From 414a68d50ab084dec85dc9a2d4971464b83e4e99 Mon Sep 17 00:00:00 2001
From: Colin Okay <cbeok@protonmail.com>
Date: Mon, 13 Jul 2020 08:32:45 -0500
Subject: initial commit

---
 lambda-tools.asd  | 12 ++++++++++++
 lambda-tools.lisp | 41 +++++++++++++++++++++++++++++++++++++++++
 macros.lisp       | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 package.lisp      |  6 ++++++
 4 files changed, 112 insertions(+)
 create mode 100644 lambda-tools.asd
 create mode 100644 lambda-tools.lisp
 create mode 100644 macros.lisp
 create mode 100644 package.lisp

diff --git a/lambda-tools.asd b/lambda-tools.asd
new file mode 100644
index 0000000..90b2977
--- /dev/null
+++ b/lambda-tools.asd
@@ -0,0 +1,12 @@
+;;;; lambda-tools.asd
+
+(asdf:defsystem #:lambda-tools
+  :description "Describe lambda-tools here"
+  :author "Your Name <your.name@example.com>"
+  :license  "Specify license here"
+  :version "0.0.1"
+  :serial t
+  :depends-on (:alexandria)
+  :components ((:file "package")
+               (:file "macros")
+               (:file "lambda-tools")))
diff --git a/lambda-tools.lisp b/lambda-tools.lisp
new file mode 100644
index 0000000..4b3ec86
--- /dev/null
+++ b/lambda-tools.lisp
@@ -0,0 +1,41 @@
+;;;; lambda-tools.lisp
+
+(in-package #:lambda-tools)
+
+(defun $or (&rest predicates)
+  "Each argument in PREDICATES is a predicate function of one
+argument. Returns a new predicate, call it P, that is the
+disjunction of each of the PREDICATES.
+
+The value of (P X) is the value of the first predicate Q in PREDICATES
+such that (Q X) is non-NIL, or is NIL if none of the PREDICATES return
+non-NIL.
+
+That is, the disjuction of PREDICATES is short-circuiting. If any
+PREDICATES have side effects, they will be executed only if each of
+the preceding predicates in the list returned NIL."
+  (labels ((disj (x preds)
+             (if (null preds) nil
+                 (if-let (res (funcall (car preds) x))
+                   res
+                   (disj x (cdr preds))))))
+    (lambda (x) (disj x predicates))))
+
+(defun $and (&rest predicates)
+  "Each argument in PREDICATES is a predicate function of one
+argument. Returns a new predicate of one argument, call it P, that is
+the conjunction of each of the PREDICATES.
+
+The value of (P X) is NIL if any of the PREDICATES applied to X are
+NIL. Otherwise it is the value of the last member in PREDICATES
+applied to X.
+
+That is, the conjunction of PREDICATES is short-circuiting.  If any
+PREDICATES have side effects, they will be executed only if each of
+the preceding predicates in the list returned non-NIL."
+  (labels ((conj (x preds)
+             (cond ((null preds) t)
+                   ((null (cdr preds)) (funcall (car preds) x))
+                   ((funcall (car preds) x)
+                    (conj x (cdr preds))))))
+    (lambda (x) (conj x predicates))))
diff --git a/macros.lisp b/macros.lisp
new file mode 100644
index 0000000..cee6eb5
--- /dev/null
+++ b/macros.lisp
@@ -0,0 +1,53 @@
+(in-package :lambda-tools)
+
+(eval-when (:compile-toplevel :load-toplevel :execute)
+  (defun is-substitute-var (symbol)
+    (and (symbolp symbol)
+         (eq (elt (symbol-name symbol) 0)
+             #\_))))
+
+
+
+
+
+(defmacro $ (expr)
+"Quickly create functions from an expression EXPR with 'blanks' in
+it. Each blank is a symbol that betins with the underscore _. Symbols
+with the same name are treated as the same variable.
+
+A function is returned, it accepts exactly the number of variables as
+there were unique blanks in the expression. When calling the new
+function, the variables are bound in the order they appeared in EXPR.
+
+> (macroexpand-1 '($ (+ _a (* _b 3) _b (- _a _c) 10)))
+  (LAMBDA (_A _B _C) 
+     (+ _A 
+       (* _B 3) 
+       _B 
+       (- _A _C) 
+       10))
+
+The macro is useful for succinctly passing functions to
+higher order functions:
+
+> (mapcar ($ (+ _ 10)) '(1 2 3 4))
+ (11 12 13 14)
+
+> (let ((elt-num 2))
+    (mapcar ($ (elt _ elt-num)) 
+            (list \"hey dude\" 
+                  #(1 2 3 4)
+                  \"ffffffffff\")))
+ (#\y 3 #\f)
+"
+  (let  ((new-params (list)))
+    (subst-if t (constantly nil) expr
+              :key (lambda (x) (when (is-substitute-var x)
+                                 (pushnew x new-params))))
+    `(lambda ,(reverse  new-params) ,expr)))
+
+
+
+
+
+
diff --git a/package.lisp b/package.lisp
new file mode 100644
index 0000000..0dcbc8f
--- /dev/null
+++ b/package.lisp
@@ -0,0 +1,6 @@
+;;;; package.lisp
+
+(defpackage #:lambda-tools
+  (:use #:cl)
+  (:import-from #:alexandria
+                #:if-let))
-- 
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