Collections

Source

github.com/denful/bend

eachValue lens

Apply lens to every value in an attrset.

(bend.eachValue bend.int).get { x = 1; y = 2; z = 3; }
# right { x = 1; y = 2; z = 3; }

(bend.eachValue bend.int).get { x = 1; y = "bad"; z = 3; }
# left "bad"

mapKey f

Rename attrset keys with function f.

(bend.mapKey (k: k + "_ok")).get { a = 1; b = 2; }
# right { a_ok = 1; b_ok = 2; }

sequence [lens ...]

Gather results of multiple lenses on the same source into a list.

let lens = bend.sequence [ (bend.attr "x") (bend.attr "y") (bend.attr "z") ];
in lens.get { x = 1; y = 2; z = 3; }
# right [ 1 2 3 ]

zip lensA lensB

Focus two parts of the same source into { a; b; }.

(bend.zip (bend.attr "x") (bend.attr "y")).get { x = 1; y = 2; }
# right { a = 1; b = 2; }

(bend.zip (bend.attr "x") (bend.attr "y")).set { x = 0; y = 0; z = 3; } { a = 10; b = 20; }
# right { x = 10; y = 20; z = 3; }