Chained pattern match

[mudasobwa]

Consider the following code:

%{a_left: a_left} = a_full = %{} = a_full = %{a_right: a_right} = %{a_left: 42, a_right: 42}
#⇒ %{a_left: 42, a_right: 42}

Is every element in the chain is always matched against the rightmost one? Is there any reference/link/documentation all around describing this behavior? The official doc is pretty concise

[LostKobrakai]

elixir-lang/elixir/blob/master/lib/elixir/pages/Operators.md#operator-precedence-and-associativity

This shows right to left as precedance, so do put everything on the left onto parenthesis starting from the right and you‘ll explicitly see the order of application. Also the pattern match expression will always evaluate to the full matched value. So yes everything will match the rightmost value.

[mudasobwa]

@LostKobrakai

the pattern match expression will always evaluate to the full matched value

Indeed. I somehow missed that.

[peerreynders]

FYI:

Reference material on pattern matching precedence order?

Yes, this is how it works. It means that each pattern will be matched against the term. There is an implicit grouping (Pattern0 = (Pattern2 = … (PatternN = Term)…)) so if variables occur in many the binding behaves as the matching goes from the inside out. Fro example: iex(1)> {a,b} = {b,a} = {3,4} {3, 4} iex(2)> a 3 iex(3)> b 4 iex(4)> {b,a} = {a,b} = {3,4} {3, 4} iex(5)> a 4 iex(6)> b 3 If you pin (’^’ ) a variable in any of the patterns then this importing of the value occurs before any mat…