In normal circumstances the only Is
value which is available is the
computational identity A Is A
at all types A
.
In normal circumstances the only Is
value which is available is the
computational identity A Is A
at all types A
. These "self loops"
generate all of the behavior of equality and also ensure that at its
heart A Is B
is always just an identity relation.
Implementation note: all values of refl
return the same (private)
instance at whatever type is appropriate to save on allocations.
It can be convenient to convert a Predef.=:=
value into an Is
value.
It can be convenient to convert a Predef.=:=
value into an Is
value.
This is not strictly valid as while it is almost certainly true that
A =:= B
implies A Is B
it is not the case that you can create
evidence of A Is B
except via a coercion. Use responsibly.