[Ur] Building site templates

[James Parker]

I've tried xml, body, and xhtml. Is there some other type I can try? If I simply define sidebar inside template, the project will compile and run correctly.

The source is available here if it's helpful:

https://github.com/jprider63/UMDTalks

Here's the full error message:

/home/james/Projects/UMDTalks/common.urs:4:32-4:35: Wrong kind
Constructor:  Basis.xml
  Have kind:  {Unit} -> {Type} -> {Type} -> Type
  Need kind:  Type
Incompatible kinds
Kind 1:  {Unit} -> {Type} -> {Type} -> Type
Kind 2:  Type
/home/james/Projects/UMDTalks/common.ur:10:0-50:0: Constructor unification failure in signature matching:
 Have: 
val template :
 ((Basis.option Basis.string) ->
   ((Basis.xml ([#Body = ()]) <UNIF:U0::{Type}> <UNIF:U2::{Type}>) ->
     <UNIF:F::Type -> Type>
      (Basis.xml ([#Html = ()]) <UNIF:U0::{Type}> <UNIF:U2::{Type}>)))
 Need: 
val template :
 ((Basis.option Basis.string) ->
   (Basis.xml ->
     Basis.transaction (Basis.xml ([#Html = ()]) ([]) ([]))))
Con 1: 
((Basis.option Basis.string) ->
  ((Basis.xml ([#Body = ()]) <UNIF:U0::{Type}> <UNIF:U2::{Type}>) ->
    <UNIF:F::Type -> Type>
     (Basis.xml ([#Html = ()]) <UNIF:U0::{Type}> <UNIF:U2::{Type}>)))
Con 2: 
((Basis.option Basis.string) ->
  (Basis.xml ->
    Basis.transaction (Basis.xml ([#Html = ()]) ([]) ([]))))
Incompatible constructors
Have:  Basis.xml ([#Body = ()]) <UNIF:U0::{Type}> <UNIF:U2::{Type}>
Need:  Basis.xml
/home/james/Projects/UMDTalks/umdtalks.ur:33:1-34:38: Unification failure
Expression: 
fn sidebar : Basis.xml =>
 Common.template (Some [Basis.string] "test") sidebar
  Have con: 
(Basis.xml -> Basis.transaction (Basis.xml ([#Html = ()]) ([]) ([])))
  Need con: 
((Basis.xml (([#Body = ()]) ++ <UNIF:U10::{Unit}>) <UNIF:U2::{Type}>
   ([])) -> <UNIF:S::Type -> Type> <UNIF:U::Type>)
Incompatible constructors
Have:  Basis.xml
Need: 
Basis.xml (([#Body = ()]) ++ <UNIF:U10::{Unit}>) <UNIF:U2::{Type}>

I've been finding it somewhat difficult to understand what the error messages are looking for. Are the type inferencing messages a result of the wrong signature type?

Thanks,

JP

On Dec 6, 2011, at 8:40 AM, Adam Chlipala wrote:

> James Parker wrote:
>>         title'<- return (case title of
>>                 | None =>  "UMDTalks"
>>                 | Some t =>  String.append t " - UMDTalks"
>>   
> 
> Here I would recommend the infix operator [^] instead of [String.append].
> 
>> My current function signature is:
>> 
>> val template : option string ->  xml ->  transaction page
>> 
>> I believe the problem is in the signature. I guess what is the proper type for the second parameter?
>>   
> 
> You probably want [xbody] instead of [xml].  You can look in lib/ur/basis.urs to see the kinds of all the built-in constructors.
> 
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