Add helper for nullable decoders

Author: Resonious

gleam.toml

@@ -1,5 +1,5 @@
 name = "pturso"
-version = "1.0.0"
+version = "1.1.0"
 description = "Turso for Gleam. Similar to the sqlight library, but uses a Port instead of a NIF (so it works fine even for statically linked BEAM builds)."
 licences = ["MIT"]
 repository = { type = "github", user = "Resonious", repo = "pturso" }

src/pturso.gleam

@@ -1,3 +1,4 @@
+import gleam/option
 import gleam/list
 import gleam/result.{try}
 import gleam/dynamic/decode
@@ -34,6 +35,11 @@ pub type Error {
   DecodeError(errors: List(decode.DecodeError))
 }
 
+pub fn nullable(decoder: decode.Decoder(Param)) -> decode.Decoder(Param) {
+  decode.optional(decoder)
+  |> decode.map(option.unwrap(_, Null))
+}
+
 @external(erlang, "pturso_ffi", "now_ms")
 fn now_ms() -> Int