Add functions, constants

Signed-off-by: Christian Lindig <lindig@gmail.com>

bin/main.ml

@@ -33,7 +33,9 @@ let main () =
       match Tcalc.Parser.main Tcalc.Lexer.token lexbuf with
       | Some seconds -> result seconds
       | None -> ()
-    with _ -> Printf.printf "syntax error in \"%s\"\n%!" input
+    with
+    | Failure msg -> Printf.printf "syntax error in \"%s\": %s\n%!" input msg
+    | _ -> Printf.printf "syntax error in \"%s\"\n%!" input
   in
   repl "tcalc> " calc
 

lib/parser.mly

@@ -5,11 +5,28 @@ let fail fmt = Printf.ksprintf failwith fmt
 
 let t = Hashtbl.create 10
 
+let () = List.iter (fun (id, num) -> Hashtbl.replace t id num)
+  [ ("e", Float.exp 1.0)
+  ; ("pi", Float.pi)
+  ]
+
 let add id num = Hashtbl.replace t id num
+
 let lookup id = Hashtbl.find_opt t id |> function
   | Some v -> v
   | None -> fail "unknown value %s" id
 
+let apply f args = match f, args with
+  | "log10", [x] -> Float.log10 x
+  | "log", [x] -> Float.log x
+  | "logn", [x; y] -> Float.log x /. Float.log y
+  | "sin", [x] -> Float.sin x
+  | "cos", [x] -> Float.cos x
+  | "tan", [x] -> Float.tan x
+  | "abs", [x] -> Float.abs x
+  | id, [] -> lookup id
+  | id, _ -> fail "function %s/%d is unknown" id (List.length args)
+
 %}
 
 %token <float> NUM
@@ -19,8 +36,9 @@ let lookup id = Hashtbl.find_opt t id |> function
 %token EQUAL EOL
 %left PLUS MINUS        /* lowest precedence */
 %left TIMES DIV         /* medium precedence */
-%nonassoc UMINUS        /* highest precedence */
 %right CARET
+%left ID
+%nonassoc LPAREN NUM UMINUS
 
 %start main             /* the entry point */
 %type <float option> main
@@ -35,9 +53,14 @@ stmt:
     ID EQUAL expr           { add $1 $3; $3 }
 ;
 
+app:
+    ID       %prec ID       { ($1, []) }
+  | app expr %prec ID       { match $1 with (f, args) -> (f, $2 :: args) } 
+  ;
+
 expr:
     NUM                     { $1 }
-  | ID                      { lookup $1 }
+  | app %prec ID            { match $1 with (f, args) -> apply f (List.rev args)}
   | LPAREN expr RPAREN      { $2 }
   | expr PLUS expr          { $1 +. $3 }
   | expr MINUS expr         { $1 -. $3 }

tcalc.opam

@@ -1,11 +1,10 @@
+# This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
 synopsis: "Minimal desktop calculator for timestamps"
-description: """\
-TCalc implements a minimal desktop calculator that in addition to
-floating point numbers recognises durations in hh:min:sec format and
-converts them to seconds. This can simplify time-based calculations."""
-maintainer: "Christian Lindig <lindig@gmail.com>"
-authors: "Christian Lindig <lindig@gmail.com>"
+description:
+  "TCalc implements a minimal desktop calculator that in addition to floating point numbers recognises durations in hh:min:sec format and converts them to seconds. This can simplify time-based calculations."
+maintainer: ["Christian Lindig <lindig@gmail.com>"]
+authors: ["Christian Lindig <lindig@gmail.com>"]
 license: "Unlicense"
 homepage: "https://github.com/lindig/tcalc"
 bug-reports: "https://github.com/lindig/tcalc/issues"