janet/recursive.janet

@@ -22,9 +22,7 @@
   ~(set ,name (defn ,name ,;forms)))
 
 ### Next: a data structure for a parser
-(defn- new-parser 
+(defn- new-parser [tokens]
- "Creates a new parser data structure to pass around"
- [tokens]
  @{
   :tokens (tokens :tokens)
   :ast @[]
@@ -33,64 +31,42 @@
  })
 
 ### and some helper functions for interfacing with that data structure
-(defn- current 
+(defn- current [parser] 
- "Returns the current token of a parser. If the parser is at the last token, keeps returning the last token."
+ (def curr (get (parser :tokens) (parser :current)))
- [parser] 
+ (if (not curr)
- (def tokens (parser :tokens))
+  (error "no more tokens")
- (get tokens (parser :current) (last tokens)))
+  curr))
 
-(defn- peek 
+(defn- peek [parser] (get (parser :tokens) (inc (parser :current))))
- "Returns the next token of the parser. If the parser is at the last token, keeps returning the last token." 
- [parser] 
- (def tokens (parser :tokens))
- (get tokens (inc (parser :current)) (last tokens)))
 
-(defn- advance 
+(defn- advance [parser] (update parser :current inc))
- "Advances the parser by a token" 
- [parser] 
- (update parser :current inc))
 
-(defn- type 
+(defn- type [token] (get token :type))
- "Returns the type of a token" 
- [token] 
- (get token :type))
 
-(defn- check 
+(defn- check [parser type]
- "Returns true if the parser's current token is one of the passed types"
- [parser type & types]
- (def accepts [type ;types])
  (def current-type (-> parser current (get :type)))
- (has-value? accepts current-type))
+ (= type current-type))
 
 ### Parsing functions
-# forward declarations
+(declare nonbinding binding synthetic)
-(declare simple nonbinding expr toplevel synthetic)
 
 # errors
-# terminators are what terminate expressions
 (def terminators [:break :newline :semicolon :eof])
 
-(defn- terminates? 
+(defn- terminates? [parser]
- "Returns true if the current token in the parser is a terminator"
- [parser]
  (def curr (current parser))
  (def ttype (type curr))
  (has-value? terminators ttype))
 
-# breakers are what terminate panics
 (def breaking [:break :newline :semicolon :comma :eof :then :else])
 
-(defn- breaks? 
+(defn- breaks? [parser]
- "Returns true if the current token in the parser should break a panic"
- [parser]
  (def curr (current parser))
  (def ttype (type curr))
  (has-value? breaking ttype))
 
-(defn- panic 
+(defn- panic [parser message]
- "Panics the parser: starts skipping tokens until a breaking token is encountered. Adds the error to the parser's errors array, and also errors out."
+ # (print "Panic in the parser: " message)
- [parser message]
- (print "Panic in the parser: " message)
  (def origin (current parser))
  (advance parser)
  (def skipped @[origin])
@@ -98,41 +74,16 @@
   (array/push skipped (current parser))
   (advance parser))
  (array/push skipped (current parser))
+ # (advance parser)
  (def err {:type :error :data skipped :token origin :msg message})
  (update parser :errors array/push err)
  (error err))
 
-(defn- expected 
+(defn- expected [parser ttype]
- "Panics the parser with a message: expected {type} got ..."
+ (panic parser (string "expected " ttype ", got " (-> parser current type))))
- [parser ttype & ttypes]
- (def expected (map string [ttype ;ttypes]))
- (def type-msg (string/join expected " | "))
- (panic parser (string "expected {" type-msg "}, got " (-> parser current type))))
 
-(defn- expect 
+(defn- expect [parser type]
- "Panics if the parser's current token is not of type; otherwise does nothing & returns nil"
+ (if-not (check parser type) (expected parser type)))
- [parser type & types]
- (if-not (check parser type ;types) (expected parser type ;types)))
-
-(defn- expect-ret 
- "Same as expect, but captures the error, returning it as a value"
- [parser type]
- (try (expect parser type) ([e] e)))
-
-(defn- capture 
- "Applies the parse function to the parser, returning the parsed AST. If there is a panic, captures the panic and returns it as a value."
- [parse-fn parser]
- (try (parse-fn parser) ([e] e)))
-
-(defn- accept-one
- "Accepts a single token of passed type, advancing the parser if a match, doing nothing if not."
- [parser type]
- (if (check parser type) (advance parser)))
-
-(defn- accept-many
- "Accepts any number of tokens of a passed type, advancing the parser on match until there are no more matches. Does nothing on no match."
- [parser type]
- (while (check parser type) (advance parser)))
 
 # atoms
 (defn- bool [parser]
@@ -269,7 +220,7 @@
  (advance parser)
  ast)
 
-(defn- sett [parser]
+(defn- set [parser]
  (def origin (current parser))
  (advance parser)
  (def ast {:type :set :data @[] :token origin})
@@ -310,75 +261,6 @@
  (advance parser)
  ast)
 
