pattern.nanopass.pass — com.github.pangloss/pattern 1.0.435

-add-env-args clj

(-add-env-args rule-list env-args)

combine-rules clj

(combine-rules dialects form-rules)

Combine a collection of rule combinators which each handle inputs tagged with a specific type and create an [[on-mutual]] rule for them.

form-rules is map of group-type to rule-fn, or may be a flat list of pairs in the typical Clojure style.

Each group-type is one of the arrow expressions => ==> ===>. For example (=> FromForm ToForm). Arrow length is used to decide which forms are used for the entry expression. If any long ===> arrows are present, they will be tried unconditionally of expression type. If they do not match, or if there are no long arrows, then if any medium ==> arrows are present, they will be tried, but respecting their input type. If any long or medium arrows are present, short => arrows are not tried. If there are only short arrows, then they are all treated like medium arrows.

defpass clj macro

(defpass name dialects compiled & fn-tail)

Define a pass with the given name and dialects. Use (=> FromDialect ToDialect) to specify the dialect pair.

This may be used either as a simple pass definition with no function body defined, in which case it will define name to be the value of the compiled argument, which may be a rule, let-rulefn, or any other expression.

Alternately, if a fn-tail is defined then the compiled expression must contain <> exactly once in the location you want the function definition to be inserted. The point of this exercise is to allow the rule functions to be precompiled while still allowing a clear syntax for defining a pass.

Example usage:

  (defpass naive-cps (=> LambdaCalc CPS)
    (let-rulefn [(M (=> Expr MExpr)
                    [(rule '(fn [?var] ?expr)
                            (let [k (gensym 'k)]
                              (sub (fn [?var ?k] ~(T expr k)))))
                     (rule '(? s symbol?) s)])
                 (T* (=> Expr TExpr) [cont]
                    [(rule '(?:as expr (fn ??_))
                            `(~cont ~(M expr)))
                     (rule '(? s symbol?)
                           `(~cont ~(M s)))
                     (rule '(?f ?e)
                            (let [fs (gensym 'f)
                                  es (gensym 'e)]
                              (T f (sub (fn [?fs]
                                          ~(T e (sub (fn [?es]
                                                       (?fs ?es ?cont)))))))))])
                 (fn T [expr cont]
                    (first (T* expr {:cont cont})))]
      <>)
    [expr cont]
    (T expr cont))

  (naive-cps '(g a) ''halt)
  ;; => ((fn [f48299] ((fn [e48300] (f48299 e48300 (quote halt))) a)) g)

In the above example, M is a simple rule, but T* uses its env to get the value of cont. The [cont] clause in the T* definition causes the rule handler to be wrapped in (let [cont (:cont %env)] ...).

At the end of the definition, the [expr cont] (T expr cont) expression gets wrapped with (defn naive-cps ...), and the defn is placed at the point indicated by <>.

LambdaCalc and CPS are the dialects being transformed between. Expr is a form in LambdaCalc and MExpr and TExpr are forms in CPS.

dialectify clj

(dialectify dialects expr)

Used by defpass to rewrite let-rulefn to use its dialects

get-form clj

(get-form dialect form-name)

insert-defn clj

(insert-defn compiled name fn-tail)

Used by defpass to replace <> with the pass entry function

let-rulefn clj macro

(let-rulefn rulefns & body)

This does a simple transformation to allow all of the rules in rule-fns to refer to each other. Each rule list is made [[directed]], and all of the rule lists are assembled into an [[on-mutual]] set of rules via combine-rules. The combined ruleset is bound to %pass.

If no body expressions are provided, this will return %pass, otherwise it will return the value of the last expression in the body.

When used inside defpass, this call is rewritten to use let-rulefn* with the dialect pair specified in the pass. If you don't want this behaviour, use let-rulefn* directly with nil for the dialects argument.

let-rulefn* clj macro

(let-rulefn* dialects rulefns & body)

rulefn* clj