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Changes to the documentation suggested by O. Andreescu. Thanks!

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This commit is contained in:
Georges Dupéron 2016-10-15 14:56:16 +02:00
parent b645c41b35
commit 8f0bcc61b0
2 changed files with 15 additions and 11 deletions
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3
info.rkt
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@ -5,7 +5,8 @@
"typed-racket-lib"))
(define build-deps '("scribble-lib"
"racket-doc"
"afl"))
"afl"
"typed-racket-doc"))
(define scribblings '(("scribblings/typed-map.scrbl" ())))
(define pkg-desc
(string-append "Type inference helper for map with Typed/Racket."

23
scribblings/typed-map.scrbl
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@ -16,7 +16,8 @@
@defproc[#:kind "syntax"
(map [f (→ A ... B)] [l (Listof A)] ...) (Listof B)]{
Like @orig:map, but with better type inference for Typed Racket.
Like @orig:map from @racketmodname[typed/racket/base], but with better type
inference for Typed Racket.
When @racket[f] is a literal lambda of the form
@racket[(λ (arg ...) body ...)], it is not necessary to specify the type of
@ -27,8 +28,8 @@
(let ([l '(4 5 6)])
(map (λ (x) (* x 2)) l))]
This enables the use of @racket[#,hash-lang afl] for @racket[map] in Typed
Racket.
This enables the use of @racket[#,(hash-lang) #,(racketmodname afl)] for
@racket[map] in Typed Racket.
Furthermore, when @racket[f] is a polymorphic function, type annotations are
not needed:
@ -44,10 +45,11 @@
(eval:error (map car '([a . 1] [b . 2] [c . 3]))))]
When used as an identifier, the @racket[map] macro expands to the original
@orig:map from @racketmodname[racket/base]:
@orig:map from @racketmodname[typed/racket/base]:
@examples[#:eval ((make-eval-factory '(typed-map) #:lang 'typed/racket))
(require (only-in racket/base [map orig:map]))
(eval:alts (require (only-in racket/base [#,orig:map orig:map]))
(require (only-in racket/base [map orig:map])))
(equal? map orig:map)]
Note that the implementation expands to a large expression, and makes use of
@ -60,11 +62,12 @@
output is identical to the input. An unoptimizable guard prevents the
double-reverse from actually being executed, so it does not incur a
performance cost.}
@item{It uses a named let to perform the loop the function @racket[f] is
never passed as an argument to another polymorphic function, and is instead
directly called with the appropriate arguments. The error message
"Polymorphic function `map' could not be applied to arguments" is therefore
not raised.}
@item{It uses a
@seclink["Named_let" #:doc '(lib "scribblings/guide/guide.scrbl")]{named
@racket[let]} to perform the loop. The function @racket[f] is never passed
as an argument to another polymorphic function, and is instead directly
called with the appropriate arguments. The error message ``Polymorphic
function `map' could not be applied to arguments'' is therefore not raised.}
@item{To have the most precise and correct types, it uses a named let with a
single variable containing the list (with the generalized type). An outer let
binds a mutable accumulator, initialized with a single-element list