syntax.mes: use cond iso if. rode harink
This commit is contained in:
Jan Nieuwenhuizen
parent
341d064a34
commit
6f40e02029
114
syntax.mes
114
syntax.mes
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@ -143,27 +143,27 @@
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,%input))))))
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(define (process-rule rule)
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(if (and (pair? rule)
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(pair? (cdr rule))
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(null? (cddr rule)))
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(let ((pattern (cdar rule))
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(template (cadr rule)))
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`((and ,@(process-match %tail pattern))
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(let* ,(process-pattern pattern
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%tail
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(lambda (x) x))
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,(process-template template
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0
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(meta-variables pattern 0 '())))))
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(cond ((and (pair? rule)
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(pair? (cdr rule))
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(null? (cddr rule)))
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(let ((pattern (cdar rule))
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(template (cadr rule)))
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`((and ,@(process-match %tail pattern))
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(let* ,(process-pattern pattern
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%tail
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(lambda (x) x))
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,(process-template template
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0
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(meta-variables pattern 0 '()))))))
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(syntax-error "ill-formed syntax rule" rule)))
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;; Generate code to test whether input expression matches pattern
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(define (process-match input pattern)
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(cond ((name? pattern)
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(if (member pattern subkeywords)
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`((,%compare ,input (,%rename ',pattern)))
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`()))
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(cond ((member pattern subkeywords)
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`((,%compare ,input (,%rename ',pattern))))
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(#t `())))
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((segment-pattern? pattern)
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(process-segment-match input (car pattern)))
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((pair? pattern)
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@ -178,30 +178,30 @@
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(define (process-segment-match input pattern)
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(let ((conjuncts (process-match '(car l) pattern)))
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(if (null? conjuncts)
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`((list? ,input)) ;+++
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`((let loop ((l ,input))
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(or (null? l)
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(and (pair? l)
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,@conjuncts
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(loop (cdr l)))))))))
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(cond ((null? conjuncts)
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`((list? ,input))) ;+++
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(#t `((let loop ((l ,input))
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(or (null? l)
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(and (pair? l)
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,@conjuncts
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(loop (cdr l))))))))))
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;; Generate code to take apart the input expression
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;; This is pretty bad, but it seems to work (can't say why).
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(define (process-pattern pattern path mapit)
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(cond ((name? pattern)
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(if (memq pattern subkeywords)
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'()
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(list (list pattern (mapit path)))))
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(cond ((memq pattern subkeywords)
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'())
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(#t (list (list pattern (mapit path))))))
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((segment-pattern? pattern)
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(process-pattern (car pattern)
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%temp
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(lambda (x) ;temp is free in x
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(mapit (if (eq? %temp x)
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path ;+++
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`(map (lambda (,%temp) ,x)
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,path))))))
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(mapit (cond ((eq? %temp x)
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path) ;+++
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(#t `(map (lambda (,%temp) ,x)
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,path)))))))
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((pair? pattern)
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(append (process-pattern (car pattern) `(car ,path) mapit)
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(process-pattern (cdr pattern) `(cdr ,path) mapit)))
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@ -213,28 +213,28 @@
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(define (process-template template rank env)
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(cond ((name? template)
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(let ((probe (assq template env)))
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(if probe
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(if (<= (cdr probe) rank)
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template
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(syntax-error "template rank error (too few ...'s?)"
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template))
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`(,%rename ',template))))
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(cond (probe
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(cond ((<= (cdr probe) rank)
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template)
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(#t (syntax-error "template rank error (too few ...'s?)"
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template))))
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(#t `(,%rename ',template)))))
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((segment-template? template)
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(let ((vars
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(free-meta-variables (car template) (+ rank 1) env '())))
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(if (null? vars)
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(syntax-error "too many ...'s" template)
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(let* ((x (process-template (car template)
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(+ rank 1)
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env))
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(gen (if (equal? (list x) vars)
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x ;+++
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`(map (lambda ,vars ,x)
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,@vars))))
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(if (null? (cddr template))
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gen ;+++
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`(append ,gen ,(process-template (cddr template)
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rank env)))))))
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(cond ((null? vars)
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(syntax-error "too many ...'s" template))
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(#t (let* ((x (process-template (car template)
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(+ rank 1)
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env))
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(gen (cond ((equal? (list x) vars)
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x) ;+++
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(#t `(map (lambda ,vars ,x)
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,@vars)))))
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(cond ((null? (cddr template))
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gen) ;+++
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(#t `(append ,gen ,(process-template (cddr template)
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rank env)))))))))
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((pair? template)
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`(cons ,(process-template (car template) rank env)
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,(process-template (cdr template) rank env)))
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@ -245,9 +245,9 @@
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(define (meta-variables pattern rank vars)
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(cond ((name? pattern)
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(if (memq pattern subkeywords)
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vars
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(cons (cons pattern rank) vars)))
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(cond ((memq pattern subkeywords)
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vars)
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(#t (cons (cons pattern rank) vars))))
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((segment-pattern? pattern)
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(meta-variables (car pattern) (+ rank 1) vars))
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((pair? pattern)
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@ -260,11 +260,11 @@
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(define (free-meta-variables template rank env free)
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(cond ((name? template)
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(if (and (not (memq template free))
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(let ((probe (assq template env)))
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(and probe (>= (cdr probe) rank))))
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(cons template free)
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free))
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(cond ((and (not (memq template free))
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(let ((probe (assq template env)))
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(and probe (>= (cdr probe) rank))))
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(cons template free))
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(#t free)))
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((segment-template? template)
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(free-meta-variables (car template)
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rank env
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@ -295,7 +295,7 @@
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((mes:or) #f)
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((mes:or e) e)
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((mes:or e1 e ...) (let ((temp e1))
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(if temp temp (or e ...))))))
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(cond (temp temp) (#t (or e ...)))))))
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(display "(mes:or #f (= 0 1) 'hello-syntax-world): ")
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(display (mes:or #f (= 0 1) 'hello-syntax-world))
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