dance.core — dance 0.1.3

*default-dance* clj

adapt-dance-fns clj

(adapt-dance-fns dance)

add-to-right-context clj

(add-to-right-context ctx & kvs)

atomic-dance? clj

(atomic-dance? dance)

atomic-dances clj

(atomic-dances dance)

backtrack clj

(backtrack form)

(backtrack form ctx)

backtrack? clj

(backtrack? ctx)

backtracking-dance clj

break-dance! clj

(break-dance! form)

(break-dance! form ctx)

Used to immediately return a value during a dance. Can be used in any of the dance fns.

context-walk clj

(context-walk step inner outer form context)

ctx->| clj

ctx-comp clj

dance clj

(dance form & args)

A finely tunable, composable, equivalent of clojure.walk with enhancements.

For a demo, just run

(dance
  '(+ 1 (- 2 (* 3 (/ 4 5) (dec 3))))
  :walk?          #(and (seq? %) (-> % first (not= 'dec)))
  :pre?           #(and (seq? %) (-> % first (not= '/)))
  :pre            vec
  :post?          number?
  :post           (fn [x ctx] [(inc x) (update ctx :cnt inc)])
  :context        {:cnt 0}
  :return         :form-and-context
  :debug          true
  )

Dance fns

See https://en.wikipedia.org/wiki/Tree_traversal

Namely walk?, pre?, pre, post?, post, before, after, before-all and after-all.

pre? and post? respectively condition pre and post while the walk of the substructure itself occurs in between and is conditioned by walk?. beforeand after are respectively called before and after any node is processed (before pre) while before-all and after-all are called once, at the beginning and the end of the walk.

Traversal appears to occur in pre-order for before, walk? pre? and pre, but in post-order for post?, post and after.

Note that nodes that will not be walked may still be processed by pre and post.

Context

Dance fns can have 1 argument (the node at hand) or 2, in order to receive an optional, latent context. If so, they must return a vector like [result context] where result can be a processed substructure (pre, post, ...) or the return value of a predicate (pre?, post?, ...).

This context is passed walking down the structure from node to subnodes then back to the parent nodes up to the initial root in a depth-first manner.

By default, it is global to the walk and is not scoped by the depth at which it being accessed. In other words, the context is passed from siblings to siblings in the order of the walk and modifications done to it when walking a node can be seen when walking the sister nodes, their children and eventually their ancestors.

However the :scoped option can be used to specify which keys in the context should be scoped to the current node and its children and not thread through the whole traversal. More specifically parents pass the context to their children and changes made by the children are not visibile by their ancestors or siblings.

Note that variadic arguments functions count as single-argument to accomodate for functions like constantly, and thus cannot receive a context.

Merging dances

Multiple dances can be passed to dance, including a varargs dance:

(dance collection
  first-dance
  second-dance
  :before third-dance-before
  :after  third-dance-after)

Options in these dance will be merged in a smart way according to this plan:

- before, pre : composed from left to right
- after, post : composed from right to left
- pre?, walk? : composed like `and`, from left to right
- post?       : composed like `and`, but from right to left.
- context     : composed with `merge`
- scoped      : composed with `#(clojure.set/union (set %1) (set %2))`

:debug, :return, and :step are merged normally, i.e. via right-most preference.

Early return

At any moment, from within any of the dance fns, break-dance! can be used to halt the execution, returning the given form (and optional context). Consider:

(dance [1 2 3 4 5 6]
  :pre? number?
  :pre (fn [x]
          (if (> x 4)
            (break-dance! :abc)
            (println x))))
=> :abc

Additional options

• context : The initial context (defaults to {})
• return : :form, :form-and-context or :context (:form).
• step : low-level option. See step and step-indexed. Defaults to step
• depth : The intial depth. Determines tabulation (0) when debugging.
• debug : To print a detailed trace of the walk (false).
• debug-depth : To limit the debug trace to a certain depth.
• debug-context-blacklist: To mask certain context keys when debugging.
• debug-context-whitelist: To display only certain context keys.

