hi,
when i test at toplevel:
scheme@(guile-user)> (match 1 (1 (define x3) (+ x 1)))
While compiling expression:
Syntax error:
unknown location: definition in expression context, where definitions
are not allowed, in form (define x3)
but i have this code that works well and have definition in match:
(define (assignment-argument-4 container-eval index1-or-keyword-eval
index2-or-keyword-eval index3-or-keyword-eval index4-or-step-eval
expr-eval)
(when (not {(vector? container-eval) or (string? container-eval) or
(array? container-eval) or (growable-vector? container-eval)})
(error "assignment : container type not compatible : " container-eval))
{index1-or-keyword-eval-pos <+ index1-or-keyword-eval}
{index2-or-keyword-eval-pos <+ index2-or-keyword-eval}
{index3-or-keyword-eval-pos <+ index3-or-keyword-eval}
{index4-or-step-eval-pos <+ index4-or-step-eval}
(declare container-length container-copy!)
(if (vector? container-eval)
($>
{container-length <- vector-length}
{container-copy! <- vector-copy!})
($> ;; a string
{container-length <- string-length}
{container-copy! <- string-copy!}))
;; transform the negative indexes in positive ones when not slices
(when {(not (equal? index1-or-keyword-eval-pos slice)) and
{index1-or-keyword-eval-pos < 0}}
{index1-or-keyword-eval-pos <- (container-length container-eval) +
index1-or-keyword-eval-pos})
(when {(not (equal? index2-or-keyword-eval-pos slice)) and
{index2-or-keyword-eval-pos < 0}}
{index2-or-keyword-eval-pos <- (container-length container-eval) +
index2-or-keyword-eval-pos})
(when {(not (equal? index3-or-keyword-eval-pos slice)) and
{index3-or-keyword-eval-pos < 0}}
{index3-or-keyword-eval-pos <- (container-length container-eval) +
index3-or-keyword-eval-pos})
(when {(not (equal? index4-or-step-eval-pos slice)) and
{index4-or-step-eval-pos < 0}}
{index4-or-step-eval-pos <- (container-length container-eval) +
index4-or-step-eval-pos})
(match (list index1-or-keyword-eval-pos index2-or-keyword-eval-pos
index3-or-keyword-eval-pos index4-or-step-eval-pos)
;; T[i1 $ i2 $]
((i1 (? (cut equal? <> slice)) i2 (? (cut equal? <> slice)))
{container-eval[i1 slice i2] <- expr-eval})
;; T[$ i2 $ s3]
;; > {v <+ (vector 1 2 3 4 5 6 7 8 9)}
;; '#(1 2 3 4 5 6 7 8 9)
;; > {v[$ 6 $ 2] <- (vector -1 -2 -3 -4 -5)}
;; > v
;; '#(-1 2 -2 4 -3 6 7 8 9)
(((? (cut equal? <> slice)) i2 (? (cut equal? <> slice)) step-not-used)
(display "we are in match !") (newline)
{step <+ index4-or-step-eval}
(when {step = 0}
(error "assignment : slice step cannot be zero"))
{i <+ 0}
(if {step < 0} ;; with negative index we start at end of vector
(like in Python)
(for ({k <+ i2} {k >= 0} {k <- k + step})
{container-eval[k] <- expr-eval[i]}
{i <- i + 1})
(for ({k <+ 0} {k < i2} {k <- k + step})
{container-eval[k] <- expr-eval[i]}
{i <- i + 1}))
container-eval
)
;; T[i1 $ $ s3]
((i1 (? (cut equal? <> slice)) (? (cut equal? <> slice)) step-not-used)
{step <+ index4-or-step-eval}
;; > {s <+ (string-append "abcdefgh")}
;; "abcdefgh"
;; {s[3 $ $ 2] <- "0000"}
;; > s
;; "abc0e0g0"
(when (= 0 step)
(error "assignment : slice step cannot be zero"))
(let* ((size-input (vector-length container-eval))
(i 0))
(if (< step 0) ;; with negative index we start at end of
vector (like in Python)
(for ((define k (- size-input 1)) (>= k i1) (set! k (+ k step)))
(vector-set! container-eval
k
(vector-ref expr-eval i))
(set! i (+ 1 i)))
(for ({k <+ i1} {k < size-input} {k <- k + step})
(vector-set! container-eval
k
(vector-ref expr-eval i))
{i <- 1 + i})))
container-eval
)
;; T[i1 i2 i3 i4]
((i1 i2 i3 i4)
;; normal case
(if (vector? container-eval)
(function-array-n-dim-set! container-eval expr-eval (reverse
(list i1 i2 i3 i4))) ;;(array-n-dim-set! array value i1 i2)
(srfi25-array-set! container-eval index1-or-keyword-eval
index2-or-keyword-eval index3-or-keyword-eval index4-or-step-eval
expr-eval))
expr-eval ;; returning a value allow the chaining : {T[3 5 6 2]
<- A[4 2 3] <- T[2 5]}
)
) ;; end match
)
scheme@(guile-user)> {v <+ (vector 1 2 3 4 5 6 7 8 9)}
$1 = #(1 2 3 4 5 6 7 8 9)
scheme@(guile-user)> {v[$ 6 $ 2] <- (vector -1 -2 -3 -4 -5)}
we are in match !
$2 = #(-1 2 -2 4 -3 6 7 8 9)
seems that match from toplevel is different than in code.
note: there is no difference in Racket or Kawa , match allow definitions inside.
