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verifier + interpreter: closure-bind ctx arg for srt/map/flt/fld #186

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Merged
danieljohnmorris merged 1 commit into from
May 12, 2026
Merged

verifier + interpreter: closure-bind ctx arg for srt/map/flt/fld #186

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30 changes: 30 additions & 0 deletions examples/closure-bind.ilo
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Original file line number Diff line number Diff line change
@@ -0,0 +1,30 @@
-- Closure-bind: HOFs (srt, map, flt, fld) accept an optional ctx arg
-- that is passed to every invocation of the fn.
--
-- Pattern shown: sort symbols by an external priority lookup map.
-- Without closure-bind, you'd have to zip the priority into each element
-- (records of {sym, pri}) before sorting, then unzip after — recurring
-- per-program tax that closure-bind removes.

-- Key fn: takes element + ctx (the lookup map). Missing keys sort last.
pri sym:t m:M t n>n;r=mget m sym;?r{n v:v;_:99999}

-- 3-arg srt: srt key-fn ctx xs
top pri-map:M t n syms:L t>L t;srt pri pri-map syms

-- Build a small priority map and sort by it.
main>L t;m=mset mmap "a" 2;m=mset m "b" 3;m=mset m "c" 1;top m ["a","b","c"]

-- map closure-bind: enrich each symbol with its price via lookup
look sym:t pm:M t n>n;r=mget pm sym;?r{n v:v;_:0}
prices pm:M t n syms:L t>L n;map look pm syms

prices-demo>L n;m=mset mmap "a" 10;m=mset m "b" 20;prices m ["a","b","a"]

