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const std = @import("std");
const Type = std.builtin.Type;
fn typeVerify(T: type, expected: anytype) Type {
const expectedType = @TypeOf(expected);
const expectedTypeInfo = @typeInfo(expectedType);
if (expectedTypeInfo != .@"struct")
@compileError("Expected struct or tuple, found " ++ @typeName(expectedType));
const realTypeInfo = @typeInfo(T);
for (expected) |e| {
if(realTypeInfo == e) return realTypeInfo;
}
for (expected) |e|
@compileError("Expected one of " ++ @tagName(e) ++ ", found " ++ @typeName(T));
return realTypeInfo;
}
/// ```zig
/// (fn (fn (b) c, fn (a) b) fn (a) c)
/// ```
/// Function composition
/// Type signature: (a -> b) -> (b -> c) -> (a -> c)
/// `outerFunc` and `innerFunc` are functions of types `b -> c` and `a -> b` respectively
/// Haskell equivalent: `outerFunc . innerFunc`
pub fn compose(
comptime outerFunc: anytype,
comptime innerFunc: anytype
) blk:{
_=typeVerify(@TypeOf(outerFunc), .{ .@"fn" });
_=typeVerify(@TypeOf(innerFunc), .{ .@"fn" });
const out = @typeInfo(@TypeOf(outerFunc)).@"fn".return_type.?;
const in = @typeInfo(@TypeOf(innerFunc)).@"fn".params[0].type.?;
break :blk fn(in) out;
} {
const out = @typeInfo(@TypeOf(outerFunc)).@"fn".return_type.?;
const in = @typeInfo(@TypeOf(innerFunc)).@"fn".params[0].type.?;
return struct {
fn func(input: in) out {
return outerFunc(innerFunc(input));
}
}.func;
}
/// ```zig
/// (fn (Allocator, fn (fn (a) b, []a) error{OutOfMemory}![]b)
/// ```
/// Map a function onto a list of values, allocating space for the new slice
/// Type signature: `(a -> b) -> [a] -> [b]`
/// `func` is of type `a -> b`, where `items` is of type `[a]`.
/// `map` will return a slice of type `[b]`
/// Haskell equivalent: `map func items`
pub fn mapAlloc(
allocator: std.mem.Allocator,
func: anytype,
items: anytype,
) error{OutOfMemory}!blk:{
const funcInfo = typeVerify(@TypeOf(func), .{ .@"fn" });
const itemsInfo = typeVerify(@TypeOf(items), .{ .array, .pointer });
switch (itemsInfo) {
.pointer => |p| if(p.size != .many and p.size != .slice)
@compileError("Expected pointer of size 'many' or 'slice', found " ++ @tagName(p)),
else =>{},
}
break :blk []funcInfo.@"fn".return_type.?;
} {
const funcInfo = typeVerify(@TypeOf(func), .{ .@"fn" });
var result = try allocator.alloc(funcInfo.@"fn".return_type.?, items.len);
for(items, 0..) |item, i|
result[i] = func(item);
return result;
}
/// ```zig
/// (fn (Allocator, fn (fn (a) b, []a, *[]b) void)
/// ```
/// Map a function onto a list of values, using a buffer
/// Type signature: `(a -> b) -> [a] -> [b]`
/// `func` is of type `a -> b`, where `items` is of type `[a]` and `buffer` is a pointer to a value of type `[b]`.
/// Haskell equivalent: `map func items`
pub fn map(
func: anytype,
items: anytype,
buffer: anytype,
) void {
_=typeVerify(@TypeOf(func), .{ .@"fn" });
const itemsInfo = typeVerify(@TypeOf(items), .{ .pointer, .array });
const bufferInfo = typeVerify(@TypeOf(buffer), .{ .pointer });
const bufferChildInfo = typeVerify(bufferInfo.pointer.child, .{ .pointer, .array });
switch (itemsInfo) {
.pointer => |p| if(p.size != .many and p.size != .slice)
@compileError("Expected pointer of size 'many' or 'slice', found '" ++ @tagName(p.size) ++ "'"),
else =>{},
}
switch (bufferChildInfo) {
.pointer => |p| if(p.size != .many and p.size != .slice)
@compileError("Expected pointer of size 'many' or 'slice', found '" ++ @tagName(p.size) ++ "'"),
else =>{},
}
for (items, 0..) |item, i|
buffer.*[i] = func(item);
}
pub fn curry(func: anytype) blk: {
const typeInfo = typeVerify(@TypeOf(func), .{ .@"fn" }).@"fn";
if (typeInfo.params.len == 1)
break :blk @TypeOf(func);
if (typeInfo.params.len == 2)
break :blk fn(typeInfo.params[0].type.?)
