pattern.r3.rewrite — com.github.pangloss/pattern 1.0.435

This namespace defines several rulesets and related macros that enhance the expressive power of the rules engine.

Most of these rulesets are defined in a style inspired by the nanopass compiler, using directed to control the rule matcher's descent into the expression being transformed.

The rules defined in this namespace must make use of a limited subset of this library's functionality since they are defining that functionality in terms of the base operations.

Arity-1 rules may not be used, nor may sub or quo.

This namespace defines several functions in terms of various combinations of the same rulesets. The core idea is to transform native Clojure sytax-quoted forms. In the case of regular quoted lists, they may be expanded into syntax-quoted form before being transformed and then possibly simplified back as close to their original shape as possible. This transformation enables unquoting on regular quoted lists and other data structures.

Note that sequence is included in the rules because when booting, Clojure's syntax quote expands slightly differently than at runtime. It also uses lists rather than Cons objects at boot.

*on-marked-insertion* clj

add-env-args* clj

The rewrite used by a macro that recursively adds metadata to rules before the rule macro runs. It uses the metadata to let-bind values from %env within rule-handlers.

array-or-hash-map clj

(array-or-hash-map & items)

cleanup-rule-pattern clj

Makes syntax-quoted rule patterns presentable

do-unquote* clj

eval-spliced clj

(eval-spliced x)

Experimental. Uses spliced to transform regular lists, then uses eval to resolve spliced data. Doesn't resolve any data in the local scope.

evaluate-structure clj

Evaluate syntax quoted forms

expand-and clj

(expand-and types results)

expand-or clj

(expand-or types results)

expand-pattern clj

pure-pattern clj

qsub* clj

qsub+ clj

Same as qsub* but keeps symbol namespaces

quo clj macro

(quo expr)

Remove symbol namespaces.

Useful for cleaning up namespaces in syntax-quoted input data. Otherwise, use sub.

Requires that the expression is syntax quoted. Does not perform any other transformation.

Usage:

(quo `(expt x ~(+ 1 1)))

remove-expressions clj

Replace all unquoted expressions with 'identity but leave the structure of the expression unmodified.

remove-matcher-ns clj

This makes (some.ns/? some.ns/x) look like (? x), etc when displaying rules.

remove-symbol-namespaces clj

rmeta clj macro

(rmeta)

Expands to (meta (:rule/datom %env))

rule-src clj

Makes syntax-quoted rules presentable

scheme-style clj

simplify-expr clj

simplify-more clj

splice* clj

spliced clj

(spliced form)

A function that allows regular quoted lists to be spliced just like syntax-quoted ones, but only really works within macros because the spliced in data needs to be evaluated and it doesn't seem possible to do that at runtime except with [[eval]], which does not use the current evaluation scope. If that works for you, use eval-spliced, but usually you will be better off with either the sub (recommended), or quo macros.

This may eventually be useful together with SCI?

sub clj macro

(sub form)

(sub f form)

Statically macroexpand substitution patterns expressed exactly like matcher patterns.

This produces what I expect shoud be optimally fast substitutions, but differs from pattern.substitute/substitute in that it requires that all substitution patterns must be bound, and will produce a compilation error if not.

The arity 2 version allows substitutions to be transformed by the supplied function before being inserted if they are marked with <- or wrapped with (?:<- ...)

sub+ clj macro

(sub+ & etc)

Same as sub. Here for backward compatibility

sub- clj macro

(sub- form)

(sub- f form)

Just like sub but strips all namespaces from symbols.

subm clj macro

(subm form)

(subm form metadata)

Perform substitution and attach the provided metadata.

If called arity-1, copy the rule's original matching form's metadata onto the resulting form, using rmeta to capture the metadata.

subm+ clj macro

(subm+ form)

(subm+ form metadata)

Like subm but checks that form is an IObj before attaching metadata.

Useful for generated expressions.

to-syntax-quote* clj

unquote-all* clj

unwrap-list clj

unwrap-quote clj

with-env-args clj macro

(with-env-args bindings rules)

Attach :env-args metadata to rules to enable convenient binding of env data in the rule handlers.