I have a problem with FriCAS 1.3.5 using records inside a function.
As an example consider the following code, where I define a record
type and simple constructor and accessor functions:-
(1) -> R ==> Record(a:Integer, b:Integer)
Type: Void
(2) -> makeR(x:Integer, y:Integer):R == [x,y]
Function declaration makeR : (Integer, Integer) -> Record(a: Integer
,b: Integer) has been added to workspace.
Type: Void
(3) -> getA(r:R):Integer == r.a
Function declaration getA : Record(a: Integer,b: Integer) -> Integer
has been added to workspace.
Type: Void
I then create a record and call my accessor function on it to retrieve
one of its components. This works as expected.
(4) -> r := makeR(2,3)
Compiling function makeR with type (Integer, Integer) -> Record(a:
Integer,b: Integer)
(4) [a = 2, b = 3]
Type: Record(a: Integer,b: Integer)
(5) -> getA(r)
Compiling function getA with type Record(a: Integer,b: Integer) ->
Integer
(5) 2
Type: PositiveInteger
Now I'll create a variable in the global workspace of the same name as
one of the selectors. This breaks things, but this is expected
because the selector name used in my accessor function is evaluated
(as described in the documentation).
(6) -> a := 0
Compiled code for getA has been cleared.
(6) 0
Type: NonNegativeInteger
(7) -> getA(r)
There are 29 exposed and 5 unexposed library operations named elt
having 2 argument(s) but none was determined to be applicable.
Use HyperDoc Browse, or issue
)display op elt
to learn more about the available operations. Perhaps
package-calling the operation or using coercions on the arguments
will allow you to apply the operation.
Cannot find a definition or applicable library operation named elt
with argument type(s)
Record(a: Integer,b: Integer)
NonNegativeInteger
<... snipped ...>
So now I try to create a more robust accessor function to stop this
happening (following guidance in the documentation):-
(7) -> getA2(r:R):Integer == r.'a
Function declaration getA2 : Record(a: Integer,b: Integer) ->
Integer has been added to workspace.
Type: Void
but when I use it I get the following error:-
(8) -> getA2(r)
>> System error:
The value
"a"
is not of type
LIST
and similarly with other variants I've tried, such as:-
getA3(r:R):Integer ==
local a
r.a
getA4(r:R):Integer ==
local avar
avar := 'a
r.avar
So, is this a bug? And if so, is there a workaround?
Thanks.
Paul
--
You received this message because you are subscribed to the Google Groups
"FriCAS - computer algebra system" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To view this discussion on the web visit
https://groups.google.com/d/msgid/fricas-devel/CAN8qZzTMY_Q58JN_H-jtnA_uXDpMMgroipWfxhHL7_ky2BTRUw%40mail.gmail.com.
