Add collect and collect-one.

This commit is contained in:
Christopher O'Donnell 2016-06-11 00:55:58 -04:00
parent 1c5861f44f
commit 431dd3ea82

View file

@ -159,3 +159,49 @@ nil
(0 1 2 3 4)
```
## the lower case ones
### bind-params*
Binds late binding params. Write this one later.
### codewalker
Walks code? Let's do this one later.
### collect
`(collect & paths)`
`collect` adds the result of running `collect` with the given path on the current value to the collected vals. Note that `collect`, like `select`, returns a vector containing its results. If `transform` is called, each collected value will be passed in as an argument to the transforming function, with the resulting value as the last argument.
```clojure
=> (select-one [(collect ALL) FIRST] (range 3))
[[0 1 2] 0]
=> (select [(collect ALL) ALL] (range 3))
[[[0 1 2] 0] [[0 1 2] 1] [[0 1 2] 2]]
=> (select [(collect ALL) (collect ALL) ALL] (range 3))
[[[0 1 2] [0 1 2] 0] [[0 1 2] [0 1 2] 1] [[0 1 2] [0 1 2] 2]]
;; Add the sum of the evens to the first element of the seq
=> (transform [(collect ALL even?) FIRST] (fn [evens first] (reduce + first evens)) (range 5))
(6 1 2 3 4)
;; Replace the first element of the seq with the entire seq
=> (transform [(collect ALL) FIRST] (fn [all _] all) (range 3))
([0 1 2] 1 2)
```
### collect-one
`(collect-one & paths)`
`collect-one` adds the result of running `collect` with the given path on the current value to the collected vals. Note that `collect-one`, like `select-one`, returns a single result. If there is more than one result, an exception will be thrown. If `transform` is called, each collected value will be passed in as an argument to the transforming function, with the resulting value as the last argument.
```clojure
=> (select-one [(collect-one FIRST) LAST] (range 5))
[0 4]
=> (select [(collect-one FIRST) ALL] (range 3))
[[0 0] [0 1] [0 2]]
=> (transform [(collect-one :b) :a] + {:a 2 :b 3})
{:a 5 :b 3}
=> (transform [(collect-one :b) (collect-one :c) :a] * {:a 3 :b 5 :c 7})
{:a 105 :b 5 :c 7}