Hi,
if this is not the correct place for sending FricasUG fix requirements, please
excuse me and let me now.
RiCCardo
[FricasUG] FIXME: sec 2.5.2 "Union-s with selectors" pag 96
"Note that case uses the selector name as its right-hand argument. If you
accidentally use the branch
type on the right-hand side of case, false will be returned. Now it returns
error."
(1) -> U := Union(i:Integer, s:String)
(1) Union(i: Integer,s: String)
Type: Type
(2) -> x:U := "bam"
(2) "bam"
Type: Union(s: String,...)
(3) -> x case Integer
>> Error detected within library code:
upcase: bad Union form
(3) -> x case String
>> Error detected within library code:
upcase: bad Union form
(3) -> x case i
(3) false
Type: Boolean
(4) -> x case s
(4) true
The statements above prove that the fricasUG must be fixed.
=== Feature suggestion for Union-s ===
I must say that I would find more natural (and maybe it would have simpler code)
to have the predicates
x case Integer
x case String
as for non-selector Union-s and to use selectors only to get the values
x.i
x.s
with "failed" instead of a coerce error when the inappropriate selector is
called: relying on the fact that a coercion might rescue you if the value branch does not
correspond to the selector looks somehow hackish.
(5) -> x.i
>> Error detected within library code:
"bam" of mode Union(i: Integer,s: String) cannot be coerced to mode Integer
(5) -> x.s
(5) "bam"
Type: String
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