if R.cond resolve an not undefined value, should execute a pipe function and pass the value to the pipe function...
const publishClient = (resp, cb) => {
console.log('Publishing ', resp);
cb()
}
// Applying same process
const format = (letter) => ({'letter': letter});
const concact = R.curry((num, letter) => num + '=' + letter);
// my method publish
const publish = partialRight(publishClient, [function() { console.log('Callback called!') }]);
// conditions to check
const condToRes = R.cond([
[equals(1), concact('A')],
[equals(2), concact('B')],
[equals(3), concact('C')],
[equals(4), concact('D')],
[equals(5), concact('E')],
]);
// Publish only if condition resolves
// const resolveCond = when(condToRes, pipe(format, publish)) // NOT WORK,concact FN is ignored!
const resolveCond = pipe( // TRYING
condToRes,
when(HOW TO CHECK condToRes IS NOT NIL, pipe(format, publish))
);
// Call
resolveCond(1)
// SHOULD DISPLAY ..
Publishing
{"letter":"A=1"}
Callback called!
To test whether a value is null or undefined you can make use of R.isNil. When combined with the R.complement combinator, this will produce a function that evaluates to true when applied to a value that is not null/undefined.
This can be used to update your example to:
const resolveCond = pipe(
condToRes,
when(complement(isNil), pipe(format, publish))
);
Alternatively, R.unless can be used instead of R.when, which removes the need to wrap R.isNil with R.complement.
const resolveCond = pipe(
condToRes,
unless(isNil, pipe(format, publish))
);
Both approaches are equivalent, though R.unless perhaps reads a little better.
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