pit v0.1.1 Pit
The pit
macro lets you pipe value transformations by pattern matching
on data as it is passed down the pipe.
The syntax for transforming values is expression |> pit(value <- pattern)
.
iex> # The following will ensure there are no errors on iex> # the response and double the count value from data. iex> import Pit …> response = {:ok, %{data: %{“count” => 10}, errors: []}} …> response …> |> pit(data <- {:ok, %{errors: [], data: data}}) …> |> pit(count * 2 <- %{“count” => count}) 20
iex> # By using the ! operator, you can pipe values iex> # only if they dont match some pattern iex> # This example only pipes anything that aint an error iex> import Pit …> response = {:cool, 22} …> response …> |> pit(! {:error, }) …> |> pit(n <- {, n}) 22
iex> # if the piped value does not match an error is raised.
iex> import Pit
…> response = {:error, :notfound}
…> response
…> |> pit(! {:error, })
…> |> pit(n <- {:ok, n})
** (Pit.PipedValueMismatch) expected piped value not to match {:error, _}
iex> # also, when a guard fails an error is raised
iex> import Pit
…> response = {:ok, 22}
…> response
…> |> pit({:ok, n} when n > 30)
…> |> pit(n <- {:ok, n})
** (Pit.PipedValueMismatch) expected piped value to match {:ok, n} when n > 30
iex> # You can provide a fallback value for mismatch iex> import Pit …> response = {:error, :notfound} …> response …> |> pit({:ok, }, else: {:ok, :default}) …> |> pit(n <- {:ok, n}) :default