problem is that if it’s an opaque type then it can’t unwrap it once the 
value is returned from make-posn.

And I don’t think parametric opaque types could solve this unless all posns 
themselves were wrapped with an opaque struct on the typed side, which I guess 
does make sense now that I think about it.  But then you couldn’t do any 
operations on it except those that you use import with require/typed, right?  
Or not?  And what happens if you use cast on one of these things?


On Jan 29, 2015, at 9:25 PM, Alexis King lexi.lam...@gmail.com wrote:

 I recently ran into a problem in which opaque types (types imported from 
 untyped code) cannot by parameterized by Typed Racket. I initially 
 encountered this problem in my attempt to port 2htdp/image to TR.
 
 After some further consideration, I’m interested in adding support to make 
 something like this possible, which would certainly have additional benefits 
 beyond this specific use-case. I’ve outlined my proposal here:
 http://lexi-lambda.github.io/racket-parametric-opaque-types/
 
 Any feedback, suggestions, or advice would be appreciated, especially from 
 those who are familiar with Typed Racket’s internals.
 
 Thank you,
 Alexis
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Re: [racket-dev] In Typed Racket, struct declarations do not work in an internal definition context

[Alexander D. Knauth]

There’s a bug report about this here:
http://bugs.racket-lang.org/query/?cmd=viewpr=14524
Though I notice it gives a different error message now.
But why should structure type declarations being a module-wide construct?
Internal function definitions work, and internal type definitions work, so why 
shouldn’t internal structure definitions?


On Jan 22, 2015, at 3:57 PM, Alexis King lexi.lam...@gmail.com wrote:

 Simple enough. This works:
 
 #lang racket
 
 (define (make-me-a-struct)
   (struct foo ())
   (foo))
 
 (make-me-a-struct) ; = #foo
 
 This does not:
 
 #lang typed/racket
 
 (define (make-me-a-struct)
   (struct foo ())
   (foo)) ; error: cannot apply a function with unknown arity
 
 (make-me-a-struct)
 
 This problem makes sense. Type declarations seem to be a module-wide 
 construct, so a type that should be scoped to a single function doesn’t work. 
 I’m running into this issue when trying to create an executable struct using 
 define-struct/exec from within a macro, which doesn’t work due to this 
 particular problem.
 
 I can work around this in a variety of ways—I can extract this into an 
 untyped module and use require/typed, I can use vectors to “fake” structs and 
 provide an appropriate interface, etc. Still, I wonder if there are any plans 
 to resolve this type of problem? Since it seems to be an issue with how TR 
 handles types at its core, I’m not even sure how feasible it would be.
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Re: [racket-dev] question, issue(?) with the scope of identifiers passed into define-syntax-rule

[Alexander D. Knauth]

But I think it’s important that it doesn’t use gensym or something like that, 
it uses syntax-marks, which means you can break these lexical scoping rules if 
you want/need to by using either syntax-local-introduce or datum-syntax:

#lang racket
(require syntax/parse/define)
(define-simple-macro (with-tables stem body ...)
  #:with table-author-id (syntax-local-introduce #'table-author)
  (let([table-publication (string-append stem _publication)]
   [table-author-id (string-append stem _author)]
   [table-bridge-publication-author (string-append stem 
_bridge_publication_author)]
   [table-unique-counters (string-append stem _unique_counters)]
   )
body ...
))
(with-tables x table-author) ;”x_author


On Jan 15, 2015, at 9:23 PM, Alexander McLin alex.mc...@gmail.com wrote:

 Warning I am still a Racket intermediate user but I've been studying 
 syntactic extensions a lot the past several months.
 
 The problem here is macros in Racket have lexical scope just like procedures, 
 they are hygienic macros. The identifiers you introduced in the with-tables 
 macro only exist or refer to other bindings in the same lexical scope as 
 where you originally wrote the macro.
 
 When you invoke the macro and pass in table-author, even though it is spelled 
 the same as the identifier you wrote in the macro definition, they are not 
 the same. When the macro expands, hygiene is implemented by renaming all 
 identifiers in the macro to unique non-clashing symbols that don't conflict 
 with others existing in the scope the macro is expanding in.
 
 The table-author identifier in the macro in the let form is renamed to 
 something different like g6271 or something along those lines.
 
 Furthermore, you need to be careful about what you mean by evaluation. In the 
 presence of macros, you have the concept of syntax phase(or compile-time or 
 expand-time) evaluation versus run-time evaluation. When the macro is 
 expanding, it does it thing, processing the original syntax into the new 
 piece of syntax that replaces what was there previously such as (with-tables 
 x table-author) which is then finally evaluated during run-time.
 
 (with-tables x table-author) will expand into something looking similar to 
 the following, just to give you an idea of what macro expansion looks like:
 
 (let ((g6191 (string-append x _publication))
(g6271 (string-append x _author))
(g6369 (string-append x _bridge_publication_author))
(g6445 (string-append x _unique_counters)))
table-author)
 
 Note that the original table-author identifier has been replaced by a 
 different identifier that still has the same binding you originally defined.
 