-- engine-skip: vm
-- engine-skip: jit
-- engine-skip: cranelift
-- run: main
-- out: [c, a, b]
-- run: prices-demo
-- out: [10, 20, 10]
73 changes: 56 additions & 17 deletions src/interpreter/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -819,7 +819,7 @@ fn call_function(env: &mut Env, name: &str, args: Vec<Value>) -> Result<Value> {
)),
};
}
if builtin == Some(Builtin::Srt) && args.len() == 2 {
if builtin == Some(Builtin::Srt) && (args.len() == 2 || args.len() == 3) {
let fn_name = resolve_fn_ref(&args[0]).ok_or_else(|| {
RuntimeError::new(
"ILO-R009",
Expand All @@ -829,20 +829,30 @@ fn call_function(env: &mut Env, name: &str, args: Vec<Value>) -> Result<Value> {
),
)
})?;
let items = match &args[1] {
// closure-bind: srt fn ctx xs
let (ctx, list_arg) = if args.len() == 3 {
(Some(args[1].clone()), &args[2])
} else {
(None, &args[1])
};
let items = match list_arg {
Value::List(l) => l.clone(),
other => {
return Err(RuntimeError::new(
"ILO-R009",
format!("srt: second arg must be a list, got {:?}", other),
format!("srt: list arg must be a list, got {:?}", other),
));
}
};
// Compute keys for each item, then sort by key
let mut keyed: Vec<(Value, Value)> = items
.into_iter()
.map(|item| {
let key = call_function(env, &fn_name, vec![item.clone()])?;
let call_args = match &ctx {
Some(c) => vec![item.clone(), c.clone()],
None => vec![item.clone()],
};
let key = call_function(env, &fn_name, call_args)?;
Ok((key, item))
})
.collect::<Result<_>>()?;
Expand Down Expand Up @@ -1390,7 +1400,7 @@ fn call_function(env: &mut Env, name: &str, args: Vec<Value>) -> Result<Value> {
_ => None,
}
}
if builtin == Some(Builtin::Map) && args.len() == 2 {
if builtin == Some(Builtin::Map) && (args.len() == 2 || args.len() == 3) {
let fn_name = resolve_fn_ref(&args[0]).ok_or_else(|| {
RuntimeError::new(
"ILO-R009",
Expand All @@ -1400,22 +1410,32 @@ fn call_function(env: &mut Env, name: &str, args: Vec<Value>) -> Result<Value> {
),
)
})?;
let items = match &args[1] {
// closure-bind: map fn ctx xs
let (ctx, list_arg) = if args.len() == 3 {
(Some(args[1].clone()), &args[2])
} else {
(None, &args[1])
};
let items = match list_arg {
Value::List(l) => l.clone(),
other => {
return Err(RuntimeError::new(
"ILO-R009",
format!("map: second arg must be a list, got {:?}", other),
format!("map: list arg must be a list, got {:?}", other),
));
}
};
let mut result = Vec::with_capacity(items.len());
for item in items {
result.push(call_function(env, &fn_name, vec![item])?);
let call_args = match &ctx {
Some(c) => vec![item, c.clone()],
None => vec![item],
};
result.push(call_function(env, &fn_name, call_args)?);
}
return Ok(Value::List(result));
}
if builtin == Some(Builtin::Flt) && args.len() == 2 {
if builtin == Some(Builtin::Flt) && (args.len() == 2 || args.len() == 3) {
let fn_name = resolve_fn_ref(&args[0]).ok_or_else(|| {
RuntimeError::new(
"ILO-R009",
Expand All @@ -1425,18 +1445,27 @@ fn call_function(env: &mut Env, name: &str, args: Vec<Value>) -> Result<Value> {
),
)
})?;
let items = match &args[1] {
let (ctx, list_arg) = if args.len() == 3 {
(Some(args[1].clone()), &args[2])
} else {
(None, &args[1])
};
let items = match list_arg {
Value::List(l) => l.clone(),
other => {
return Err(RuntimeError::new(
"ILO-R009",
format!("flt: second arg must be a list, got {:?}", other),
format!("flt: list arg must be a list, got {:?}", other),
));
}
};
let mut result = Vec::new();
for item in items {
match call_function(env, &fn_name, vec![item.clone()])? {
let call_args = match &ctx {
Some(c) => vec![item.clone(), c.clone()],
None => vec![item.clone()],
};
match call_function(env, &fn_name, call_args)? {
Value::Bool(true) => result.push(item),
Value::Bool(false) => {}
other => {
Expand All @@ -1449,7 +1478,7 @@ fn call_function(env: &mut Env, name: &str, args: Vec<Value>) -> Result<Value> {
}
return Ok(Value::List(result));
}
if builtin == Some(Builtin::Fld) && args.len() == 3 {
if builtin == Some(Builtin::Fld) && (args.len() == 3 || args.len() == 4) {
let fn_name = resolve_fn_ref(&args[0]).ok_or_else(|| {
RuntimeError::new(
"ILO-R009",
Expand All @@ -1459,18 +1488,28 @@ fn call_function(env: &mut Env, name: &str, args: Vec<Value>) -> Result<Value> {
),
)
})?;
let items = match &args[1] {
// closure-bind: fld fn ctx xs init
let (ctx, list_arg, init) = if args.len() == 4 {
(Some(args[1].clone()), &args[2], args[3].clone())
} else {
(None, &args[1], args[2].clone())
};
let items = match list_arg {
Value::List(l) => l.clone(),
other => {
return Err(RuntimeError::new(
"ILO-R009",
format!("fld: second arg must be a list, got {:?}", other),
format!("fld: list arg must be a list, got {:?}", other),
));
}
};
let mut acc = args[2].clone();
let mut acc = init;
for item in items {
acc = call_function(env, &fn_name, vec![acc, item])?;
let call_args = match &ctx {
Some(c) => vec![acc, item, c.clone()],
None => vec![acc, item],
};
acc = call_function(env, &fn_name, call_args)?;
}
return Ok(acc);
}
Expand Down
120 changes: 111 additions & 9 deletions src/verify.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -657,6 +657,42 @@ fn builtin_check_args(
(Ty::Text, errors)
}
"srt" => {
if arg_types.len() == 3 {
// srt key-fn ctx xs — closure-bind variant: fn takes (elem, ctx)
if let Some(fn_ty) = arg_types.first()
&& !matches!(fn_ty, Ty::Fn(_, _) | Ty::Unknown)
{
errors.push(VerifyError {
