nested_function_eval.chr

:- module(nested_function_eval).
:- use_module(library(prelude)).

% Regression test: a function-equation RHS that constructs a list
% whose elements are function calls. Previously, `compileExpr` did not
% recurse through non-function compound heads (here the cons cell), so
% `add1(N)` was left as an opaque `MakeTerm` and the result was the
% partially-evaluated list `[add1(5), add1(5) + 10]` instead of
% `[6, 16]`. Do NOT rewrite this as `cons(add1(N), ...)` — that form
% only works because `cons/2` is itself a function and was the original
% workaround in the typechecker. The point of this test is the bare
% cons-cell form.
:- function add1(int) -> int.
add1(N) -> N + 1.

:- function chain(int) -> list(int).
chain(N) -> [add1(N), add1(N) + 10].

:- chr_constraint go(list(int)).

go(R) <=> R is chain(5).