 The table-author identifier you passed to the macro gets inserted in the body 
 position and then the expanded code is evaluated at run-time and of course 
 gives you a run-time error since table-author does not refer to anything and 
 thus when it's evaluated, it is recognized as an undefined identifier.
 
 (with-tables x hello) works because what you get in return is:
 
 (let ((g6191 (string-append x _publication))
(g6271 (string-append x _author))
(g6369 (string-append x _bridge_publication_author))
(g6445 (string-append x _unique_counters)))
hello)
 
 hello is just a self-evaluating string giving you back hello from within 
 the let form.
 
 On Thu, Jan 15, 2015 at 12:12 AM, Thomas Lynch 
 thomas.ly...@reasoningtechnology.com wrote:
 I have a simple syntax rule:
 
   Welcome to Racket v5.2.1.
   racket@ (define-syntax-rule (with-tables stem body ...)
 (let(
   [table-publication (string-append stem _publication)]
   [table-author (string-append stem _author)]
   [table-bridge-publication-author (string-append stem 
 _bridge_publication_author)]
   [table-unique-counters (string-append stem _unique_counters)]
   )
   body ...
   ))
 
 Which works fine when I don't reference the environment defined by the let:
 
   racket@
   racket@ (with-tables x hello)
   hello
 
 
 However when I pass it an identifier corresponding to one of the variables 
 defined in the let:
 
   racket@ (with-tables x table-author)
   reference to undefined identifier: table-author
   stdin::1167: table-author
 
 The identifier passed in doesn't seem to be part of the local let context, 
 but carried in a different context, or perhaps it was evaluated as an 
 operand.  I didn't expect either of those.  Can someone point me at a 
 description of the expected behavior, or give me a tip here on what is 
 happening and why.
 
 ... in Wolfram language there is a 'Hold' operator for situations like this.  
 Apparently inside the macro we have to do some evaluation to handle the work 
 of the macro,  is that why the operand is evaluated? 
 
 Thanks in advance for explaining the evaluation/context model here.
 
 Thomas 
 
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Re: [racket-dev] parse errors in types, poly-dots cause me headaches

[Alexander D. Knauth]

In terms of bugs, it’s probably related to this problem with call-with-values 
and poly-dots:
#lang typed/racket
(: f : (All (a ...) [(- (values Any ... a)) - Void]))
(define (f g)
  (call-with-values g void))
;=
. . ../../Applications/Racket 
v6.1.1/share/pkgs/typed-racket-lib/typed-racket/typecheck/tc-app/tc-app-values.rkt:22:4:
 match: no matching clause for (tc-results '() (cons Any 'a))

On Nov 18, 2014, at 11:54 AM, Matthias Felleisen matth...@ccs.neu.edu wrote:

 
 On Nov 18, 2014, at 11:34 AM, Sam Tobin-Hochstadt sa...@cs.indiana.edu 
 wrote:
 
 On Tue, Nov 18, 2014 at 10:45 AM, Matthias Felleisen
 matth...@ccs.neu.edu wrote:
 
 It's quite possible that this is Eli's bug again, but boy this causes 
 headaches:
 
 Type Checker: parse error in type;
 type variable must be used with ...
 variable: Y in: Y
 
 And it points precisely to where Y is followed by ...
 
 The problem here is that you're using -* without using the syntax of
 -*.  Fortunately, this program doesn't need -* at all.
 
 Unfortunately, I don't know how to make this function type check yet,
 but I'll keep playing with it.
 
 
 Are you blaming the victim here? Please run what I send out and experience 
 how the type checker barfs on you. This is a bug report. 
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Re: [racket-dev] Help with build failed error message

[Alexander D. Knauth]

Ok it turns out I had done (syntax/loc stx #’template) instead of (syntax/loc 
stx template) and somehow that seems to have triggered some kind of infinite 
recursive loop or something.  

But I fixed it and got another error that makes no sense at all.

It seems like somehow a struct constructor is returning #f.  

raco setup: 0 making: pkgs/racket-test/tests/future
struct-type/sc: broke its contract
  promised: static-contract?
  produced: #f
  in: the range of
  (- any/c static-contract?)
  contract from: 
  
pkgs/typed-racket-lib/typed-racket/static-contracts/combinators/struct.rkt
  blaming: 
pkgs/typed-racket-lib/typed-racket/static-contracts/combinators/struct.rkt
   (assuming the contract is correct)
  at: 
pkgs/typed-racket-lib/typed-racket/static-contracts/combinators/struct.rkt:19.5
(lines 1217-1227 of https://travis-ci.org/AlexKnauth/racket/jobs/30418536)
Where struct-type/sc is defined like this in 
pkgs/typed-racket-lib/typed-racket/static-contracts/combinators/struct.rkt:
(struct struct-type/sc combinator ()
  #:transparent
  #:property prop:combinator-name struct-type/sc
  #:methods gen:sc
[(define (sc-map v f)
   (match v
 [(struct-type/sc args)
  (struct-type/sc (map (λ (a) (f a 'covariant)) args))]))
 (define (sc-traverse v f)
   (match v
 [(struct-type/sc args)
  (for-each (λ (a) (f a 'covariant)) args)
  (void)]))
 (define (sc-contract v f)
   (match v
 [(struct-type/sc args)
  #`(struct-type/c #f)]))
 (define (sc-constraints v f)
   (match v
 [(struct-type/sc args) (simple-contract-restrict 'chaperone)]))])

