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compile.scm
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2283 lines (1948 loc) · 66.7 KB
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; Stak Scheme compiler.
;
; All compiler-internal variables contain at least one `$` or `%` character in their names.
(import
(scheme base)
(only (scheme cxr))
(only (scheme lazy))
(scheme eval)
(only (scheme file))
(only (scheme inexact))
(scheme process-context)
(scheme read)
(only (scheme write)))
(define frontend
'(
; Instructions
(define constant-instruction 0)
(define get-instruction 1)
(define set-instruction 2)
(define if-instruction 3)
(define call-instruction 4)
(define nop-instruction 65535)
; Primitives
(define primitives
'(($$rib 0)
($$close 1)
($$unbind 2)
($$< 10)
($$+ 11)
($$- 12)
($$* 13)
($$/ 14)))
; Types
(define pair-type 0)
(define null-type 1)
(define boolean-type 2)
(define procedure-type 3)
(define symbol-type 4)
(define string-type 5)
(define char-type 6)
(define vector-type 7)
(define bytevector-type 8)
; Utility
(define (debug . xs)
(write xs (current-error-port))
(newline (current-error-port)))
(define (code-rib tag car cdr)
(rib car cdr tag))
(define (call-rib arity procedure continuation)
(code-rib (+ call-instruction arity) procedure continuation))
(define (constant-rib constant continuation)
(code-rib constant-instruction constant continuation))
(define (nop-rib continuation)
(code-rib nop-instruction 0 continuation))
(define (data-rib type car cdr)
(rib car cdr type))
(define (make-procedure arity code environment)
(data-rib procedure-type (cons-rib arity code) environment))
; Because we have the `bytevector->list` procedure in Stak Scheme's standard library and
; the `bytevector-u8-ref` procedure in the standard library uses `bytevector->list` internally and
; Stak Scheme allows overwriting imported symbols,
; we intentionally name this procedure differently from `bytevector->list`.
(define (bytes->list xs)
(let loop ((index 0))
(if (< index (bytevector-length xs))
(cons (bytevector-u8-ref xs index) (loop (+ 1 index)))
'())))
(define (last-cdr xs)
(if (pair? xs)
(last-cdr (cdr xs))
xs))
(define (set-last-cdr! xs x)
(if (pair? (cdr xs))
(set-last-cdr! (cdr xs) x)
(set-cdr! xs x)))
(define (filter f xs)
(if (null? xs)
'()
(let ((x (car xs))
(xs (filter f (cdr xs))))
(if (f x)
(cons x xs)
xs))))
(define (list-head xs n)
(if (zero? n)
'()
(cons
(car xs)
(list-head (cdr xs) (- n 1)))))
(define (list-index f xs)
(let loop ((xs xs) (index 0))
(cond
((null? xs)
#f)
((f (car xs))
index)
(else
(loop (cdr xs) (+ index 1))))))
(define (equal-index f)
(lambda (x xs)
(list-index (lambda (y) (f x y)) xs)))
(define memv-index (equal-index eqv?))
(define memq-index (equal-index eq?))
