From fa8991082ab4ca037238cf14cb1cb0c55dec6b44 Mon Sep 17 00:00:00 2001
From: hellerve <veit@veitheller.de>
Date: Thu, 27 Feb 2020 17:22:03 +0100
Subject: [PATCH] initial

---
 README.md  | 21 +++++++++++++++++++++
 infix.carp | 28 ++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+)
 create mode 100644 README.md
 create mode 100644 infix.carp

diff --git a/README.md b/README.md
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+++ b/README.md
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+# infix
+
+A sketch for an infix-to-prefix transformer in Carp (used for match).
+
+It’s based on my sketchy recollection of something I’ve maybe seen in SICP,
+and something I implemented years ago for zepto’s standard library.
+
+It’s mostly instructional and I don’t recommend you actually use it.
+
+## Usage
+
+After loading `infix.carp`, you’ll be able to use it like this:
+
+```clojure
+(infix 10 * 5 + 3 / 12 pow 2)
+; will transform into (+ (* 10 5) (/ 3 (pow 12 2)))
+```
+
+<hr/>
+
+Have fun!
diff --git a/infix.carp b/infix.carp
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+(defndynamic null? [l] (= (length l) 0))
+
+(defndynamic infix-prec [op]
+  (if (Dynamic.or (= op '+) (= op '-)) 1
+    (if (= 'pow op) 3
+      2)))
+
+(defndynamic infix-op [expr operators operands]
+  (infix-parse expr
+               (cdr operators)
+               (cons (list (car operators) (cadr operands) (car operands))
+                     (cddr operands))))
+
+(defndynamic infix-parse [expr operators operands]
+  (if (null? expr)
+    (if (null? operators)
+      (car operands)
+      (infix-op expr operators operands))
+    (if (list? (car expr))
+      (infix:parse (cdr expr) operators (cons (infix:parse (car expr)) operands))
+      (if (symbol? (car expr))
+        (if (Dynamic.or (null? operators)
+                        (> (infix-prec (car expr)) (infix-prec (car operators))))
+          (infix-parse (cdr expr) (cons (car expr) operators) operands)
+          (infix-op expr operators operands))
+        (infix-parse (cdr expr) operators (cons (car expr) operands))))))
+
+(defmacro infix [:rest args] (infix-parse args '() '()))