Merge commit '95aeb2ebae' as 'third_party/lisp/alexandria'

third_party/lisp/alexandria/functions.lisp

@@ -0,0 +1,161 @@
+(in-package :alexandria)
+
+;;; To propagate return type and allow the compiler to eliminate the IF when
+;;; it is known if the argument is function or not.
+(declaim (inline ensure-function))
+
+(declaim (ftype (function (t) (values function &optional))
+                ensure-function))
+(defun ensure-function (function-designator)
+  "Returns the function designated by FUNCTION-DESIGNATOR:
+if FUNCTION-DESIGNATOR is a function, it is returned, otherwise
+it must be a function name and its FDEFINITION is returned."
+  (if (functionp function-designator)
+      function-designator
+      (fdefinition function-designator)))
+
+(define-modify-macro ensure-functionf/1 () ensure-function)
+
+(defmacro ensure-functionf (&rest places)
+  "Multiple-place modify macro for ENSURE-FUNCTION: ensures that each of
+PLACES contains a function."
+  `(progn ,@(mapcar (lambda (x) `(ensure-functionf/1 ,x)) places)))
+
+(defun disjoin (predicate &rest more-predicates)
+  "Returns a function that applies each of PREDICATE and MORE-PREDICATE
+functions in turn to its arguments, returning the primary value of the first
+predicate that returns true, without calling the remaining predicates.
+If none of the predicates returns true, NIL is returned."
+  (declare (optimize (speed 3) (safety 1) (debug 1)))
+  (let ((predicate (ensure-function predicate))
+	(more-predicates (mapcar #'ensure-function more-predicates)))
+    (lambda (&rest arguments)
+      (or (apply predicate arguments)
+	  (some (lambda (p)
+		  (declare (type function p))
+		  (apply p arguments))
+		more-predicates)))))
+
+(defun conjoin (predicate &rest more-predicates)
+  "Returns a function that applies each of PREDICATE and MORE-PREDICATE
+functions in turn to its arguments, returning NIL if any of the predicates
+returns false, without calling the remaining predicates. If none of the
+predicates returns false, returns the primary value of the last predicate."
+  (if (null more-predicates)
+      predicate
+      (lambda (&rest arguments)
+	(and (apply predicate arguments)
+	     ;; Cannot simply use CL:EVERY because we want to return the
+	     ;; non-NIL value of the last predicate if all succeed.
+	     (do ((tail (cdr more-predicates) (cdr tail))
+		  (head (car more-predicates) (car tail)))
+		 ((not tail)
+		  (apply head arguments))
+	       (unless (apply head arguments)
+		 (return nil)))))))
+
+
+(defun compose (function &rest more-functions)
+  "Returns a function composed of FUNCTION and MORE-FUNCTIONS that applies its
+arguments to to each in turn, starting from the rightmost of MORE-FUNCTIONS,
+and then calling the next one with the primary value of the last."
+  (declare (optimize (speed 3) (safety 1) (debug 1)))
+  (reduce (lambda (f g)
+	    (let ((f (ensure-function f))
+		  (g (ensure-function g)))
+	      (lambda (&rest arguments)
+		(declare (dynamic-extent arguments))
+		(funcall f (apply g arguments)))))
+          more-functions
+          :initial-value function))
+
+(define-compiler-macro compose (function &rest more-functions)
+  (labels ((compose-1 (funs)
+             (if (cdr funs)
+                 `(funcall ,(car funs) ,(compose-1 (cdr funs)))
+                 `(apply ,(car funs) arguments))))
+    (let* ((args (cons function more-functions))
+           (funs (make-gensym-list (length args) "COMPOSE")))
+      `(let ,(loop for f in funs for arg in args
+		   collect `(,f (ensure-function ,arg)))
+         (declare (optimize (speed 3) (safety 1) (debug 1)))
+         (lambda (&rest arguments)
+           (declare (dynamic-extent arguments))
+           ,(compose-1 funs))))))
+
+(defun multiple-value-compose (function &rest more-functions)
+    "Returns a function composed of FUNCTION and MORE-FUNCTIONS that applies
+its arguments to each in turn, starting from the rightmost of
+MORE-FUNCTIONS, and then calling the next one with all the return values of
+the last."
+  (declare (optimize (speed 3) (safety 1) (debug 1)))
+  (reduce (lambda (f g)
+	    (let ((f (ensure-function f))
+		  (g (ensure-function g)))
+	      (lambda (&rest arguments)
+		(declare (dynamic-extent arguments))
+		(multiple-value-call f (apply g arguments)))))
+          more-functions
+          :initial-value function))
+
+(define-compiler-macro multiple-value-compose (function &rest more-functions)
+  (labels ((compose-1 (funs)
+             (if (cdr funs)
+                 `(multiple-value-call ,(car funs) ,(compose-1 (cdr funs)))
+                 `(apply ,(car funs) arguments))))
+    (let* ((args (cons function more-functions))
+           (funs (make-gensym-list (length args) "MV-COMPOSE")))
+      `(let ,(mapcar #'list funs args)
+         (declare (optimize (speed 3) (safety 1) (debug 1)))
+         (lambda (&rest arguments)
+           (declare (dynamic-extent arguments))
+           ,(compose-1 funs))))))
+
+(declaim (inline curry rcurry))
+
+(defun curry (function &rest arguments)
+  "Returns a function that applies ARGUMENTS and the arguments
+it is called with to FUNCTION."
+  (declare (optimize (speed 3) (safety 1)))
+  (let ((fn (ensure-function function)))
+    (lambda (&rest more)
+      (declare (dynamic-extent more))
+      ;; Using M-V-C we don't need to append the arguments.
+      (multiple-value-call fn (values-list arguments) (values-list more)))))
+
+(define-compiler-macro curry (function &rest arguments)
+  (let ((curries (make-gensym-list (length arguments) "CURRY"))
+        (fun (gensym "FUN")))
+    `(let ((,fun (ensure-function ,function))
+           ,@(mapcar #'list curries arguments))
+       (declare (optimize (speed 3) (safety 1)))
+       (lambda (&rest more)
+         (declare (dynamic-extent more))
+         (apply ,fun ,@curries more)))))
+
+(defun rcurry (function &rest arguments)
+  "Returns a function that applies the arguments it is called
+with and ARGUMENTS to FUNCTION."
+  (declare (optimize (speed 3) (safety 1)))
+  (let ((fn (ensure-function function)))
+    (lambda (&rest more)
+      (declare (dynamic-extent more))
+      (multiple-value-call fn (values-list more) (values-list arguments)))))
+
+(define-compiler-macro rcurry (function &rest arguments)
+  (let ((rcurries (make-gensym-list (length arguments) "RCURRY"))
+        (fun (gensym "FUN")))
+    `(let ((,fun (ensure-function ,function))
+           ,@(mapcar #'list rcurries arguments))
+       (declare (optimize (speed 3) (safety 1)))
+       (lambda (&rest more)
+         (declare (dynamic-extent more))
+         (multiple-value-call ,fun (values-list more) ,@rcurries)))))
+
+(declaim (notinline curry rcurry))
+
+(defmacro named-lambda (name lambda-list &body body)
+  "Expands into a lambda-expression within whose BODY NAME denotes the
+corresponding function."
+  `(labels ((,name ,lambda-list ,@body))
+     #',name))