Comments and cleanup in pr.bqn

1 files changed, 35 insertions, 27 deletions

diff --git a/src/pr.bqn b/src/pr.bqn
index fd241395..9452fac7 100755
--- a/src/pr.bqn
+++ b/src/pr.bqn
@@ -1,9 +1,12 @@
 #!/usr/bin/env dbqn
 
 # Process BQN runtime
+# r.bqn begins with provided values and defines primitives as it goes.
+# Defining a primitive shadows previous definitions, so earlier uses
+# of the primitive still use the old definition.
+# This is handled by using a new name each time it's defined.
 
-impl ← •FLines "r.bqn"
-
+# All primitives
 chrs←⟨
   "+-×÷⋆√⌊⌈|¬∧∨<>≠=≤≥≡≢⊣⊢⥊∾≍↑↓↕«»⌽⍉/⍋⍒⊏⊑⊐⊒∊⍷⊔!"
   "˙˜˘¨⌜⁼´˝`"
@@ -11,21 +14,8 @@ chrs←⟨
 ⟩
 nc ← ≠¨chrs
 glyphs ⇐ chr ← ∾chrs
-itr ← 0⥊˜≠chr
-
-idChars ← "_¯.π∞"∾∾"0aA"+⟜↕¨10‿26‿26
-
-init ← " "⊸∾¨(/⟜"_"¨nc/0‿1‿1)∾¨(nc/"FMD")∾¨(nc+´⊸↑⥊"ABC"∾⌜•a)
-post ← ∾⟜" "¨/⟜"_"¨nc/0‿0‿1
-out ← init∾¨'0'∾¨post
 
-Inc ← {
-  i←⊑chr⊐𝕩
-  n←0 ⋄ itr↩{n↩1+𝕩}⌾(i⊑⊢)itr
-  out↩((i⊑init)∾('0'+n)∾i⊑post)⌾(i⊑⊢)out
-}
-
-# Required functionality passed in as an argument
+# Provided values, to be passed in through the constants array
 def ← ⟨"Type","Decompose","Glyph","Fill","Log","GroupLen","GroupOrd","_fillBy_"⟩
 keep ← "!+-×÷⋆⌊=≤≢⥊⊑↕⌜`⊘"
 len ⇐ def+○≠keep
@@ -34,20 +24,38 @@ dt ← ⊔⟜⊒ (+´·∧`'_'=0‿¯1⊸⊏)¨ def
 ns ← » ne←+`nc
 kt ← ∾ (ns+≠¨dt) + ⊔⟜⊒ne⍋ki
 
+# Initial primitive replacement names
+init ← (nc/(' '∾¨1‿2/↑"_")∾¨"FMD")∾¨('A'+nc+´⊸↑⥊3∾⌜○↕26)
+post ← nc/(2‿1/↑"_")∾¨' '
+pn ← init∾¨'0'∾¨post
+
+# All replacements: input and output
 chrt ← ⥊¨chr
-in  ← chrt                  ∾ def
-out ↩ ((kt⊏chrt)⌾(ki⊸⊏)out) ∾ (∾ns+dt)⊏chrt
+in  ← chrt                 ∾ def
+out ← ((kt⊏chrt)⌾(ki⊸⊏)pn) ∾ (∾ns+dt)⊏chrt
+# Make a new name for primitive 𝕩
+itr ← 0⥊˜≠chr
+Shadow ← {
+  i←⊑chr⊐𝕩
+  n←0 ⋄ itr↩{n↩1+𝕩}⌾(i⊑⊢)itr
+  out↩((i⊑init)∾('0'+n)∾i⊑post)⌾(i⊑⊢)out
+}
 
+# Does the expression define a primitive?
 E_isdef ← (3≤≠)◶⟨0,∧´⟨chr," ","←↩"⟩∊˜¨3⊸↑⟩
-E_proc ← {
-  q←≠`𝕩='"' ⋄ q∨↩≠`q<𝕩=''' ⋄ f←¬∨`q<𝕩='#'
-  t ← (¯1+`·¬(»f/q)∨·»⊸∧∊⟜idChars)⊸⊔ f/𝕩
-  ∾ (in⊸⊐ ⊑⟜out⍟(<⟜(≠in))¨ ⊢) t
+# Process ordinary expression
+E_nodef ← {
+  idChars ← "_¯.π∞"∾∾"0aA"+⟜↕¨10‿26‿26
+  q←≠`𝕩='"' ⋄ q∨↩≠`q<𝕩=''' ⋄ f←¬∨`q<𝕩='#'  # Quotes and comments
+  t ← (¯1+`·¬(»f/q)∨·»⊸∧∊⟜idChars)⊸⊔ f/𝕩   # Tokenize
+  ∾ (in⊸⊐ ⊑⟜out⍟(<⟜(≠in))¨ ⊢) t            # Replace
 }
-E_redef ← { # handles [fmd] [←↩]
-  tail ← E_proc 3↓𝕩 # must use old def
-  Inc ⊑𝕩
-  (E_proc 1↑𝕩) ∾ "←" ∾ tail
+# Process expression, possibly redefining a primitive
+E_proc ← E_isdef◶E_nodef‿{
+  tail ← E_proc 3↓𝕩                        # RHS
+  Shadow ⊑𝕩                                # New name
+  (E_proc 1↑𝕩) ∾ "←" ∾ tail                # LHS
 }
 
-ref ⇐ ∾∾⟜(@+10)¨ E_isdef◶E_proc‿E_redef¨ impl∾<"⟨"∾"⟩"«⥊","⊸∾˘chr
+rslt ← "⟨"∾"⟩"«∾","⊸∾¨chrt  # Output all primitives
+ref ⇐ ∾∾⟜(@+10)¨ E_proc¨ (•FLines "r.bqn")∾<rslt