diff --git a/src/canary/metta_corelib.pl b/src/canary/metta_corelib.pl
index 93b4cf387d6..165596727c7 100755
--- a/src/canary/metta_corelib.pl
+++ b/src/canary/metta_corelib.pl
@@ -135,6 +135,9 @@
 metta_atom_corelib_types( [:, unify, [->, 'Atom', 'Atom', 'Atom', 'Atom', '%Undefined%']]).
 metta_atom_corelib_types( [:, unify, [->, 'Atom', 'Atom', 'Atom', 'Atom', 'Atom']]).
 metta_atom_corelib_types( [:, unquote, [->, '%Undefined%', '%Undefined%']]).
+% metta_atom_corelib_types( [:, stringToChars [-> 'Atom' 'Expression']]).
+% metta_atom_corelib_types( [:, charsToString [-> 'Expression' 'Atom']]).
+% metta_atom_corelib_types( [:, format-args [-> 'Atom' 'Expression' 'Atom']]).
 
 metta_atom_corelib_types( [:, 'get-metatype', [->, 'Atom', 'Atom']]).
 metta_atom_corelib_types( [:, 'get-type0', [->, 'Atom', 'Atom']]).
diff --git a/src/canary/metta_eval.pl b/src/canary/metta_eval.pl
index e395efe1eac..36c4a414a17 100755
--- a/src/canary/metta_eval.pl
+++ b/src/canary/metta_eval.pl
@@ -1182,6 +1182,56 @@
 eval_20(Eq,RetType,Depth,Self,['stringToChars',String],Chars):- !, eval_args(Eq,RetType,Depth,Self,String,SS), string_chars(SS,Chars0), maplist(as_metta_char,Chars0,Chars).
 eval_20(Eq,RetType,Depth,Self,['charsToString',Chars],String):- !, eval_args(Eq,RetType,Depth,Self,Chars,CC), maplist(as_metta_char,CC0,CC), string_chars(String,CC0).
 
+% =================================================================
+% =================================================================
+% =================================================================
+%  FORMAT-ARGS
+% =================================================================
+% =================================================================
+% =================================================================
+
+% We deal with indexing, but not formatting (the stuff following the ':')(yet)
+% https://doc.rust-lang.org/std/fmt/ used as a reference
+
+format_args_get_index([C|FormatRest1], FormatRest2, Index2) :- char_code(C, Ccode), Ccode >= 48, Ccode =< 57, !, % in the range ['0'..'9']
+    Index1 is Ccode-48,
+    format_args_get_index1(FormatRest1, FormatRest2, Index1, Index2).
+format_args_get_index(FormatRest, FormatRest, none).
+
+% have at least one digit already. This is separate from format_args_get_index to distinguish {} and {0} cases
+format_args_get_index1([C|FormatRest1], FormatRest2, Index1, Index3) :- char_code(C, Ccode), Ccode >= 48, Ccode =< 57, !, % in the range ['0'..'9']
+    Index2 is (Index1*10)+(Ccode-48),
+    format_args_get_index1(FormatRest1, FormatRest2, Index2, Index3).
+format_args_get_index1(FormatRest, FormatRest, Index, Index).
+
+% Placeholder to deal with formatting {<n>:<format>} later
+format_args_get_format(FormatRest, FormatRest, _).
+
+format_args_write(Arg,_) :- string(Arg), !, write(Arg).
+format_args_write('#\\'(Arg),_) :- !, write(Arg).
+format_args_write(Arg,_) :- write_src_woi(Arg).
+
+format_args([], _, _).
+format_args(['{','{'|FormatRest], Iterator, Args) :- !, put('{'), format_args(FormatRest, Iterator, Args). % escaped
+format_args(['}','}'|FormatRest], Iterator, Args) :- !, put('}'), format_args(FormatRest, Iterator, Args). % escaped
+format_args(['{'|FormatRest1], Iterator1, Args) :-
+    format_args_get_index(FormatRest1, FormatRest2, Index),
+    format_args_get_format(FormatRest2, ['}'|FormatRest3], Format),
+    % check that the closing '}' is not escaped with another '}'
+    ((FormatRest3=[] ; ((FormatRest3=[C|_],C\='}')) )),
+    % The Rust behaviour of advancing the iterator if an index is not specified
+    (((Index == none))
+        -> ((nth0(Iterator1,Args,Arg),Iterator2 is Iterator1+1))
+        ; ((nth0(Index,Args,Arg), Iterator2 is Iterator1))),
+    format_args_write(Arg,Format),
+    format_args(FormatRest3, Iterator2, Args).
+format_args([C|FormatRest], Iterator, Args) :- put(C), format_args(FormatRest, Iterator, Args).
+
+eval_20(Eq,RetType,Depth,Self,['format-args',Format,Args],Result):- !,
+   eval_args(Eq,RetType,Depth,Self,Format,EFormat),
+   eval_args(Eq,RetType,Depth,Self,Args,EArgs),
+   string_chars(EFormat, FormatChars), user_io(with_output_to(string(Result), format_args(FormatChars, 0, EArgs))).
+%   string_chars(EFormat, FormatChars), wots(Result, format_args(FormatChars, 0, EArgs)).
 
