omg i'm text editing

src/cg/01-stdlib.cg

@@ -32,6 +32,18 @@ filter = f list \ list
       | True \ [x, ...filter f xs]
       | False \ filter f xs);
 
+# insertAt : Int \ a \ List a
+insertAt = idx el list \ list
+  | [] \ [el]
+  | [x, ...xs] \ (idx
+    | 0 \ [el, x, ...xs]
+    | n \ [x, ...insertAt (n - 1) el xs]);
+
+insertCharAt = text pos char \
+  before = slice text 0 pos;
+  after = slice text pos (len text);
+  before & char & after;
+
 # updateAt
 updateAt = i f list \ mapWithIndex (x j \
   (i == j | True \ f x | False \ x)

src/cg/06-textEditor.cg

@@ -1,20 +1,46 @@
 textEditor = name \
   # defaults = {};
-
   # c = { ...defaults, ...config };
 
   source = getSource name;
   lines = split "\n" source;
 
-  # clampCursor : State -> State
+  insertChar = char state \
+    newLines = updateAt state.cursorRow (line \
+      insertCharAt line state.cursorCol char
+    ) state.lines;
+
+    { state = state.{ lines = newLines, cursorCol = state.cursorCol + 1 }, emit = [] };
+
+  backspace = state \
+    state.cursorCol == 0
+    | True \ { state = state, emit = [] } # todo, join line, if not at row 0
+    | False \ (
+      newLines = updateAt state.cursorRow (line \
+        before = slice line 0 (state.cursorCol - 1);
+        after = slice line state.cursorCol (len line);
+        before & after) state.lines;
+
+      { state = state.{ lines = newLines, cursorCol = state.cursorCol - 1 }, emit = [] });
+
+  enter = state \
+    line = nth state.cursorRow state.lines ~ unwrapOr "";
+    before = slice line 0 state.cursorCol;
+    after = slice line state.cursorCol (len line);
+
+    newLines = updateAt state.cursorRow (_ \ before) state.lines;
+    newLines2 = insertAt (state.cursorRow + 1) after newLines;
+
+    { state = state.{ lines = newLines2, cursorCol = 0, cursorRow = state.cursorRow + 1 }, emit = [] };
+
   clampCursor = state \
-    line = nth state.cursorRow lines ~ unwrapOr "";
+    line = nth state.cursorRow state.lines ~ unwrapOr "";
 
     newRow = max 0 state.cursorRow;
-    newRow2 = min (len state.lines - 1) (state.cursorRow);
+    newRow2 = min (len state.lines - 1) newRow;
 
     newCol = max 0 (state.cursorCol);
-    newCol2 = min (len line - 1) (state.cursorCol);
+    newCol2 = min (len line - 1) newCol;
 
     state.{ cursorRow = newRow2, cursorCol = newCol2 };
 
@@ -51,17 +77,44 @@ textEditor = name \
       },
 
       update = state event \ event
-        # | Key { key = " " } \ toggleFocused state
-        # | Key { key = "Enter" } \ toggleFocused state
-
         | Key { key = "ArrowDown" } \ downArrow state
-        | Key { key = "j" } \ downArrow state
+        | Key { key = "j" } \ (state.mode
+          | Insert \ insertChar "j" state
+          | Normal \ downArrow state)
+
         | Key { key = "ArrowUp" } \ upArrow state
-        | Key { key = "k" } \ upArrow state
+        | Key { key = "k" } \ (state.mode
+          | Insert \ insertChar "k" state
+          | Normal \ upArrow state)
+
         | Key { key = "ArrowLeft" } \ leftArrow state
-        | Key { key = "h" } \ leftArrow state
+        | Key { key = "h" } \ (state.mode
+          | Insert \ insertChar "h" state
+          | Normal \ leftArrow state)
+
         | Key { key = "ArrowRight" } \ rightArrow state
-        | Key { key = "l" } \ rightArrow state
+        | Key { key = "l" } \ (state.mode
+          | Insert \ insertChar "l" state
+          | Normal \ rightArrow state)
+
+        | Key { key = "i" } \ (state.mode
+          | Insert \ insertChar "i" state
+          | Normal \ { state = state.{ mode = state.mode | Normal \ Insert | _ \ Insert } })
+
+        | Key { key = "Escape" } \ { state = state.{ mode = state.mode | Insert \ Normal | _ \ Normal } }
+
+        | Key { key = "Backspace" } \ (state.mode
+          | Insert \ backspace state
+          | _ \ { state = state, emit = [] })
+
+        | Key { key = "Enter" } \ (state.mode
+          | Insert \ enter state
+          | _ \ { state = state, emit = [] })
+
+        # any other key
+        | Key { key = key, printable = True } \ (state.mode
+          | Insert \ insertChar key state
+          | _ \ { state = state, emit = [] })
 
         | _ \ { state = state, emit = [] },