(define (append-map f . xs)
(apply append (apply map f xs)))
(define (relaxed-length xs)
(do ((xs xs (cdr xs)) (y 0 (+ y 1)))
((not (pair? xs))
y)))
(define (relaxed-map f xs)
(if (pair? xs)
(let ((x (f (car xs))))
(cons x (relaxed-map f (cdr xs))))
(f xs)))
(define (deep-map f x)
(let ((x (f x)))
(if (list? x)
(map (lambda (x) (deep-map f x)) x)
x)))
(define (relaxed-deep-map f xs)
(if (pair? xs)
(cons
(relaxed-deep-map f (car xs))
(relaxed-deep-map f (cdr xs)))
(f xs)))
(define (maybe-append xs ys)
(and xs ys (append xs ys)))
(define (unique xs)
(if (null? xs)
'()
(let ((ys (unique (cdr xs))))
(if (memq (car xs) ys)
ys
(cons (car xs) ys)))))
(define (deep-unique x)
(cond
((and (pair? x) (symbol? (car x)))
(unique (cons (car x) (deep-unique (cdr x)))))
((pair? x)
(deep-unique
(append
(deep-unique (car x))
(deep-unique (cdr x)))))
((symbol? x)
(list x))
(else
'())))
(define (fold-left f y xs)
(if (null? xs)
y
(fold-left
f
(f (car xs) y)
(cdr xs))))
(define (map-values f xs)
(map (lambda (pair) (cons (car pair) (f (cdr pair)))) xs))
(define (filter-values f xs)
(filter (lambda (pair) (f (cdr pair))) xs))
(define (append-multi-map key values xs)
(cons
(cons
key
(unique
(append
values
(cond
((assq key xs) =>
cdr)
(else
'())))))
(filter
(lambda (pair) (not (eq? (car pair) key)))
xs)))
(define (merge-multi-maps xs ys)
(fold-left
(lambda (pair ys)
(append-multi-map (car pair) (cdr pair) ys))
ys
xs))
; TODO Set a true machine epsilon.
(define epsilon
(let ((x (/ 1 10000000 100000000)))
(if (zero? x) 1 x)))
(define (maybe-car expression)
(and (pair? expression) (car expression)))
(define (count-parameters parameters)
(if (pair? parameters)
(+ 1 (count-parameters (cdr parameters)))
0))
(define (parameter-names parameters)
(cond
((pair? parameters)
(cons (car parameters) (parameter-names (cdr parameters))))
((symbol? parameters)
(list parameters))
((null? parameters)
'())
(else
(error "invalid variadic parameter" parameters))))
(define (symbol-append . xs)
(string->symbol (apply string-append (map symbol->string xs))))
(define symbol-name-separator #\#)
; Inclusion
(define (include-files expression)
(deep-map
(lambda (expression)
(if (and
(pair? expression)
(eq? (car expression) 'include))
(cons
'begin
(append-map
(lambda (name)
(with-input-from-file name
(lambda ()
(let loop ()
(let ((value (read)))
(if (eof-object? value)
'()
(cons value (loop))))))))
(cdr expression)))
expression))
expression))
; Library system
;; Types
(define-record-type library
(make-library exports imports body)
library?
(exports library-exports)
(imports library-imports)
(body library-body))
(define-record-type library-context
(make-library-context libraries imported)
library-context?
(libraries library-context-libraries library-context-set-libraries!)
(imported library-context-imported library-context-set-imported!))
(define (library-context-find context name)
(cond
((assoc name (library-context-libraries context)) =>
cdr)
(else
(error "unknown library" name))))
(define (library-context-add! context name library)
(library-context-set-libraries!
