emmy.expression.cse
This namespace implements subexpression extraction and "elimination", the process we use to avoid redundant computation inside of a simplified function body.
This namespace implements subexpression extraction and "elimination", the process we use to avoid redundant computation inside of a simplified function body.
extract-common-subexpressionsclj/s
(extract-common-subexpressions expr continue)(extract-common-subexpressions expr
continue
{:keys [gensym-fn deterministic?]
:or {gensym-fn
(a/monotonic-symbol-generator 8 "_")}})Considers an S-expression from the point of view of optimizing its evaluation by isolating common subexpressions into auxiliary variables.
Accepts:
- A symbolic expression
expr - a continuation fn
continueof two arguments:- a new equivalent expression with possibly some subexpressions replaced by new variables (delivered by the supplied generator, see below)
- a seq of pairs of
[aux variable, subexpression]used to reconstitute the value.
Calls the continuation at completion and returns the continuation's value.
Optional Arguments
:gensym-fn: side-effecting function that returns a new, unique
variable name prefixed by its argument on each invocation.
monotonic-symbol-generator by default.
NOTE that the symbols should appear in sorted order! Otherwise we can't
guarantee that the binding sequence passed to continue won't contain entries
that reference previous entries.
:deterministic?: if true, the function will assign aux variables by sorting
the string representations of each term before assignment. Otherwise, the
nondeterministic order of hash maps inside this function won't guarantee a
consistent variable naming convention in the returned function. For tests, set
:deterministic? true.
Considers an S-expression from the point of view of optimizing its evaluation
by isolating common subexpressions into auxiliary variables.
Accepts:
- A symbolic expression `expr`
- a continuation fn `continue` of two arguments:
- a new equivalent expression with possibly some subexpressions replaced by
new variables (delivered by the supplied generator, see below)
- a seq of pairs of `[aux variable, subexpression]` used to reconstitute the
value.
Calls the continuation at completion and returns the continuation's value.
### Optional Arguments
`:gensym-fn`: side-effecting function that returns a new, unique
variable name prefixed by its argument on each invocation.
`monotonic-symbol-generator` by default.
NOTE that the symbols should appear in sorted order! Otherwise we can't
guarantee that the binding sequence passed to `continue` won't contain entries
that reference previous entries.
`:deterministic?`: if true, the function will assign aux variables by sorting
the string representations of each term before assignment. Otherwise, the
nondeterministic order of hash maps inside this function won't guarantee a
consistent variable naming convention in the returned function. For tests, set
`:deterministic? true`.cljdoc is a website building & hosting documentation for Clojure/Script libraries
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