By prefacing [Monad.mapR] with [@], you have requested that type class
arguments be passed explicitly. Membership in the class [monad] is an
example of such an argument, and you can see it early in the type of
[mapR] (and it appears first in the error message). That argument
should go first, before [[id]]. Just put an underscore in that position
and it should work.
Gergely Buday wrote:
I would like to fix type constraints for using Monad.mapR so that I
need not pass them when using for creating sources of values. I do not
understand what this error message say, let alone fix the bug. How
should I fix my code?
- Gergely
$ urweb mapr
/home/gergoe/local/sandbox/sandbox/mapr.ur:2:5-2:16: Expression is not
a constructor function
Expression: Monad.mapR[[<UNIF:R>]] [<UNIF:A::Type -> Type>]
Type:
((Basis.monad<UNIF:A::Type -> Type>) ->
tf ::<UNIF:R> -> Type ->
tr ::<UNIF:R> -> Type ->
((nm :: Name ->
t ::<UNIF:R> -> ((tf t) -> <UNIF:A::Type -> Type+4> (tr t)))
->
r ::: {<UNIF:R>} ->
((Top.folder[[<UNIF:R>]] r) ->
($(map tf r) -> <UNIF:A::Type -> Type+3> $(map tr r)))))
$ head -3 mapr.ur
fun sourceRecord [ r ::: {Type} ] (fl : folder r) (record : $r) :
(transaction $(map source r)) =
@Monad.mapR [id] [source] fl (fn [nm :: Name] [t :: Type] =>
source ) fl record
_______________________________________________
Ur mailing list
[email protected]
http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