context
(cons (cons name library) (library-context-libraries context))))
(define (library-context-import! context name)
(let* ((names (library-context-imported context))
(imported (member name names)))
(unless imported
(library-context-set-imported! context (cons name names)))
(not imported)))
;; Procedures
(define library-symbol-indicator #\%)
(define (resolve-symbol-string name)
(let* ((string (symbol->string name))
(index (memv-index symbol-name-separator (string->list string))))
(if index
(string-copy string (+ index 1))
string)))
(define (built-in-symbol? name)
(let ((name (symbol->string name)))
(equal? (substring name 0 (min 2 (string-length name))) "$$")))
(define (parse-import-set set)
(let loop ((set set) (qualify (lambda (name) name)))
(let ((loop (lambda (qualify) (loop (cadr set) qualify))))
(case (maybe-car set)
((except)
(loop
(let ((names (cddr set)))
(lambda (name)
(if (memq name names)
#f
(qualify name))))))
((only)
(loop
(let ((names (cddr set)))
(lambda (name)
(if (memq name names)
(qualify name)
#f)))))
((prefix)
(loop
(lambda (name)
(qualify (symbol-append (caddr set) name)))))
((rename)
(loop
(lambda (name)
(qualify
(cond
((assq name (cddr set)) =>
cadr)
(else
name))))))
(else
(cons set qualify))))))
(define (resolve-environment-symbols resolve expression)
(relaxed-deep-map
(lambda (value)
(if (symbol? value)
(resolve value)
value))
expression))
(define (expand-library-bodies context names)
(append-map
(lambda (name)
(if (library-context-import! context name)
(let ((library (library-context-find context name)))
(append
(expand-library-bodies context (library-imports library))
(library-body library)))
'()))
names))
(define (collect-imported-names context sets)
(append-map
(lambda (pair)
(append-map
(lambda (names)
(let ((name ((cdr pair) (car names))))
(if name
(list (cons name (cdr names)))
'())))
(library-exports (library-context-find context (car pair)))))
sets))
(define (add-library-definition! context expression)
(define (collect-bodies predicate)
(append-map
cdr
(filter
(lambda (body) (eq? (car body) predicate))
(cddr expression))))
(define sets (map parse-import-set (collect-bodies 'import)))
(define names (collect-imported-names context sets))
(define (resolve-symbol name)
(cond
((built-in-symbol? name)
name)
((assq name names) =>
cdr)
(else
(let ((renamed (string->uninterned-symbol
(string-append
(string library-symbol-indicator symbol-name-separator)
(symbol->string name)))))
(set! names (cons (cons name renamed) names))
renamed))))
(library-context-add!
context
(cadr expression)
(make-library
(map-values
resolve-symbol
(map
(lambda (name)
(if (eq? (maybe-car name) 'rename)
(cons (caddr name) (cadr name))
(cons name name)))
(collect-bodies 'export)))
(map car sets)
(resolve-environment-symbols resolve-symbol (collect-bodies 'begin)))))
; Macro system
;; Types
(define-record-type macro-state
(make-macro-state globals literals static-symbols dynamic-symbols)
macro-state?
(globals macro-state-globals macro-state-set-globals!)
(literals macro-state-literals macro-state-set-literals!)
(static-symbols macro-state-static-symbols macro-state-set-static-symbols!)
(dynamic-symbols macro-state-dynamic-symbols macro-state-set-dynamic-symbols!))
(define-record-type macro-context
(make-macro-context state locals)
macro-context?
(state macro-context-state)
(locals macro-context-locals))
(define (macro-context-append context pairs)
(make-macro-context
(macro-context-state context)
(append pairs (macro-context-locals context))))
(define (macro-context-set-local! context name denotation)
(let ((pair (assq name (macro-context-locals context))))
(when pair (set-cdr! pair denotation))
pair))
(define (macro-context-set-global! context name denotation)
(let ((state (macro-context-state context)))
(macro-state-set-globals!
state
(cons (cons name denotation) (macro-state-globals state)))))
(define (macro-context-append-literal! context name syntax)
(define state (macro-context-state context))
(macro-state-set-literals!
state
(cons
(cons name syntax)
(macro-state-literals state))))
(define (macro-context-append-static-symbol! context symbol)
(define state (macro-context-state context))
(define symbols (macro-state-static-symbols state))
(unless (memq symbol symbols)
(macro-state-set-static-symbols! state (cons symbol symbols))))
(define (macro-context-append-dynamic-symbol! context symbol)
(define state (macro-context-state context))
(define symbols (macro-state-dynamic-symbols state))
(unless (memq symbol symbols)
(macro-state-set-dynamic-symbols! state (cons symbol symbols))))
(define-record-type ellipsis-pattern
(make-ellipsis-pattern element variables)
ellipsis-pattern?
(element ellipsis-pattern-element)
(variables ellipsis-pattern-variables))
(define-record-type literal-pattern
(make-literal-pattern denotation)
literal-pattern?