fn(typeInfo.params[1].type.?) typeInfo.return_type.?;
if (typeInfo.params.len == 3)
break :blk fn(typeInfo.params[0].type.?)
fn(typeInfo.params[1].type.?)
fn(typeInfo.params[2].type.?) typeInfo.return_type.?;
} {
const typeInfo = typeVerify(@TypeOf(func), .{ .@"fn" }).@"fn";
if (typeInfo.params.len == 1)
return func;
if (typeInfo.params.len == 2)
return struct {
fn funct(arg1: typeInfo.params[0].type.?) fn(typeInfo.params[1].type.?) typeInfo.return_type.? {
return struct {
fn func2(arg2: typeInfo.params[1].type.?) typeInfo.return_type.? {
return func(arg1, arg2);
}
}.func2;
}
}.funct;
if (typeInfo.params.len == 3)
return struct {
fn func1(arg1: typeInfo.params[0].type.?) fn(typeInfo.params[1].type.?) fn(typeInfo.params[2].type.?)
typeInfo.return_type.? {
return struct {
fn func2(arg2: typeInfo.params[1].type.?) fn(typeInfo.params[2].type.?) typeInfo.return_type.? {
return struct {
fn func3(arg3: typeInfo.params[2].type.?) typeInfo.return_type.? {
return func(arg1, arg2, arg3);
}
}.func3;
}
}.func2;
}
}.func1;
}
pub fn curryHelper(func: anytype, args: anytype) blk: {
const typeInfo = typeVerify(@TypeOf(func), .{ .@"fn" }).@"fn";
_=typeVerify(@TypeOf(args), .{ .@"struct" });
if (typeInfo.params.len == 1)
break :blk @TypeOf(func);
const newInfo = std.builtin.Type{
.@"fn" = .{
.calling_convention = typeInfo.calling_convention,
.is_generic = typeInfo.is_generic,
.params = typeInfo.params[1..],
.is_var_args = typeInfo.is_var_args,
.return_type = typeInfo.return_type,
}
};
_=newInfo;
// break :blk fn(typeInfo.params[args.len].type.?) @Type(newInfo);
break :blk type;
} {
const typeInfo = typeVerify(@TypeOf(func), .{ .@"fn" }).@"fn";
const argInfo = typeVerify(@TypeOf(args), .{ .@"struct" }).@"struct";
if (args.len == typeInfo.params.len) return struct {
pub fn funcCurry() typeInfo.return_type.? {
return @call(.auto, func, args);
}
};
const newInfo = std.builtin.Type{
.@"fn" = .{
.calling_convention = typeInfo.calling_convention,
.is_generic = typeInfo.is_generic,
.params = typeInfo.params[1..],
.is_var_args = typeInfo.is_var_args,
.return_type = typeInfo.return_type,
}
};
_=newInfo;
// const newType = @Type(newInfo);
return struct {
pub fn funcCurry(arg: typeInfo.params[0].type.?) type {
var fields: [64]std.builtin.Type.StructField = .{std.builtin.Type.StructField{.name="10",.type=type,.is_comptime=false,.alignment=8,.default_value_ptr=null}} ** 64;
for (argInfo.fields, 0..) |f, i| {
fields[i] = f;
}
var buf2: [3:0]u8 = undefined;
fields[args.len] = .{
.name = blk: {
break :blk try intToStringZ(args.len, &buf2);
},
.type = typeInfo.params[argInfo.fields.len].type.?,
.is_comptime = false,
.alignment = @alignOf(typeInfo.params[0].type.?),
.default_value_ptr = null,
};
const newStruct = std.builtin.Type{
.@"struct" = .{
.backing_integer = argInfo.backing_integer,
.decls = argInfo.decls,
.fields = fields[0..args.len+1],
.is_tuple = argInfo.is_tuple,
.layout = argInfo.layout,
}
};
// std.debug.print("{any}", .{fields[0..3]});
const t = @Type(newStruct);
var newArgs: t = undefined;
for (@typeInfo(t).@"struct".fields, 0..) |f, i| {
if (i == args.len) {
@field(newArgs, f.name) = arg;
} else @field(newArgs, f.name) = args[i];
}
return curryHelper(func, newArgs);
}
};
}
fn intToStringZ(int: u32, buf: []u8) ![:0]u8 {
return try std.fmt.bufPrintZ(buf, "{}", .{int});
}
// TODO: Add
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