I have no idea what to do.  



On Jul 20, 2014, at 2:15 AM, Matthew Flatt mfl...@cs.utah.edu wrote:

 Killed means that the OS terminated the `racket/racket3m` process
 from the outside. For example, the process may have exceeded a
 memory-use limit.
 
 At Sat, 19 Jul 2014 20:25:24 -0400, Alexander D. Knauth wrote:
 I made a fork of the racket repo and committed some changes in a topic 
 branch, 
 but I got this:
 make[8]: Leaving directory 
 `/home/travis/build/AlexKnauth/racket/racket/src/build'
 make[7]: Leaving directory 
 `/home/travis/build/AlexKnauth/racket/racket/src/build'
 make[6]: Leaving directory 
 `/home/travis/build/AlexKnauth/racket/racket/src/build'
 racket/racket3m -X /home/travis/build/AlexKnauth/racket/racket/collects -G 
 /home/travis/build/AlexKnauth/racket/racket/etc -G 
 /home/travis/build/AlexKnauth/racket/build/config -N raco -l- setup  
 --no-user -j 2  
 raco setup: bootstrapping from source...
 Killed
 make[5]: *** [install-3m] Error 137
 make[5]: Leaving directory 
 `/home/travis/build/AlexKnauth/racket/racket/src/build'
 make[4]: *** [install] Error 2
 make[4]: Leaving directory 
 `/home/travis/build/AlexKnauth/racket/racket/src/build'
 make[3]: *** [base] Error 2
 make[3]: Leaving directory `/home/travis/build/AlexKnauth/racket'
 make[2]: *** [plain-in-place] Error 2
 make[2]: Leaving directory `/home/travis/build/AlexKnauth/racket'
 make[1]: *** [cpus-in-place] Error 2
 make[1]: Leaving directory `/home/travis/build/AlexKnauth/racket'
 make: *** [in-place] Error 2
 The command make CPUS=2 PKGS=racket-test db-test unstable-flonum-lib 
 net-test exited with 2.
 (lines 812-830 of https://travis-ci.org/AlexKnauth/racket/jobs/30368892)
 
 What does this mean?
 
 What does the “Killed” mean?
 And what is error 137?
 
 _
  Racket Developers list:
  http://lists.racket-lang.org/dev

_
  Racket Developers list:
  http://lists.racket-lang.org/dev

[racket-dev] Help with build failed error message

[Alexander D. Knauth]

I made a fork of the racket repo and committed some changes in a topic branch, 
but I got this:
make[8]: Leaving directory 
`/home/travis/build/AlexKnauth/racket/racket/src/build'
make[7]: Leaving directory 
`/home/travis/build/AlexKnauth/racket/racket/src/build'
make[6]: Leaving directory 
`/home/travis/build/AlexKnauth/racket/racket/src/build'
racket/racket3m -X /home/travis/build/AlexKnauth/racket/racket/collects -G 
/home/travis/build/AlexKnauth/racket/racket/etc -G 
/home/travis/build/AlexKnauth/racket/build/config -N raco -l- setup  
--no-user -j 2  
raco setup: bootstrapping from source...
Killed
make[5]: *** [install-3m] Error 137
make[5]: Leaving directory 
`/home/travis/build/AlexKnauth/racket/racket/src/build'
make[4]: *** [install] Error 2
make[4]: Leaving directory 
`/home/travis/build/AlexKnauth/racket/racket/src/build'
make[3]: *** [base] Error 2
make[3]: Leaving directory `/home/travis/build/AlexKnauth/racket'
make[2]: *** [plain-in-place] Error 2
make[2]: Leaving directory `/home/travis/build/AlexKnauth/racket'
make[1]: *** [cpus-in-place] Error 2
make[1]: Leaving directory `/home/travis/build/AlexKnauth/racket'
make: *** [in-place] Error 2
The command make CPUS=2 PKGS=racket-test db-test unstable-flonum-lib 
net-test exited with 2.
(lines 812-830 of https://travis-ci.org/AlexKnauth/racket/jobs/30368892)

What does this mean?

What does the “Killed” mean?
And what is error 137?

_
  Racket Developers list:
  http://lists.racket-lang.org/dev