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specs.md

@@ -182,6 +182,12 @@ Fixed-size arrays with element type and length.
 ```sx
 buffer : [5]f32 = .[0, 2, 3.5, 4, 0];
 val := buffer[2];  // 3.5
+buffer.len         // 5 (compile-time constant, s32)
+```
+
+Arrays can also be constructed programmatically with the `Array` builtin:
+```sx
+MyArr :: Array(5, s32);   // equivalent to [5]s32
 ```
 
 ### Slice Types
@@ -200,6 +206,23 @@ items.ptr          // raw pointer
 
 Slices support generic type parameters: `[]$T` introduces type parameter `T` inferred from the element type of the argument (array or slice).
 
+### Subslicing
+Arrays, slices, and strings support subslice syntax to create zero-copy views:
+```sx
+arr : [5]s32 = .[3, 1, 4, 1, 5];
+sub := arr[1..4];    // []s32 → [1, 4, 1]
+head := arr[..3];    // []s32 → [3, 1, 4]
+tail := arr[2..];    // []s32 → [4, 1, 5]
+
+msg := "hello world";
+word := msg[6..11];  // string → "world"
+```
+- `expr[start..end]` — elements from `start` (inclusive) to `end` (exclusive)
+- `expr[start..]` — elements from `start` to end
+- `expr[..end]` — elements from beginning to `end`
+- Result type: `[]T` for arrays/slices, `string` for strings
+- No memory allocation — the result points into the original backing storage
+
 ### Vector Types (SIMD)
 LLVM SIMD vectors, parameterized by length and element type.
 ```sx