ucall (inputs... callable -- outputs...)

Inputs

• inputs...: Objects carried below the inline callable.
• callable: Already-selected object or Ref whose dereferenced input is Block or known Text.

Outputs

• outputs...: Objects left by inline processing of callable.

Processes one already-selected Block or known Text inline in the current scope. No name lookup or field selection happens inside the builtin.

Inline processing leaves locals created by the processed code available afterward.

Behavior

• The callable must already be on the data stack.
• Any remaining data inputs required by that callable must already be below it on the data stack.
• Supported inputs are Block and known Text only.
• A known NIL Text input is invalid.
• Stored Block objects are obtained via .@NAME or @NAME when the stored Block itself must be pushed. Plain .NAME or NAME may already process the stored Block before ucall runs. Known Text locals differ: plain mention already pushes the Text object, so textSource ucall is valid.
• Unknown Text is invalid.
• Code objects are invalid.
• Callable Dict objects are invalid, even when the Dict's CALL field is a Block. ucall does not select CALL or evaluate PRE from a Dict input.

Known Text inputs are interpreted as MPL code text and processed inline.

Example

{} 0 {} [
  "-- block uses stack values below it --" printCompilerMessage
  5 [2 +] ucall printStack _:;

  "-- read stored Block value first, then process it inline --" printCompilerMessage
  blockSource: [7 "blockLocal" def];
  @blockSource ucall
  blockLocal printStack _:;

  "-- text uses stack values below it --" printCompilerMessage
  9 «1 +» ucall printStack _:;

  "-- known Text local also processes inline --" printCompilerMessage
  textSource: «8 "textLocal" def»;
  textSource ucall
  textLocal printStack _:;

  0
] "main" exportFunction

Expected Output During Compilation

-- block uses stack values below it --
7
-- read stored Block value first, then process it inline --
7 Cref
-- text uses stack values below it --
10
-- known Text local also processes inline --
8 Cref

See also

• call builtin (inputs... callable -- outputs...) Calls an already-selected Block, Code, callable Dict, or known Text through a call boundary. No selection happens inside the builtin.
• callField builtin (inputs... dict name -- outputs...) Selects a Dict field by known Text name and then applies .NAME-style semantics. Callable fields are called; non-callable fields are read.
• if builtin (inputs... condition trueCallable falseCallable -- outputs...) Selects between two already-selected Block branches by Cond. Unknown conditions require both branches to be compiled and merged.
• loop builtin (inputs... callable -- outputs...) Repeatedly calls one already-selected Block through a call boundary. The run-time repetition invariant is (A -- A Cond): each body call preserves the carried stack’s shape — the number of objects and their schemas — not necessarily their values, and leaves a final Cond; known-condition iterations may add items or change schemas.
• uif builtin (inputs... condition trueCallable falseCallable -- outputs...) Selects between two already-selected Block branches by a known Cond and processes the selected branch inline. No branch-output merge occurs.