I'm sorry to keep pestering this list, but I'm out of my depth with the
detailed syntax (and semantics) of typed Racket. But I'm doggedly
ploughing on.
I'm having trouble with the 'let' line in the 'pointer-to' function listed
later:
(let ([vt : Ffi-type (cast ((inst hash-ref Ffi-type Ffi-type) type-to-vector
type #f) Ffi-type)])
Yes, there's an unbalanced parenthesis because this sin't the end of the
let-expression.
The error message is
let: expected type-annotated identifier
parsing context:
while parsing annotated-binding
while parsing optionally type-annotated binding in: (vt : Ffi-type (cast
((inst hash-ref Ffi-type Ffi-type) type-to-vector type #f) Ffi-type))
I can't see the error. 'vt : Ffi-type' looks like a type-annotated
identifier to me. And it seems to have the right number of parentheses
in front of it, followed by an expression whose vlue is to be bound to
'vt'.
Here's the function it's part of:
(define (pointer-to [type : T-Type] . [args : T-Size]) : T-Type ; TODO: rename
args to size-args
(if (and (equal? args '(1)) (not (eq? type '_void)))
(mode-dependent-type
`(_ptr i ,type) `(_ptr o ,type))
(case type
((_void) '_pointer/intptr)
((_byte _uint8) (mode-dependent-type
'_string*/utf-8
(if (null? args)
'_bytes
`(_bytes o ,@ args))))
(else
(let ([vt : Ffi-type (cast ((inst hash-ref Ffi-type Ffi-type)
type-to-vector type #f) Ffi-type)])
(if vt
(mode-dependent-type
`(,vt i)
(if (null? args)
vt
`(,vt o ,@ args)))
(mode-dependent-type
`(_vector i ,type)
(if (null? args)
'_pointer
`(_vector o ,type ,@ args)))))))))
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