commit b2fbddcba0604c79994e42484a451cec9efb0853
parent 734dc957e07d113ad57533fff42d91701908c0c1
Author: Suzanne Soy <ligo@suzanne.soy>
Date: Mon, 15 Mar 2021 03:32:36 +0000
Revert "Tried removing "x", I don't like it"
This reverts commit 184886461ef3c5d70f30ba63b7257963f99fb53f.
Diffstat:
| M | envlang.rkt | | | 65 | +++++++++++++++++++++++++++++++---------------------------------- |
1 file changed, 31 insertions(+), 34 deletions(-)
diff --git a/envlang.rkt b/envlang.rkt
@@ -298,22 +298,17 @@ location of expr current-continuation
#;(
;; Using first-class environments and lazy evaluations:
- ;; λ, env, get, push, drop are keywords
+ ;; λ, env, χ, get, push, drop are keywords
;; v-env
- v ::= (\ env e) ;; open term, expects an env to close the term
- || […] ;; env mapping from names to values
+ v ::= (\ env χ e) ;; open term, expects an env to close the term
+ || […] ;; mapping from names to values
|| "str"
|| 0
- || get ;; env → key → value
- || push ;; env → key → value → env
- || drop ;; env → key → env
- || car
- || cdr
- || (list v ...)
+ || get
+ || push
+ || pop
e ::= v
- || (@ e e)
- || env
- || (list e ...)
+ || (@ e e e)
TODO: instead of ad-hoc var-to-string conversion, use a functional env
@@ -323,32 +318,34 @@ TODO: instead of ad-hoc var-to-string conversion, use a functional env
=> environment′ redex′ continuation frames′
;; Primitive application
- APP [E] (@ (\ env e) [E′]) …
- => [E′] e …
+ APP env=E, χ=X (@ (\ env χ e) v-env (\ env () e-arg)) …
+ => env=v-env,χ=(\ env () e-arg) e …
;;---------------------------------------------------------------------------------------------------------------------------
-;; Evaluation of sub-parts of a primitive application
- APP-F [E] (@ e-f e-env) …
- => [E] e-f … [E],(@ _ e-env)
+;; Evaluation of sub-parts of an application
+ APP-F env=E, χ=X (@ e-f e-env e-arg) …
+ => env=E, χ=X e-f … [env=E,χ=X],(@ _ e-env e-arg)
- APP-ENV [E] (@ e-f e-env) …
- => [E] e-env … [E],(@ v-f _ )
+ APP-ENV env=E, χ=X (@ e-f e-env e-arg) …
+ => env=E, χ=X e-env … [env=E,χ=X],(@ v-f _ e-arg)
+
+ APP-ARG env=E, χ=X (@ e-f e-env e-arg) …
+ => env=E, χ=X e-arg … [env=E,χ=X],(@ v-f v-env _ )
;;---------------------------------------------------------------------------------------------------------------------------
-;; Syntactic sugar (insertion of #%app for all parentheses that don't start with @)
- SUGAR-APP [E] ( e-f e-arg ... ) …
- => [E] (@ (@ (@ (@ get env) "#%app") …
- (@ (@ (@ push env) "χ")
- (list (\ env e-f) (\ env e-arg) ...))))
-;; where the default definition of #%app makes this reduce to:
- => env=E′, χ=X (@ e-f env (list (\ env e-arg) ...)) …
-
-;; in particular, SUGAR-APP for lambda-expressions gives
- SUGAR-APP env=E, χ=X (λ var-name e) …
- => env=E′, χ=X (@ (@ (@ get env) "#%app")
- (@ (@ (@ push env) "χ")
- (list (\ env λ) (\ env var-name) (\ env e)))) …
-;; where the default definition of λ reduces to:
+;; Syntactic sugar (insertion of #%app)
+ SUGAR-APP env=E, χ=X (#%app e-f e-arg ) …
+ => env=E′, χ=X (@ (@ (get env "#%app")
+ env
+ (\ env () e-f))
+ env
+ (\ env () e-arg)) …
+;; defaults to:
+ => env=E′, χ=X (@ e-f env (\ env () e-arg)) …
+
+ SUGAR-LAM env=E, χ=X (λ var-name e) …
+ => env=E′, χ=X (#%app (#%app λ var-name) e) …
+;; defaults to:
=> env=E′, χ=X (@ capture
- (push env)
+ env
(λ env χ (@ (λ env χ e)
(add env "var-name" χ)
χ)))