code: "ILO-T013",
function: func_ctx.to_string(),
message: format!("'srt' key arg must be a function (F ...), got {fn_ty}"),
hint: Some("pass a function name: srt key-fn ctx xs".to_string()),
span,
is_warning: false,
});
}
// fn must accept 2 args
if let Some(Ty::Fn(params, _)) = arg_types.first()
&& params.len() != 2
{
errors.push(VerifyError {
code: "ILO-T013",
function: func_ctx.to_string(),
message: format!(
"'srt' key fn must take 2 args (elem, ctx) for closure-bind variant, got {} args",
params.len()
),
hint: Some("for srt fn ctx xs, fn must be: F a c b".to_string()),
span,
is_warning: false,
});
}
let ret = match arg_types.get(2) {
Some(ty @ Ty::List(_)) => ty.clone(),
_ => Ty::Unknown,
};
return (ret, errors);
}
if arg_types.len() == 2 {
// srt key-fn xs — sort by key function
if let Some(fn_ty) = arg_types.first()
Expand Down Expand Up @@ -915,7 +951,7 @@ fn builtin_check_args(
}
"map" => {
// map fn:F a b xs:L a → L b
// First arg must be a function type; second must be a list.
// map fn:F a c b ctx:c xs:L a → L b (closure-bind variant)
if let Some(fn_ty) = arg_types.first()
&& !matches!(fn_ty, Ty::Fn(_, _) | Ty::Unknown)
{
Expand All @@ -928,6 +964,23 @@ fn builtin_check_args(
is_warning: false,
});
}
// closure-bind: fn must take 2 args (elem, ctx)
if arg_types.len() == 3
&& let Some(Ty::Fn(params, _)) = arg_types.first()
&& params.len() != 2
{
errors.push(VerifyError {
code: "ILO-T013",
function: func_ctx.to_string(),
message: format!(
"'map' fn must take 2 args (elem, ctx) for closure-bind variant, got {} args",
params.len()
),
hint: Some("for map fn ctx xs, fn must be: F a c b".to_string()),
span,
is_warning: false,
});
}
// Return type: L of the function's return type, or L Unknown
let ret_elem = match arg_types.first() {
Some(Ty::Fn(_, ret)) => *ret.clone(),
Expand All @@ -937,7 +990,7 @@ fn builtin_check_args(
}
"flt" => {
// flt fn:F a b xs:L a → L a
// First arg: function returning bool; second: list.
// flt fn:F a c b ctx:c xs:L a → L a (closure-bind variant)
if let Some(fn_ty) = arg_types.first()
&& !matches!(fn_ty, Ty::Fn(_, _) | Ty::Unknown)
{
Expand All @@ -950,16 +1003,33 @@ fn builtin_check_args(
is_warning: false,
});
}
// Return type: same list type as input
let ret = match arg_types.get(1) {
if arg_types.len() == 3
&& let Some(Ty::Fn(params, _)) = arg_types.first()
&& params.len() != 2
{
errors.push(VerifyError {
code: "ILO-T013",
function: func_ctx.to_string(),
message: format!(
"'flt' fn must take 2 args (elem, ctx) for closure-bind variant, got {} args",
params.len()
),
hint: Some("for flt fn ctx xs, fn must be: F a c b".to_string()),
span,
is_warning: false,
});
}
// Return type: same list type as input (last arg position)
let list_idx = if arg_types.len() == 3 { 2 } else { 1 };
let ret = match arg_types.get(list_idx) {
Some(ty @ Ty::List(_)) => ty.clone(),
_ => Ty::Unknown,
};
(ret, errors)
}
"fld" => {
// fld fn:F a b b xs:L a init:b → b
// First arg: function; second: list; third: initial accumulator.
// fld fn:F a c b b ctx:c xs:L a init:b → b (closure-bind variant)
if let Some(fn_ty) = arg_types.first()
&& !matches!(fn_ty, Ty::Fn(_, _) | Ty::Unknown)
{
Expand All @@ -972,8 +1042,25 @@ fn builtin_check_args(
is_warning: false,
});
}
// Return type: accumulator type (third arg) or function return type
let ret = match arg_types.get(2) {
if arg_types.len() == 4
&& let Some(Ty::Fn(params, _)) = arg_types.first()
&& params.len() != 3
{
errors.push(VerifyError {
code: "ILO-T013",
function: func_ctx.to_string(),
message: format!(
"'fld' fn must take 3 args (acc, elem, ctx) for closure-bind variant, got {} args",
params.len()
),
hint: Some("for fld fn ctx xs init, fn must be: F b a c b".to_string()),
span,
is_warning: false,
});
}
// Return type: accumulator type (last arg) or function return type
let init_idx = if arg_types.len() == 4 { 3 } else { 2 };
let ret = match arg_types.get(init_idx) {
Some(ty) if !matches!(ty, Ty::Unknown) => ty.clone(),
_ => match arg_types.first() {
Some(Ty::Fn(_, ret)) => *ret.clone(),
Expand Down Expand Up @@ -1814,7 +1901,16 @@ impl VerifyContext {
builtin_arity(callee).expect("is_builtin guarantees arity exists");
let arity_ok = if callee == "rnd" {
args.is_empty() || args.len() == 2
} else if callee == "srt" || callee == "rd" {
} else if callee == "srt" {
// srt xs / srt fn xs / srt fn ctx xs
args.len() == 1 || args.len() == 2 || args.len() == 3
} else if callee == "map" || callee == "flt" {
// map fn xs / map fn ctx xs (closure-bind variant)
args.len() == 2 || args.len() == 3
} else if callee == "fld" {
// fld fn xs init / fld fn ctx xs init (closure-bind variant)
args.len() == 3 || args.len() == 4
} else if callee == "rd" {
args.len() == 1 || args.len() == 2
} else if callee == "wr" {
args.len() == 2 || args.len() == 3
Expand All @@ -1830,7 +1926,13 @@ impl VerifyContext {
if !arity_ok {
let arity_desc = if callee == "rnd" {
"0 or 2".to_string()
} else if callee == "srt" || callee == "rd" || callee == "get" {
} else if callee == "srt" {
"1, 2, or 3".to_string()
} else if callee == "map" || callee == "flt" {
"2 or 3".to_string()
} else if callee == "fld" {
"3 or 4".to_string()
} else if callee == "rd" || callee == "get" {
"1 or 2".to_string()
} else if callee == "post" {
"2 or 3".to_string()
Expand Down
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