(denotation literal-pattern-denotation))
(define-record-type ellipsis-match
(make-ellipsis-match value)
ellipsis-match?
(value ellipsis-match-value))
;; Procedures
(define (resolve-denotation context value)
(cond
((assq value (macro-context-locals context)) =>
cdr)
(else
value)))
(define (resolve-denotation-value context value)
(let ((value (resolve-denotation context value)))
(cond
((and
(symbol? value)
(assq value (macro-state-globals (macro-context-state context))))
=>
cdr)
(else
value))))
(define (rename-variable name)
(string->uninterned-symbol
(string-append
(string symbol-name-separator)
(resolve-symbol-string name))))
(define (find-pattern-variables excluded-patterns pattern)
(let loop ((pattern pattern) (variables '()))
(cond
((pair? pattern)
(loop
(car pattern)
(loop
(cdr pattern)
variables)))
((ellipsis-pattern? pattern)
(loop (ellipsis-pattern-element pattern) variables))
((and (symbol? pattern) (not (memq pattern excluded-patterns)))
(cons pattern variables))
(else
variables))))
(define (compile-pattern context ellipsis literals pattern)
(define (compile pattern)
(compile-pattern context ellipsis literals pattern))
(cond
((and
(symbol? pattern)
(memq (resolve-denotation context pattern) literals))
=>
(lambda (pair)
(make-literal-pattern (car pair))))
((not (pair? pattern))
pattern)
((eq? ellipsis (resolve-denotation context (car pattern)))
(cadr pattern))
((and
(pair? (cdr pattern))
(eq? ellipsis (resolve-denotation context (cadr pattern))))
(compile
(cons
(let ((pattern (compile (car pattern))))
(make-ellipsis-pattern
pattern
(find-pattern-variables '() pattern)))
(cddr pattern))))
(else
(cons
(compile (car pattern))
(compile (cdr pattern))))))
(define (match-ellipsis-pattern context pattern expression)
(map-values
make-ellipsis-match
(apply
map
list
(ellipsis-pattern-variables pattern)
(map
(lambda (expression)
(match-pattern context (ellipsis-pattern-element pattern) expression))
expression))))
(define (match-pattern context pattern expression)
(define (match pattern expression)
(match-pattern context pattern expression))
(cond
((symbol? pattern)
(list (cons pattern expression)))
((pair? pattern)
(cond
((ellipsis-pattern? (car pattern))
(let ((length (- (relaxed-length expression) (relaxed-length (cdr pattern)))))
(when (negative? length)
(raise #f))
(append
(match-ellipsis-pattern context (car pattern) (list-head expression length))
(match (cdr pattern) (list-tail expression length)))))
((pair? expression)
(append
(match (car pattern) (car expression))
(match (cdr pattern) (cdr expression))))
(else
(raise #f))))
((literal-pattern? pattern)
(unless (eq?
