Add core/result.milch

3 files changed, 38 insertions, 28 deletions

diff --git a/core/common.milch b/core/common.milch
index 55fa2b8..2aa72a2 100644
--- a/core/common.milch
+++ b/core/common.milch
@@ -141,11 +141,18 @@
 (let split-by (\[delim vals]
     (_split-by delim [] vals)))
 
-(let at (\[n seq]
+(let at! (\![n seq]
     (match seq
-        []          (fatal! (fmt "at out of bounds, n: {0}" [n]))
+        []          (fatal! (fmt "at out of bounds, index: {0}" [n]))
         otherwise   (match n
             0           (head seq)
+            otherwise   (at! (- n 1) (tail seq))))))
+
+(let at (\[n seq]
+    (match seq
+        []          (Result/ex (fmt "at out of bounds, index: {0}" [n]))
+        otherwise   (match n
+            0           (Result/ok (head seq))
             otherwise   (at (- n 1) (tail seq))))))
 
 (let maximum (\[vals]
diff --git a/core/maybe.milch b/core/maybe.milch
index ef9e906..eaf2093 100644
--- a/core/maybe.milch
+++ b/core/maybe.milch
@@ -16,29 +16,7 @@
         "Maybe/Just" (f (Maybe/Just/get-value m))
         "Maybe/Nothing" (Maybe/nothing))))
 
-; TESTING
-
-;; (let print-line! (\[s]
-;;     (print! (concat s "\n"))))
-
-;; (let a (Maybe/just 10))
-;; (let b (Maybe/nothing))
-
-;; (Maybe/map (+ 5) a)
-;; (Maybe/map (+ 5) b)
-
-;; (Maybe/and-then (\[n] (Maybe/just (+ n 5))) a)
-;; (Maybe/and-then (\[n] (Maybe/just (+ n 5))) b)
-
-;; (let m (Maybe/just 10))
-;; (match m
-;;     (Maybe/just _)
-;;         (print-line! (fmt "found just {0}!" [(Maybe/Just/get-value m)]))
-;;     (Maybe/nothing)
-;;         (print-line! "found nothing!"))
-
-;; (let m (Maybe/just 10))
-;; (pipe m [
-;;     (Maybe/map (+ 5))
-;;     (Maybe/and-then (\[val] (Maybe/just (- val 3))))
-;; ])
+(let Maybe/default (\[default m]
+    (match (kind m)
+        "Maybe/Just" (ok-f (Maybe/Just/get-value m))
+        "Result/Ex" default)))
diff --git a/core/result.milch b/core/result.milch
new file mode 100644
index 0000000..897a540
--- /dev/null
+++ b/core/result.milch
@@ -0,0 +1,25 @@
+(record Result/Ok value)
+(record Result/Ex value)
+
+(let Result/ok Result/Ok/create)
+(let Result/ex Result/Ex/create)
+
+(let Result/map (\[f m]
+    (match (kind m)
+        "Result/Ok" (Result/ok (f (Result/Ok/get-value m)))
+        "Result/Ex" m)))
+
+(let Result/map-ex (\[f m]
+    (match (kind m)
+        "Result/Ok" m
+        "Result/Ex" (Result/ex (f (Result/Ex/get-value m))))))
+
+(let Result/and-then (\[f m]
+    (match (kind m)
+        "Result/Ok" (f (Result/Ok/get-value m))
+        "Result/Ex" m)))
+
+(let Result/try (\[catch-f m]
+    (match (kind m)
+        "Result/Ok" (Result/Ok/get-value m)
+        "Result/Ex" (catch-f (Result/Ex/get-value m)))))