at for strings, for real

prelude.ld

@@ -44,6 +44,7 @@ fn ordered? {
 	"Returns true if a value is an indexed collection: list or tuple."
 	(coll as :list) -> true
 	(coll as :tuple) -> true
+	(coll as :string) -> true
 	(_) -> false
 }
 
@@ -138,6 +139,7 @@ fn rest {
 	(()) -> ()
 	(xs as :list) -> base :rest (xs)
 	(xs as :tuple) -> base :rest (xs)
+	(xs as :string) -> base :str_slice (xs, 1)
 }
 
 fn inc {
@@ -629,10 +631,13 @@ fn at {
 	"Returns the element at index n of a list or tuple, or the byte at index n of a string. Zero-indexed: the first element is at index 0. Returns nil if nothing is found in a list or tuple; returns an empty string if nothing is found in a string."
 	(xs as :list, n as :number) -> base :nth (n, xs)
 	(xs as :tuple, n as :number) -> base :nth (n, xs)
-	(str as :string, n as :number) -> when {
+	(str as :string, n as :number) -> {
-		neg? (n) -> ""
+		let raw = base :nth (n, str)
-		gte? (n, count (str)) -> ""
+		when {
-		true -> base :slice (str, n, inc (n))
+			nil? (raw) -> nil
+			gte? (raw, 128) -> panic! "not an ASCII char"
+			true -> raw
+		}
 	}
 	(_) -> nil
 }
@@ -1283,7 +1288,9 @@ fn apply_command {
 		(:home) -> do state > 
 			assoc (_, :position, (0, 0)) >
 			assoc (_, :heading, 0)
-		(:clear) -> assoc (state, :position, (0, 0))
+		(:clear) -> do state >
+			assoc (state, :position, (0, 0)) >
+			assoc (_, :heading, 0)
 		(:right, turns) -> update (state, :heading, add (_, turns))
 		(:left, turns) -> update (state, :heading, sub (_, turns))
 		(:forward, steps) -> {

src/interpreter.janet

@@ -640,7 +640,7 @@
 #   # (when (has-errors? validated) (break (validated :errors)))
 #   # (def cleaned (get-in parsed [:ast :data 1]))
 #   # # (pp cleaned)
-#   (interpret (parsed :ast) @{:^parent b/ctx})
+#   (interpret (parsed :ast) @{:^parent b/lett})
 #   # (try (interpret (parsed :ast) @{:^parent b/ctx})
 #   #   ([e] (if (struct? e) (error (e :msg)) (error e))))
 #   )

src/ludus.janet

@@ -52,14 +52,14 @@
 (comment
 # (do
  (def source `
-contains? (:d, [:a, :b])
+ add (1, 2)
  `)
  (def out (-> source 
   ludus
   j/decode
   ))
  (setdyn :out stdout)
-(pp out)
+ # (pp out)
  (def console (out "console"))
  (print console)
  (def result (out "result"))

src/parser.janet

@@ -1117,10 +1117,10 @@
 # (do
 (comment
 (def source `
-"{f} a {f}"
+let foo = :bar
 `)
 (def scanned (s/scan source))
 # (print "\n***NEW PARSE***\n")
 (def a-parser (new-parser scanned))
-(def parsed (interpolated a-parser))
+(def parsed (lett a-parser))
 )

src/scanner.janet

@@ -350,6 +350,6 @@
 
 (comment
 # (do
-  (def source "/iii")
+  (def source "add 1 2 () four")
   (scan source)
 )