[elpa] externals/dash e870be8 173/439: Add -when-let* and -if-let*

[Phillip Lord]

branch: externals/dash
commit e870be867c8557c7a660a6350336bc9eca0cc101
Author: Emanuel Evans <address@hidden>
Commit: Emanuel Evans <address@hidden>

    Add -when-let* and -if-let*
---
 README.md       |   28 ++++++++++++++++++++++++++--
 dash.el         |   27 +++++++++++++++++++++++++++
 dev/examples.el |    8 ++++++++
 3 files changed, 61 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 9227fad..340d66a 100644
--- a/README.md
+++ b/README.md
@@ -65,7 +65,9 @@ Or you can just dump `dash.el` in your load path somewhere.
 * [->>](#--x-form-rest-more) `(x form &rest more)`
 * [-->](#---x-form-rest-more) `(x form &rest more)`
 * [-when-let](#-when-let-var-val-rest-body) `(var-val &rest body)`
+* [-when-let*](#-when-let-vars-vals-rest-body) `(vars-vals &rest body)`
 * [-if-let](#-if-let-var-val-then-optional-else) `(var-val then &optional 
else)`
+* [-if-let*](#-if-let-vars-vals-then-optional-else) `(vars-vals then &optional 
else)`
 * [!cons](#-cons-car-cdr) `(car cdr)`
 * [!cdr](#-cdr-list) `(list)`
 
@@ -689,7 +691,7 @@ in in second form, etc.
 ### -when-let `(var-val &rest body)`
 
 If `val` evaluates to non-nil, bind it to `var` and execute body.
-`var-val` should be a (var val) pair.
+`var-val` should be a (`var` `val`) pair.
 
 ```cl
 (-when-let (match-index (string-match "d" "abcd")) (+ match-index 2)) ;; => 5
@@ -697,16 +699,38 @@ If `val` evaluates to non-nil, bind it to `var` and 
execute body.
 (--when-let (even? 3) (cat it :a)) ;; => nil
 ```
 
+### -when-let* `(vars-vals &rest body)`
+
+If all `vals` evaluate to true, bind them to their corresponding
+  `vars` and execute body. `vars-vals` should be a list of (`var` `val`)
+  pairs (corresponding to bindings of `let*`).
+
+```cl
+(-when-let* ((x 5) (y 3) (z (+ y 4))) (+ x y z)) ;; => 15
+(-when-let* ((x 5) (y nil) (z 7)) (+ x y z)) ;; => nil
+```
+
 ### -if-let `(var-val then &optional else)`
 
 If `val` evaluates to non-nil, bind it to `var` and do `then`,
-otherwise do `else`.  `var-val` should be a (`var` `val`) pair.
+otherwise do `else`. `var-val` should be a (`var` `val`) pair.
 
 ```cl
 (-if-let (match-index (string-match "d" "abc")) (+ match-index 3) 7) ;; => 7
 (--if-let (even? 4) it nil) ;; => t
 ```
 
+### -if-let* `(vars-vals then &optional else)`
+
+If all `vals` evaluate to true, bind them to their corresponding
+  `vars` and do `then`, otherwise do `else`. `vars-vals` should be a list
+  of (`var` `val`) pairs (corresponding to the bindings of `let*`).
+
+```cl
+(-if-let* ((x 5) (y 3) (z 7)) (+ x y z) "foo") ;; => 15
+(-if-let* ((x 5) (y nil) (z 7)) (+ x y z) "foo") ;; => "foo"
+```
+
 ### !cons `(car cdr)`
 
 Destructive: Sets `cdr` to the cons of `car` and `cdr`.
diff --git a/dash.el b/dash.el
index 2c3c120..252dd27 100644
--- a/dash.el
+++ b/dash.el
@@ -696,6 +696,17 @@ VAR-VAL should be a (VAR VAL) pair."
        (when ,var
          ,@body))))
 
+(defmacro -when-let* (vars-vals &rest body)
+  "If all VALS evaluate to true, bind them to their corresponding
+  VARS and execute body. VARS-VALS should be a list of (VAR VAL)
+  pairs (corresponding to bindings of `let*')."
+  (if (= (length vars-vals) 1)
+      `(-when-let ,(car vars-vals)
+         ,@body)
+    `(-when-let ,(car vars-vals)
+       (-when-let* ,(cdr vars-vals)
+         ,@body))))
+
 (defmacro --when-let (val &rest body)
   "If VAL evaluates to non-nil, bind it to `it' and execute
 body."
@@ -711,6 +722,18 @@ otherwise do ELSE. VAR-VAL should be a (VAR VAL) pair."
     `(let ((,var ,val))
        (if ,var ,then ,else))))
 
+(defmacro -if-let* (vars-vals then &optional else)
+  "If all VALS evaluate to true, bind them to their corresponding
+  VARS and do THEN, otherwise do ELSE. VARS-VALS should be a list
+  of (VAR VAL) pairs (corresponding to the bindings of `let*')."
+  (let ((first-pair (car vars-vals))
+        (rest (cdr vars-vals)))
+    (if (= (length vars-vals) 1)
+        `(-if-let ,first-pair ,then ,else)
+      `(-if-let ,first-pair
+         (-if-let* ,rest ,then ,else)
+         ,else))))
+
 (defmacro --if-let (val then &optional else)
   "If VAL evaluates to non-nil, bind it to `it' and do THEN,
 otherwise do ELSE."
@@ -718,8 +741,10 @@ otherwise do ELSE."
      (if it ,then ,else)))
 
 (put '-when-let 'lisp-indent-function 1)
+(put '-when-let* 'lisp-indent-function 1)
 (put '--when-let 'lisp-indent-function 1)
 (put '-if-let 'lisp-indent-function 1)
+(put '-if-let* 'lisp-indent-function 1)
 (put '--if-let 'lisp-indent-function 1)
 
 (defun -distinct (list)
@@ -868,8 +893,10 @@ Returns nil if N is less than 1."
                            "->>"
                            "-->"
                            "-when-let"
+                           "-when-let*"
                            "--when-let"
                            "-if-let"
+                           "-if-let*"
                            "--if-let"
                            "-distinct"
                            "-intersection"
diff --git a/dev/examples.el b/dev/examples.el
index 45ad8bf..67b0dc7 100644
--- a/dev/examples.el
+++ b/dev/examples.el
@@ -282,10 +282,18 @@
   (--when-let (member :b '(:a :b :c)) (cons :d it)) => '(:d :b :c)
   (--when-let (even? 3) (cat it :a)) => nil)
 
+(defexamples -when-let*
+  (-when-let* ((x 5) (y 3) (z (+ y 4))) (+ x y z)) => 15
+  (-when-let* ((x 5) (y nil) (z 7)) (+ x y z)) => nil)
+
 (defexamples -if-let
   (-if-let (match-index (string-match "d" "abc")) (+ match-index 3) 7) => 7
   (--if-let (even? 4) it nil) => t)
 
+(defexamples -if-let*
+  (-if-let* ((x 5) (y 3) (z 7)) (+ x y z) "foo") => 15
+  (-if-let* ((x 5) (y nil) (z 7)) (+ x y z) "foo") => "foo")
+
 (defexamples !cons
   (let (l) (!cons 5 l) l) => '(5)
   (let ((l '(3))) (!cons 5 l) l) => '(5 3))