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Added match documentation

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William J. Bowman 2016-01-09 04:23:43 -05:00
parent 61e99c8a2e
commit e03cbfc1e4
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1 changed files with 25 additions and 15 deletions
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40
scribblings/stdlib/sugar.scrbl
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@ -4,7 +4,7 @@
"../defs.rkt" "../defs.rkt"
scribble/eval) scribble/eval)
@(define curnel-eval (curnel-sandbox "(require cur/stdlib/bool cur/stdlib/sugar)")) @(define curnel-eval (curnel-sandbox "(require cur/stdlib/nat cur/stdlib/bool cur/stdlib/sugar)"))
@title{Sugar} @title{Sugar}
@ -82,7 +82,6 @@ Like the @racket[elim] provided by @racketmodname[cur/curnel/redex-lang], but su
automatically curries the remaining arguments @racket[e ...]. automatically curries the remaining arguments @racket[e ...].
@examples[#:eval curnel-eval @examples[#:eval curnel-eval
(require cur/stdlib/bool)
(elim Bool Type (lambda (x : Bool) Bool) (elim Bool Type (lambda (x : Bool) Bool)
false false
true true
@ -94,28 +93,40 @@ automatically curries the remaining arguments @racket[e ...].
Like @racket[define], but uses @racket[forall*] instead of @racket[lambda*]. Like @racket[define], but uses @racket[forall*] instead of @racket[lambda*].
} }
@defform[(case e [pattern maybe-IH body] ...) @defform[(match e [pattern body] ...)
#:grammar #:grammar
[(pattern [(pattern
constructor constructor
(code:line) (code:line (constructor (x : t) ...)))]]{
(code:line (constructor (x : t) ...))) A pattern-matcher-like syntax for inductive elimination.
(maybe-IH Does not actually do pattern matching; instead, relies on the
(code:line) constructors patterns being specified in the same order as when the
(code:line IH: ((x : t) ...)))]]{ inductive type was defined.
A pattern-matcher-like syntax for inductive elimination. Actually does not do pattern matching and Inside the @racket[body], @racket[recur] can be used to refer to the
relies on the constructors patterns being specified in the same order as when the inductive type was inductive hypotheses for an inductive argument.
defined. Generates a call to the inductive eliminator for @racket[e].
Currently does not work on inductive type-families as types indices
are not inferred.
@examples[#:eval curnel-eval @examples[#:eval curnel-eval
(require cur/stdlib/nat) (match z
(case z
[z true] [z true]
[(s (n : Nat)) [(s (n : Nat))
IH: ((_ : Bool))
false])] false])]
@examples[#:eval curnel-eval
(match (s z)
[z true]
[(s (n : Nat))
(not (recur n))])]
} }
@defform[(recur id)]{
A form valid only in the body of a @racket[match] clause. Generates a
reference to the induction hypothesis for @racket[x].
}
@defform[(case* type motive-result-type e (parameters ...) motive [pattern maybe-IH body] ...) @defform[(case* type motive-result-type e (parameters ...) motive [pattern maybe-IH body] ...)
#:grammar #:grammar
[(pattern [(pattern
@ -130,7 +141,6 @@ Necessary for more advanced types, like @racket[And], because @racket[case] is n
@margin-note{Don't worry about all that output from requiring prop} @margin-note{Don't worry about all that output from requiring prop}
@examples[#:eval curnel-eval @examples[#:eval curnel-eval
(require cur/stdlib/nat)
(case* Nat Type z () (lambda (x : Nat) Bool) (case* Nat Type z () (lambda (x : Nat) Bool)
[z true] [z true]
[(s (n : Nat)) [(s (n : Nat))