Update 2025-08-17-custom-error-types.md

Co-authored-by: Seth Tisue <[email protected]>

Author: djspiewak

collections/_posts/2025-08-17-custom-error-types.md

@@ -10,7 +10,7 @@ meta:
 
 One of the most famous and longstanding limitations of the Cats Effect `IO` type (and the Cats generic typeclasses) is the fact that the only available error channel is `Throwable`. This stands in contrast to bifunctor or polyfunctor techniques, which add a typed error channel within the monad itself. You can see this easily in type signatures: `IO[String]` indicates an `IO` which returns a `String` or may produce a `Throwable` error. Something like `BIO[ParseError, String]` would represent a `BIO` that produces a `String` *or* raises a `ParseError`. The latter type signature is more general than `Throwable`, since it allows for user-specified error types, and it's somewhat more explicit about where errors can and cannot occur.
 
-In a meaningful sense, type type of bifunctor error encoding is analogous to *checked* exceptions in Java, whereas monofunctor error encoding (like Cats Effect's `IO`) is analogous to *unchecked* exceptions. Both are valid design decisions for an effect type, but they come with different benefits and tradeoffs.
+In a meaningful sense, this type of bifunctor error encoding is analogous to *checked* exceptions in Java, whereas monofunctor error encoding (like Cats Effect's `IO`) is analogous to *unchecked* exceptions. Both are valid design decisions for an effect type, but they come with different benefits and tradeoffs.
 
 Cats has long been quite prescriptive about monofunctor effects, in part because this considerably simplifies the compositional integration space. Libraries like Fs2, Http4s, Calico, and so many more are able to build on top of parametric effects (the famous `F[_]`) with a consistent understanding of what error channels are available and how they're going to behave. This has *very* subtle interactions with concurrent logic and resource handling, and by insisting on a monofunctor calculus, the Cats ecosystem is able to maintain very strong properties with relatively simple implementations in these areas.