 eval_20(Eq,RetType,_Depth,_Self,['flip'],Bool):-
    ignore(RetType='Bool'), !, as_tf(random(0,2,0),Bool),
diff --git a/src/canary/metta_interp.pl b/src/canary/metta_interp.pl
index 8e8e2fed4b3..c032736ed3b 100755
--- a/src/canary/metta_interp.pl
+++ b/src/canary/metta_interp.pl
@@ -612,6 +612,7 @@
 % conversion between String and List of Chars
 'stringToChars'(String, Chars) :- eval_H(['stringToChars', String], Chars).
 'charsToString'(Chars, String) :- eval_H(['charsToString', Chars], String).
+'format-args'(Format, Args, Result) :- eval_H(['format-args', Format, Args], Result).
 
 % ============================
 % %%%% Random Utilities
diff --git a/src/canary/metta_ontology.pfc.pl b/src/canary/metta_ontology.pfc.pl
index 0c8f156ac30..d34575d5984 100755
--- a/src/canary/metta_ontology.pfc.pl
+++ b/src/canary/metta_ontology.pfc.pl
@@ -461,4 +461,5 @@
 % --- String and Character manipulation ---
 properties('&corelib','stringToChars', [string_operations, qhelp("Convert a string to a list of chars."), string_to_chars]).
 properties('&corelib','charsToString', [string_operations, qhelp("Convert a list of chars to a string."), chars_to_string]).
+properties('&corelib','format-args', [string_operations, qhelp("Generate a formatted string using a format specifier."), format_args]).
 properties('&corelib','flip', [random, qhelp("Return a random boolean."), random_boolean]).
diff --git a/tests/baseline_compat/hyperon-mettalog_sanity/string-tests.metta b/tests/baseline_compat/hyperon-mettalog_sanity/string-tests.metta
index 948d300d24a..9bbbbc24d78 100644
--- a/tests/baseline_compat/hyperon-mettalog_sanity/string-tests.metta
+++ b/tests/baseline_compat/hyperon-mettalog_sanity/string-tests.metta
@@ -1,3 +1,5 @@
+;; String <=> List of Characters
+
 !(assertEqual (stringToChars "xyzzy") ('x' 'y' 'z' 'z' 'y'))
 
 !(assertEqual (charsToString ('x' 'y' 'z' 'z' 'y')) "xyzzy")
@@ -21,3 +23,26 @@
 !(assertEqual (stringToChars " ") (' '))
 
 !(assertEqual (stringToChars (superpose ("ab" "cd" "ef"))) (superpose (('a' 'b') ('c' 'd') ('e' 'f'))))
+
+;; format-args
+
+!(assertEqual (format-args "" (1 2 3)) "")
+
+!(assertEqual (format-args " " (1 2 3)) " ")
+
+!(assertEqual (format-args "{}" (1 2 3)) "1")
+
+!(assertEqual (format-args "{}}" (1 2 3)) "{}")
+
+!(assertEqual (format-args "xyz zy" (1 2 3)) "xyz zy")
+
+!(assertEqual (format-args "Indexed {1} {} {0} {}" (1 2 3)) "Indexed 2 1 1 2")
+
+!(assertEqual (format-args "Different types {} {} {} {} {} {}" (1 "2" 'c' -0.5 atom (1 2 c -0.5 atom))) "Different types 1 2 c -0.5 atom (1 2 c -0.5 atom)")
+
+!(assertEqual (format-args "Two digit index={11}" (0 1 2 3 4 5 6 7 8 9 10 "eleven")) "Two digit index=eleven")
+
+;; malformed examples
+!(assertEqual (format-args "Bad args list {1} {} {0} {}" x) "Bad args list {1} {} {0} {}")
+
+!(assertEqual (format-args "Malformed format}{{}{{{}{} {4} { } {-1} {x} {{{{{{}}}}}}{{{{{}}}}}" ("success1" "success2")) "Malformed format}{}{success1success2 {4} { } {-1} {x} {{{}}}{{{}}}")
diff --git a/tests/baseline_compat/hyperon-mettalog_sanity/string-tests.metta.answers b/tests/baseline_compat/hyperon-mettalog_sanity/string-tests.metta.answers
index 5d7ee096f32..c981c5b1dfc 100644
--- a/tests/baseline_compat/hyperon-mettalog_sanity/string-tests.metta.answers
+++ b/tests/baseline_compat/hyperon-mettalog_sanity/string-tests.metta.answers
@@ -9,3 +9,13 @@
 [()]
 [()]
 [()]
+[()]
+[()]
+[()]
+[()]
+[()]
+[()]
+[()]
+[()]
+[()]
+[()]