Any option passed to dance is optional, including the dance fns.

dance-impl clj

(dance-impl dance)

dance-name clj

(dance-name dance)

def-collecting-dance clj macro

(def-collecting-dance nme & args)

defdance clj macro

(defdance nme & args)

dependent-dances clj

(dependent-dances dance)

depth-dance clj

A dance that keeps track of the depth of the traversal. Context key: :depth.

depth-dance* clj

See depth-dance.

empty-dance clj

free-symbols-collecting-dance clj

free-symbols-collecting-dance* clj

See free-symbols-collecting-dance.

free-symbols-tracking-dance clj

Accepts an optional :bound-sym? function in the context.

free-symbols-tracking-dance* clj

See free-symbols-tracking-dance.

get-right-context clj

(get-right-context ctx)

indexed-dance clj

A dance that keeps track of the index the current nodes resides at in its parent node. The index can be either a number for list/vectors or anything else for maps. Context key: :index.

indexed-dance* clj

See indexed-dance.

leafs-collecting-dance clj

leafs-collecting-dance* clj

See leafs-collecting-dance.

locals-tracking-dance clj

locals-tracking-dance--fn*-multiple-bodies* clj

See [[locals-tracking-dance--fn*-multiple-bodies]].

locals-tracking-dance--fn*-single-body* clj

See [[locals-tracking-dance--fn*-single-body]].

locals-tracking-dance--handle-locals-from-left* clj

See [[locals-tracking-dance--handle-locals-from-left]].

locals-tracking-dance--let*-loop*-letfn*-binding-sym-expr* clj

See [[locals-tracking-dance--let*-loop*-letfn*-binding-sym-expr]].

locals-tracking-dance--let*-loop*-letfn*-binding-vec* clj

See [[locals-tracking-dance--let*-loop*-letfn*-binding-vec]].

locals-tracking-dance--top-level* clj

See [[locals-tracking-dance--top-level]].

map-entry clj

(map-entry x)

merge-dances clj

(merge-dances & dances)

Merges multiples dances together. A dance is a hash of arguments to dance.

not-processing-quoted-forms-dance clj

not-processing-quoted-forms-dance* clj

See not-processing-quoted-forms-dance.

original-form-dance clj

original-form-dance* clj

See original-form-dance.

parent-dance clj

A dance that keeps track of the parent node. Context keys: :parent (:next-parent).

parent-dance* clj

See parent-dance.

parents-dance clj

A dance that keeps track of the parent nodes, in genealogic order (parent, grand-parent, ...). Context keys: :parents (:next-parent).

parents-dance* clj

See parents-dance.

path-dance clj

A dance that keeps track of the path from the root of the datastructure to the current node. To use a path to find back the node it leads to, use shuriken.core/get-nth-in and sister functions since contrary to get-in, assoc, etc ..., they support traversing sequences. Context key: :path.

path-dance* clj

See path-dance.

reluctant-macroexpanding-dance clj

reluctant-macroexpanding-dance* clj

See reluctant-macroexpanding-dance.

right-context-dance clj

right-context-dance* clj

See right-context-dance.

splice clj

(splice form)

splicing-dance clj

splicing-dance* clj

See splicing-dance.

step clj

(step form {:keys [initial-acc initial-context wrap inner outer]})

step-indexed clj

(step-indexed form {:keys [initial-acc initial-context wrap inner outer]})

subdances clj

(subdances dance)

update-right-context clj

(update-right-context ctx k f & args)

with-context clj

(with-context ctx)

(with-context form ctx)

with-context-dance clj

with-context? clj

(with-context? form)

with-dance-impl clj macro

(with-dance-impl impl dance)

with-dance-name clj macro

(with-dance-name dance-name dance)

with-dependent-dances clj macro

(with-dependent-dances dependent-dances dance)