pit v0.1.3 Pit

Summary

Macros

The pit macro lets you pipe value transformations by pattern matching on data as it is passed down the pipe

Functions

pit_pipe(piped, expr, options)

Macros

pit(pipe, expr, options \\ [])

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).

Examples

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, :not_found}
...> response
...>    |> pit(! {:error, _})
...>    |> pit(n <- {:ok, n})
** (Pit.PipedValueMismatch) did not expect piped value to match `{:error, _}` but got `{:error, :not_found}`


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` but got `{:ok, 22}`


iex> # You can provide a default value in case of mismatch
iex> import Pit
...> response = {:error, :not_found}
...> response
...>    |> pit({:ok, _}, else_value: {:ok, :default})
...>    |> pit(n <- {:ok, n})
:default


iex> # Or you can pipe the mismatch value to other pipe
iex> # and get its value down a more interesting transformation flow.
iex> import Pit
...> response = {:ok, "hello"}
...> response
...>   |> pit({:ok, n} when is_integer(n),
...>        else: pit(s <- {:ok, s} when is_binary(s)) |> String.length |> pit({:ok, len} <- len))
...>   |> pit(x * 2 <- {:ok, x})
10