The >
variants are for handling successful resolution, the !
variants are
for handling errors. The T
variants of each return the lhs instead of the
rhs, which is useful for pipeline steps that are used for side effects
(printing, plotting, saving).
promise %...>% func()
is equivalent to promise %>% then(func)
.
promise %...!% func()
is equivalent to promise %>% catch(func)
.
promise %...T>% func()
is equivalent to promise %T>% then(func)
.
promise %...T!% func()
is equivalent to promise %T>%
catch(func)
or promise %>% catch(func, tee = TRUE)
.
One situation where 3. and 4. above break down is when func()
throws an
error, or returns a promise that ultimately fails. In that case, the failure
will be propagated by our pipe operators but not by the
magrittr-plus-function "equivalents".
For simplicity of implementation, we do not support the magrittr feature of
using a .
at the head of a pipeline to turn the entire pipeline into a
function instead of an expression.