keel build

Coming soon

Status: keel build is the future entry point for the native/LLVM AOT backend (see the project’s designs/llvm-compilation.md). The CLI does not produce a binary yet — --emit=kir prints the mid-level IR for the subset of the language that lowers so far, as a preview of the pipeline under construction; every other form of keel build errors. Behind the scenes, that same subset now compiles, links, and runs as a native binary end to end (proven by a dedicated conformance suite comparing its output against the interpreter’s), but this isn’t reachable from the CLI yet — only from the internal keel-codegen/keel-rt-ffi crates. Use keel run to execute programs and keel check to type-check without running.

--emit=kir

Type-checks a single-file program and prints its lowered mid-level IR (KIR) instead of compiling. Everything through M2 of designs/llvm-compilation.md lowers today: int/float/bool/str literals, arithmetic and comparison, if/else, while, for-over-ranges (and for-over-list[T]), let/assignment, task declarations (including default parameter values), direct calls between tasks, calls into std namespaces (io.show, log.*, …), return (including an implicit tail-expression-as-return), named structs (literals, field access, spread-update), simple enums matched via when (both as a statement and as a value-producing expression in let/return position), list[T]/map[str, V]/set[T] containers, nullable types (T?, ??, ?.), string interpolation, and raise/try/catch. Anything else — agents, lambdas, generics, a when-expression in a call-argument or other nested position, map/set mutation — is rejected by name rather than silently dropped or approximated.

use std/io

task sum_upto(n: int) -> int {
  total = 0
  for i in 1..n {
    total += i
  }
  return total
}

io.show(sum_upto(5))

keel build sum.keel --emit=kir

fn sum_upto(n: int) -> int {
  let total: int = 0
  for i in 1..n {
    total = (total + i)
  }
  return total
}

fn <toplevel>() -> none {
  io.show(sum_upto(5))
}

Real programs use agents, which don’t lower yet, so pointing --emit=kir at examples/hello_world.keel (or almost any other shipped example that declares an agent) currently errors by design:

keel build examples/hello_world.keel --emit=kir

Error:   × KIR lowering error at 419..1039: `agent declaration` is not supported by
  │ the scalar-subset KIR lowering (M0)

Without --emit

keel build examples/hello_world.keel

Error:   × native codegen not yet implemented — `keel build` is the future LLVM AOT
  │ backend (designs/llvm-compilation.md); pass --emit=kir to inspect the mid-
  │ level IR, or use `keel run` to execute examples/hello_world.keel

keel build is present in the CLI because the verb is reserved for the native backend. Codegen exists now (see the status note above) but is not yet wired to this command — only the KIR lowering step above is reachable today.