Joseph Ferano
9ce51ba94e
as-slice was a warning, not an operation. The input type already decides which of the two things happens — a Vec can only be borrowed, an array or a string can only be viewed, and no call site picks between them — so the second name expressed no choice a reader could make. And it warned at the moment the view is taken, which is the one moment nothing is wrong; the danger arrives later, at the push. slice now takes a Vec at all three arities and as-slice is gone. (slice v lo) was free, and is the arity the Vec never had: the runtime already reads a hi of -1 as "to the end", so the tail form passes the caller's lo and the same -1 — no slot, no length read, no second evaluation. The merge is entirely in the checker; the Vec path builds the flan_vec_as_slice call it always built and neither backend has a line about any of it. A Vec a call returned is refused at every arity, and not for the array's reason. (slice (mk)) over an array dangles. (slice (make-vec)) does not — the storage outlives the expression — but the header is a temporary, so nothing can ever free the block. The refusal says that and names the let. The name's own refusal sits in ordinary_call after every table, so a program that defines an as-slice still reaches its own. It reads for somebody who has never heard of the old name and writes the call back out, spelling each argument that is a name or a number. The warning moved to where it bites: BUILT.md gains a section beside the Vec table and the push row points at it, spec-memory.md's Borrowing says the same. Investigated and deliberately not built — a diagnostic for a live view at the push. (reserve v 100) then a slice, a push and a read is correct code under the contract the spec chose, so any flag on it is a false positive by the language's own semantics rather than by an approximation. FIX.org has the finding and the syntactic sketch that does not work.
55 lines
2.0 KiB
Markdown
55 lines
2.0 KiB
Markdown
# Overview — superseded
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This was the first brainstorm. It is kept for history and is **no longer
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accurate**. Read instead:
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- `../plan.org` — the design, the build sequence, and the open decisions
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- `../spec-memory.md` — ownership, containers, places, generics, function values
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- `../spec-conditions.md` — conditions and restarts, operational semantics
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- `../sand.flan` — the first acceptance program
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- `../syntax-sketch.flan` — the syntax, annotated with the decisions above
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## What changed since
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| This document said | Now |
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|---|---|
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| "C-like with Roc syntax" | S-expressions, Clojure's brackets; C's value model |
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| "Start with interpreter, output C later" | Frontend → typed IR → LLVM IR as text → `clang`. An interpreter is acceptable for milestone 2 only |
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| "lists, slice, fixed-length array, matrices" | Four container types, distinct ownership: `[n T]`, `[T]`, `(Vec T)`, `(Map K V)` — see spec-memory.md |
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| `arr[4]`, `arr[1..]` index syntax | `(at a i)`, `(slice a lo hi)` — no infix, no bracket indexing |
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| `const by default?` | Locals are assignable places; parameters are not; `const` qualifies slices and pointers |
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| Rust-style iterator chains ending in `.collect()` | `->>` threading over slices; every collecting operation allocates from an explicit allocator, usually the frame arena |
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| `Ptr a` | Kept, as `(Ptr a)`. Cross-references use `(Handle a)` instead |
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| option/result in the stdlib | Kept, and layered with conditions — see plan.org "Error handling, layered" |
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## Original text
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```
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Concepts:
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- Primitives
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- u8, i32, f32, bool, char
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- lists, slice, fixed-length array builtin, matrices
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- Control flow
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- for, while, break
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- Structs & tuples
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- Let bindings
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- `Ptr a`
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- Pattern matching
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- ADTs
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- Mutability
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- const by default?
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- Functions
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- Array syntax
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- ranges `arr[1..]`, `arr[..3]`
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- index `arr[4]`
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- Stdlib
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- string
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- vec/dynarray
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- hashtable
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- option/result
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C-like with Roc syntax.
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Start with interpreter. Output C later down the track
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```
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