ElixirDrops

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Capture warnings with Code.with_diagnostics/2

Use Code.with_diagnostics/2 when warnings and errors need to become structured data instead of terminal text....

almirsarajcic

5 hours ago

Update matching list items with Access.filter/1

Use Access.filter/1 to update only the list elements that match a predicate, without mapping and rebuilding the surrounding structure yourself....

almirsarajcic

yesterday

Discard late replies with process aliases

Send hand-rolled request replies to a process alias, then deactivate the alias when the caller stops waiting....

almirsarajcic

2 days ago

Reject unknown struct keys with struct!/2

Use struct!/2 when runtime attributes must contain only fields that belong to the struct....

almirsarajcic

3 days ago

The Module Behind the Curtain

Use defdelegate when a function should simply forward its arguments to another module....

spapiernik

3 days ago

Build strings with iodata, not concatenation

Building a string by repeatedly <>-ing onto an accumulator can be quadratic — but not for the reason most people think. The BEAM has a runtime optimiz...

almirsarajcic

4 days ago

Ecto's :utc_datetime silently drops microseconds

:utc_datetime stores second precision. Hand it a DateTime.utc_now/0 value — which carries microseconds — and Ecto.Type.cast/2 truncates it with no war...

almirsarajcic

5 days ago

get_in/2 needs Access.key!/1 for structs

get_in/2, put_in/3, and update_in/3 walk a path of atom keys through maps and keyword lists just fine — but the same atom path raises on a struct. ``...

almirsarajcic

6 days ago

Decimal `==` is not value equality

Decimal.new("1.0") and Decimal.new("1.00") represent the same number, but Elixir's == says they are different:...

almirsarajcic

6 days ago

`dbg/2` shows every step of your pipeline

Debugging a pipeline usually means breaking it apart with IO.inspect/2 calls between every stage, labelling each one so you can tell them apart, then ...

almirsarajcic

8 days ago

Stop blocking your supervisor in `init/1`

Every millisecond spent in init/1 is a millisecond your entire supervision tree is frozen. start_link/1 does not return until init/1 does, and the sup...

almirsarajcic

12 days ago

Name dynamic processes with `:via` tuples

The moment you need one process per game, per room, or per upload, the naming problem shows up — and the tempting fix is String.to_atom("game_#{id}")....

almirsarajcic

13 days ago

`attr` turns component bugs into compile errors

A function component is just a function taking assigns, which means a typo'd or forgotten assign fails the way any missing map key fails: at render ti...

almirsarajcic

14 days ago

`Ecto.Enum` maps atoms to integer columns

Status columns tend to rot the same way everywhere: an integer in the database, a string in the params, an atom in the business logic, and String.to_a...

almirsarajcic

14 days ago

Sub-binaries keep the whole payload in memory

Slicing a binary in Elixir does not copy it. binary_part/3 on a 1 MB payload hands you 100 bytes that quietly reference all 1 MB — and the parent cann...

almirsarajcic

15 days ago