Implement the 4 empty function bodies in specs/ml/activation/tanh_activation.t27

[gHashTag]

Context

specs/ml/activation/tanh_activation.t27 declares module Tanh in 53 lines. 4 of its functions are declared with a body that holds no statement — a signature and a comment where the implementation belongs.

.t27 is the hand-authored source language. t27c compiles it out to C, Rust, Verilog and Zig. You are writing source, not compiler output, and not prose about an implementation.

Current state — re-run these yourself

$ cd /Users/playom/t27
$ ./target/release/t27c gen specs/ml/activation/tanh_activation.t27 2>&1 | grep -c 'not yet implemented'
4
$ ./target/release/t27c parse specs/ml/activation/tanh_activation.t27 2>&1 | grep -E '^(recovery-events|declarations-swallowed|lexer-discarded-chars):'
recovery-events: 0
declarations-swallowed: 0
lexer-discarded-chars: 0

Use ./target/release/t27c, not the t27c on PATH: the PATH build prints no parse metrics at all, so the grep above returns nothing and an empty result reads as a pass.

What to write

Keep every signature exactly as it is — the signature is the contract. Quoted verbatim from the file:

1. line 22 — fn forward(x: f32) -> f32
2. line 27 — fn forward_batch(input: []f32) -> []f32
3. line 32 — fn derivative(x: f32) -> f32
4. line 37 — fn derivative_from_output(tanh_x: f32) -> f32

The file already has 0 test block(s). Add one for each function you implement; a body with nothing asserting on it is a claim, not a result.

Acceptance criteria

• 1. ./target/release/t27c gen specs/ml/activation/tanh_activation.t27 2>&1 | grep -c 'not yet implemented' prints 0
• 2. with criterion 1 satisfied, ./target/release/t27c parse specs/ml/activation/tanh_activation.t27 2>&1 | grep -E '^(recovery-events|declarations-swallowed|lexer-discarded-chars):' reports 0, 0 and 0
• 3. with criterion 1 satisfied, all 4 names above still exist: grep -cE '^\s*(pub )?fn (forward|forward_batch|derivative|derivative_from_output)\(' specs/ml/activation/tanh_activation.t27 prints 4
• 4. grep -c '^\s*test "' specs/ml/activation/tanh_activation.t27 prints at least 4 (today: 0)

Boundary

specs/ml/activation/tanh_activation.t27