aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorJJ2024-05-15 19:50:49 +0000
committerJJ2024-05-15 19:50:49 +0000
commit96c99cb83cc0e4dd677b68c51c3865fb2d5ae838 (patch)
tree40734e8f87f5086e46c6d39712c0302bb2e6fbf8
parentd4e9b112250f65493020845b6f74aaf839407d7b (diff)
stlc-let: fixes to check/infer functions
-rw-r--r--stlc-let.rkt21
1 files changed, 16 insertions, 5 deletions
diff --git a/stlc-let.rkt b/stlc-let.rkt
index 1c2453f..82d7a5f 100644
--- a/stlc-let.rkt
+++ b/stlc-let.rkt
@@ -46,14 +46,22 @@
(match with
[`(→ ,a ,b) (check body b (dict-set ctx id a))]
[_ (err (format "expected → type to check λ with but received ~a" with))])]
+ [`((λ ,id ,body) ,arg)
+ (note "unable to check arg type from λ lacking annotation")
+ (check body with ctx)] ; hmm
+ [`(λ ,id (: ,type) ,body)
+ (and (check `(λ ,id ,body) type ctx) (equiv with type))]
[`((λ ,id (: (→ ,a ,b)) ,body) ,arg)
(and (check arg a ctx) (equiv with b)
(check `(λ ,id ,body) `(→ ,a ,b) (dict-set ctx id a)))]
- [`(let ,id ,expr ,body) ; desugaring
+ ; desugaring and error handling
+ [`(let ,id ,expr ,body)
(check `((λ ,id ,body) ,expr) with ctx)]
[`(let ,id (: ,type) ,expr ,body)
(check `((λ ,id (: ,type) ,body) ,expr) with ctx)]
- [`((λ ,id ,body) (: ,type) ,arg) ; error handling
+ [`(λ ,id (: ,type) ,body)
+ (err (format "expected → type on λ but received ~a" type))]
+ [`((λ ,id (: ,type) ,body) ,arg)
(err (format "expected → type on λ but received ~a" type))]
[expr (err (format "inferring an unknown expression ~a" expr))]))
@@ -73,7 +81,7 @@
[`((λ ,id ,body) ,arg)
(infer body (dict-set ctx id (infer arg ctx)))]
[`(λ ,id (: (→ ,a ,b)) ,body)
- (note "arg types are unable to be inferred")
+ (note "unable to infer arg type from λ lacking annotation")
(if (check body b (dict-set ctx id a))
`(→ ,a ,b)
(err (format "inferred return type of ~a does not match annotated type ~a"
@@ -88,8 +96,11 @@
[`(let ,id (: ,type) ,expr ,body)
(infer `((λ ,id (: ,type) ,expr) ,body) ctx)]
[`(λ ,id ,body) ; error handling
- (err "unable to infer type from a function")]
- [`(: ,type) (err "inferring from a type annotation")]
+ (err "unable to infer type from λ lacking annotation")] ; hmm
+ [`(λ ,id (: ,type) ,body)
+ (err (format "expected → type on λ but received ~a" type))]
+ [`((λ ,id (: ,type) ,body) ,arg)
+ (err (format "expected → type on λ but received ~a" type))]
[expr (err (format "inferring an unknown expression ~a" expr))]))
(define (dict-get dict key)