-### conditional forms
-# if {simple} then {nonbinding} else {nonbinding}
-(defn- iff [parser]
- (def ast {:type :if :data @[] :token (current parser)})
- (advance parser) #consume the if
- (array/push (ast :data) (capture simple parser))
- (accept-many parser :newline)
- (if-let [err (expect-ret parser :then)] 
-  (array/push (ast :data) err) 
-  (advance parser))
- (array/push (ast :data) (capture nonbinding parser))
- (accept-many parser :newline)
- (if-let [err (expect-ret parser :else)] 
-  (array/push (ast :data) err)
-  (advance parser))
- (array/push (ast :data) (capture nonbinding parser))
- ast)
-
-### XXX: We've got an off-by-one error here
-# We're expecting a terminator, we panic until we get to a terminator, and we then return back to something that expects a terminator, and now we've started parsing again *at the terminator*
-(defn- terminator [parser]
- (if-not (terminates? parser) 
-  # this line panics, captures the panic, advances the parser, and re-throws the error
-  (try (panic parser "expected terminator") ([e] (advance parser) (error e))))
- (advance parser)
- (while (terminates? parser) (advance parser)))
-
-# {simple} -> {nonbinding} {terminator}
-(defn- when-clause [parser]
- (def clause @[])
- (print "parsing lhs: " (-> parser current type))
- (array/push clause (capture simple parser))
- (print "parsing arrow")
- (if-let [err (expect-ret parser :arrow)] 
-  (array/push clause err)
-  (advance parser))
- (print "accepting newlines")
- (accept-many parser :newline)
- (print "parsing rhs")
- (array/push clause (nonbinding parser))
- (print "parsing terminator")
- (try (terminator parser) ([e] (array/push clause e)))
- clause)
-
-(defn- whenn [parser]
- (def ast {:type :when :data @[] :origin (current parser)})
- (advance parser) # consume cond
- (if-let [err (expect-ret parser :lbrace)]
-  (do
-   (array/push (ast :data) err)
-   (break ast))
-  (advance parser))
- (accept-many parser :newline)
- (while (not (check parser :rbrace :eof))
-  (array/push (ast :data) (capture when-clause parser)))
- (advance parser)
- ast)
-
-(defn- match [parser])
-
-### function forms
-(defn- fnn [parser])
-
-(defn- lambda [parser])
-
-### compoound forms
-(defn- block [parser])
-
-(defn- doo [parser])
 
 ### expressions
 # four levels of expression complexity:
@@ -433,8 +315,8 @@
   :word (word parser)
 
   # conditional forms
-  :if (iff parser)
+  :if (unreachable)
-  :when (whenn parser)
+  :cond (unreachable)
   :match (unreachable)
   :with (unreachable)
 
@@ -454,9 +336,9 @@
 (defrec expr [parser]
  (def curr (current parser))
  (case (type curr)
-  :let (unreachable)
+  :let nil
-  :fn (unreachable)
+  :fn nil
-  :ref (unreachable)
+  :ref nil
   :nil (nill parser)
   :true (bool parser)
   :false (bool parser)
@@ -468,8 +350,8 @@
   :startdict (dict parser)
   :startset (sett parser)
   :word (word parser)
-  :if (iff parser)
+  :if (unreachable)
-  :when (whenn parser)
+  :cond (unreachable)
   :match (unreachable)
   :with (unreachable)
   :do (unreachable)
@@ -479,16 +361,16 @@
 )
 
 (defrec toplevel [parser]
- (def when (current parser))
+ (def curr (current parser))
  (case (type curr)
-  :pkg (unreachable)
+  :pkg nil
-  :ns (unreachable)
+  :ns nil
-  :test (unreachable)
+  :test nil
-  :import (unreachable)
+  :import nil
-  :use (unreachable)
+  :use nil
-  :let (unreachable)
+  :let nil
-  :fn (unreachable)
+  :fn nil
-  :ref (unreachable)
+  :ref nil
   :nil (nill parser)
   :true (bool parser)
   :false (bool parser)
@@ -500,8 +382,8 @@
   :startdict (dict parser)
   :startset (sett parser)
   :word (word parser)
-  :if (iff parser)
+  :if (unreachable)
-  :when (whenn parser)
+  :cond (unreachable)
   :match (unreachable)
   :with (unreachable)
   :do (unreachable)
@@ -510,20 +392,15 @@
  )
 )
 
-(os/cd "janet") # when repl to do relative imports
+(os/cd "janet") # For repl to do relative imports
 (import ./scanner :as s)
 (do
 #(comment
-(def source `when {
+
- foo -> bar quux
+(def scanned (s/scan "#{}"))
- bar -> baz
-}
-`)
-(def scanned (s/scan source))
 (def a-parser (new-parser scanned))
-(def parsed (whenn a-parser))
+(def parsed (nonbinding a-parser))
 (-> parsed)
-# (map (fn [t] (t :type)) (scanned :tokens))
 )
 
 

janet/scanner.janet

@@ -259,12 +259,12 @@
       "\n" (add-token (update scanner :line inc) :newline)
       "\\" (add-token scanner :backslash)
       "=" (add-token scanner :equals)
-      ">" (add-token (add-token scanner :break) :pipeline)
+      ">" (add-token scanner :pipeline)
 
       ## two-character tokens
       ## ->
       "-" (cond
-           (= next ">") (add-token (advance scanner) :arrow)
+           (= next ">") (add-token (advance scanner) :rarrow)
            (digit? next) (add-number char scanner)
            :else (add-error scanner (string "Expected -> or negative number after `-`. Got `" char next "`")))