maps_in

An Erlang library to handle nested maps.

Table of contents

• General info
• Usage
  • filter/3
  • filtermap/3
  • find/3
  • fold/4
  • foreach/3
  • get/2
  • get/3
  • keys/2
  • is_key/3
  • iterator/2
  • map/3
  • merge/3
  • merge_with/4
  • put/3
  • remove/3
  • size/2
  • take/3
  • to_list/2
  • update/3
  • update_with/3
  • update_with/4
  • values/2
  • with/3
  • without/3
• Build
• Test

General info

Erlang does not provide functions to handle nested maps, so this lib has this purpose and always uses a list of keys to manipulate maps.

Usage

filter/3

1> Map = #{erlang => #{example => #{a => 2, b => 3, c => 4, "a" => 1, "b" => 2, "c" => 4}}}.
#{erlang =>
      #{example =>
            #{a => 2,b => 3,c => 4,"a" => 1,"b" => 2,"c" => 4}}}
2> Pred = fun(K, V) -> is_atom(K) andalso (V rem 2) =:= 0 end.
#Fun<erl_eval.41.3316493>
3> maps_in:filter([erlang, example], Pred, Map).
#{erlang => #{example => #{a => 2,c => 4}}}

filtermap/3 (OTP 24.0)

<!-- TODO -->

find/3

<!-- TODO -->

fold/4

<!-- TODO -->

foreach/3

<!-- TODO -->

get/2

1> Map = #{my => #{nested => map}}.
#{my => #{nested => map}}
2> maps_in:get([my, nested], Map).
map

get/3

1> Map = #{my => #{nested => map}}.
#{my => #{nested => map}}
2> maps_in:get([my, unknown_key], Map, default).
default

keys/2

<!-- TODO -->

is_key/3

<!-- TODO -->

iterator/2 (OTP 21)

<!-- TODO -->

map/3

<!-- TODO -->

merge/3

<!-- TODO -->

merge_with/4 (OTP 24.0)

<!-- TODO -->

put/3

1> Map = #{my => #{more => #{deep => #{}}}}.
#{my => #{more => #{deep => #{}}}}
2> maps_in:put([my, more, deep], #{nested => map}, Map).
#{my => #{more => #{deep => #{nested => map}}}}

remove/3

<!-- TODO -->

size/2

<!-- TODO -->

take/3

<!-- TODO -->

to_list/2

<!-- TODO -->

update/3

1> Map = #{my => #{more => #{deep => #{}}}}.
#{my => #{more => #{deep => #{}}}}
2> maps_in:update([my, unknown_key], error, Map).
** exception error: bad key: unknown_key
3> maps_in:update([my, more, deep], #{nested => map}, Map).
#{my => #{more => #{deep => #{nested => map}}}}

update_with/3

1> Map = #{someone => #{age => 17}}.
#{someone => #{age => 17}}
2> maps_in:update_with([someone, age], fun(Age) -> Age + 1 end, Map).
#{someone => #{age => 18}}

update_with/4

<!-- TODO -->

values/2

<!-- TODO -->

with/3

<!-- TODO -->

without/3

<!-- TODO -->

Build

$ rebar3 compile

Test

$ rebar3 eunit