uif (inputs... condition trueCallable falseCallable -- outputs...)

Inputs

• inputs...: Zero or more objects supplied to the selected branch.
• condition: Known Cond that selects the branch.
• trueCallable: Already-selected Block processed inline when condition is true.
• falseCallable: Already-selected Block processed inline when condition is false.

Outputs

• outputs...: Objects produced by the selected inline branch.

uif selects between two already-selected Block branches by one known Cond object.

The selected branch is processed inline in the current scope. Locals created there remain available afterward.

Only the selected branch is processed. The unselected branch is ignored completely, may be invalid, and no branch-output merge occurs.

Behavior

• Any additional data inputs used by a branch must already be below condition, trueCallable, and falseCallable on the data stack.
• Before the selected branch is processed, condition, trueCallable, and falseCallable are removed from the stack. The selected branch sees only the remaining underlying data stack.
• TRUE selects trueCallable. FALSE selects falseCallable.

Example

{} 0 {} [
  TRUE [
    7 "chosenTrue" def
    "-- true branch --" printCompilerMessage
  ] [
    impossibleName
  ] uif

  FALSE [
    impossibleOtherName
  ] [
    8 "chosenFalse" def
    "-- false branch --" printCompilerMessage
  ] uif

  "-- after uif --" printCompilerMessage
  chosenTrue printStack _:;
  chosenFalse printStack _:;

  "-- no branch merge --" printCompilerMessage
  TRUE [1] [FALSE] uif printStack _:;

  0
] "main" exportFunction

Expected Output During Compilation

-- true branch --
-- false branch --
-- after uif --
7 Cref
8 Cref
-- no branch merge --
1

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.
• 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.
• ucall builtin (inputs... callable -- outputs...) Processes an already-selected Block or known Text inline in the current scope.