(literal-pattern-denotation pattern)
(resolve-denotation context expression))
(raise #f))
'())
((equal? pattern expression)
'())
(else
(raise #f))))
(define (fill-ellipsis-template context matches template)
(let* ((matches (filter (lambda (pair) (memq (car pair) (ellipsis-pattern-variables template))) matches))
(singleton-matches (filter-values (lambda (match) (not (ellipsis-match? match))) matches))
(ellipsis-matches (filter-values ellipsis-match? matches))
(template (ellipsis-pattern-element template)))
(when (null? ellipsis-matches)
(error "no ellipsis pattern variables" template))
(apply
append-map
(lambda matches
(fill-template context (append matches singleton-matches) template))
(map ellipsis-match-value (map cdr ellipsis-matches)))))
(define (fill-template context matches template)
(define (fill template)
(fill-template context matches template))
(cond
((and (symbol? template) (assq template matches)) =>
(lambda (pair)
(list (cdr pair))))
((pair? template)
(list
(apply
append
(fill (car template))
(fill (cdr template)))))
((literal-pattern? template)
(list (literal-pattern-denotation template)))
((ellipsis-pattern? template)
(fill-ellipsis-template context matches template))
(else
(list template))))
(define (fill-top-template context matches template)
(car (fill-template context matches template)))
(define (make-transformer context transformer)
(define (resolve value)
(resolve-denotation context value))
(case (resolve (maybe-car transformer))
(($$syntax-rules)
(let ((rules
(delay
(let ((ellipsis (resolve (cadr transformer)))
(literals (map resolve (caddr transformer))))
(map
(lambda (rule)
(let ((rule
(compile-pattern context ellipsis literals rule)))
(append
rule
(map
(lambda (name) (cons name (resolve name)))
(find-pattern-variables
(find-pattern-variables '() (car rule))
(cadr rule))))))
(cdddr transformer))))))
(lambda (context expression)
(let loop ((rules (force rules)))
(unless (pair? rules)
(error "invalid syntax" expression))
(let ((rule (car rules)))
(guard (value
((not value)
(loop (cdr rules))))
(let* ((matches (match-pattern context (car rule) expression))
(template (cadr rule))
(names (cddr rule))
(renames
(map
(lambda (pair)
(let ((name (car pair)))
(cons name (rename-variable name))))
names)))
(values
(fill-top-template context (append renames matches) template)
(macro-context-append
context
(map
(lambda (rename name)
(cons (cdr rename) (cdr name)))
renames
names))))))))))
(else
(error "unsupported macro transformer" transformer))))
; https://www.researchgate.net/publication/220997237_Macros_That_Work
(define (expand-macro context expression)
(define (expand expression)
(expand-macro context expression))
(define (resolve name)
(resolve-denotation-value context name))
(cond
((symbol? expression)
(let ((value (resolve expression)))
(when (procedure? value)
(error "invalid syntax" expression))
(when (and
(symbol? value)
(not (assq expression (macro-context-locals context))))
(macro-context-append-dynamic-symbol! context expression))
value))
((pair? expression)
(case (resolve (car expression))
(($$define)
(let ((name (cadr expression)))
(macro-context-set-global! context name name)
(macro-context-append-static-symbol! context name)
(expand (cons '$$set! (cdr expression)))))
(($$define-syntax)
(let ((name (cadr expression))
(transformer (caddr expression)))
(macro-context-set-global!
context
name
(make-transformer context transformer))
(macro-context-append-literal!
context
name
(relaxed-deep-map
(lambda (value) (resolve-denotation context value))
transformer))
(macro-context-append-static-symbol! context name)
#f))
(($$lambda)
(let* ((parameters (cadr expression))
(context
(macro-context-append
context
(map
(lambda (name) (cons name (rename-variable name)))
(parameter-names parameters))))
; We need to resolve parameter denotations before expanding a body.
(parameters
(relaxed-deep-map
(lambda (name) (resolve-denotation context name))
parameters)))
(list
'$$lambda
parameters
(expand-macro context (caddr expression)))))
(($$let-syntax)
(expand-macro
(macro-context-append
context
(map-values
(lambda (transformer)
(make-transformer context (car transformer)))
(cadr expression)))
(caddr expression)))
(($$letrec-syntax)
(let* ((bindings (cadr expression))
(context
(macro-context-append
context
(map-values
(lambda (transformer) #f)
bindings))))
(for-each
(lambda (pair)
(macro-context-set-local!
context
(car pair)
(make-transformer context (cadr pair))))
bindings)
(expand-macro context (caddr expression))))
(($$quote)
(cons
'$$quote
(relaxed-deep-map
(lambda (value)
(if (symbol? value)
(string->symbol (resolve-symbol-string value))
value))
(cdr expression))))
(($$syntax-error)
(apply error (cadr expression) (cddr expression)))
(else =>
(lambda (value)
(if (procedure? value)
(let-values (((expression context) (value context expression)))
(expand-macro context expression))
(map expand expression))))))
(else
expression)))
; Optimization
(define-record-type optimization-context
(make-optimization-context optimizers literals)
optimization-context?
