Implement an `asArray` macro

fixes #6563

1 files changed, 29 insertions, 0 deletions

diff --git a/lib/pure/collections/sequtils.nim b/lib/pure/collections/sequtils.nim
index 0eb8e6704..6041f8268 100644
--- a/lib/pure/collections/sequtils.nim
+++ b/lib/pure/collections/sequtils.nim
@@ -20,6 +20,8 @@
 
 include "system/inclrtl"
 
+import macros
+
 when not defined(nimhygiene):
   {.pragma: dirty.}
 
@@ -704,6 +706,29 @@ template newSeqWith*(len: int, init: untyped): untyped =
     result[i] = init
   result
 
+macro asArray*(values: typed, targetType: typedesc): untyped =
+  ## converts a static array to an array of type ``targetType`` by converting
+  ## each value in the array to the specified type.
+  ##
+  ## Example:
+  ##
+  ## .. code-block::
+  ##   let x = asArray([0.1, 1.2, 2.3, 3.4], int)
+  ##   doAssert x is array[4, int]
+  ##
+  ## Short notation for:
+  ##
+  ## .. code-block::
+  ##   let x = [(0.1).int, (1.2).int, (2.3).int, (3.4).int]
+  let tNode = getType(targetType)[1]
+  values.expectKind(nnkBracket)
+  result = newNimNode(nnkBracket, lineInfoFrom=values)
+  for i in 0 ..< len(values):
+    var dot = newNimNode(nnkDotExpr, lineInfoFrom=values[i])
+    dot.add newPar(values[i])
+    dot.add tNode
+    result.add dot
+
 when isMainModule:
   import strutils
   block: # concat test
@@ -992,5 +1017,9 @@ when isMainModule:
     seq2D[0][1] = true
     doAssert seq2D == @[@[true, true], @[true, false], @[false, false], @[false, false]]
 
+  block: # asArray tests
+    let x = asArray([1.2, 2.3, 3.4, 4.5], int)
+    doAssert x is array[4, int]
+
   when not defined(testing):
     echo "Finished doc tests"