(optimizers optimization-context-optimizers optimization-context-set-optimizers!)
(literals optimization-context-literals optimization-context-set-literals!))
(define (optimization-context-append! context name optimizer)
(optimization-context-set-optimizers!
context
(cons
(cons name optimizer)
(optimization-context-optimizers context))))
(define (optimization-context-append-literal! context name literal)
(optimization-context-set-literals!
context
(cons
(cons name literal)
(optimization-context-literals context))))
(define make-optimizer
(let ((context
(make-macro-context (make-macro-state '() '() '() '()) '())))
(lambda (optimizer)
(case (car optimizer)
(($$syntax-rules)
(let* ((ellipsis (cadr optimizer))
(literals (caddr optimizer))
(rules
(map
(lambda (rule)
(map
(lambda (pattern)
(compile-pattern context ellipsis literals pattern))
rule))
(cdddr optimizer))))
(lambda (expression)
(let loop ((rules rules))
(if (null? rules)
expression
(guard (value
((not value)
(loop (cdr rules))))
(let ((rule (car rules)))
(fill-top-template
context
(match-pattern context (car rule) expression)
(cadr rule)))))))))
(else
(error "unsupported optimizer" optimizer))))))
(define (optimize-expression optimize expression)
(if (or (not (pair? expression)) (eq? (car expression) '$$quote))
expression
(optimize
(relaxed-map
(lambda (expression) (optimize-expression optimize expression))
expression))))
(define (optimize-custom-expression context expression)
(optimize-expression
(lambda (expression)
(let ((predicate (car expression)))
(cond
((eq? predicate '$$define-optimizer)
(let ((name (cadr expression)))
(optimization-context-append! context name (make-optimizer (caddr expression)))
(optimization-context-append-literal! context name (caddr expression)))
#f)
((assq predicate (optimization-context-optimizers context)) =>
(lambda (pair)
(let ((optimized ((cdr pair) expression)))
(if (equal? optimized expression)
expression
(optimize-custom-expression context optimized)))))
(else
expression))))
expression))
(define (optimize-begin expression)
(optimize-expression
(lambda (expression)
(if (eq? (car expression) '$$begin)
; TODO Define this pass by `define-optimizer`.
(cons '$$begin
(let loop ((expressions (cdr expression)))
(let ((expression (car expressions))
(expressions (cdr expressions)))
(cond
((null? expressions)
(list expression))
((not (pair? expression))
(loop expressions))
((eq? (car expression) '$$begin)
(loop (append (cdr expression) expressions)))
(else
(cons expression (loop expressions)))))))
expression))
expression))
; Free variable analysis
(define (find-free-variables bound-variables expression)
(define (find expression)
(find-free-variables bound-variables expression))
(cond
((pair? expression)
(case (car expression)
(($$lambda)
(filter
(lambda (name)
(memq name bound-variables))
(cadr expression)))
(($$quote)
'())
(else
(unique
(append
(find (car expression))
(find (cdr expression)))))))
((symbol? expression)
(if (memq expression bound-variables)
(list expression)
'()))
(else
'())))
(define (analyze-expressions bound-variables expressions)
(map
(lambda (expression)
(analyze-expression bound-variables expression))
expressions))
(define (analyze-expression bound-variables expression)
(cond
((pair? expression)
(case (car expression)
(($$lambda)
(let* ((parameters (cadr expression))
(body
(analyze-expressions
(unique (append (parameter-names parameters) bound-variables))
(cddr expression))))
(cons
'$$lambda
(cons
(unique
(append-map
(lambda (expression)
(find-free-variables bound-variables expression))
body))
(cons parameters body)))))
(($$quote)
expression)
(else
(cons