Add tasks for all the new languages

Task/Modular-exponentiation/EchoLisp/modular-exponentiation.echolisp

@@ -0,0 +1,22 @@
+(lib 'bigint)
+
+(define a 2988348162058574136915891421498819466320163312926952423791023078876139)
+(define b 2351399303373464486466122544523690094744975233415544072992656881240319)
+(define m 1e40)
+
+(powmod a b m)
+    → 1527229998585248450016808958343740453059
+
+;; powmod is a native function
+;; it could be defined as follows :
+
+(define (xpowmod base exp mod)
+    (define result 1)
+    (while ( !zero? exp)
+        (when (odd? exp) (set! result (% (* result base) mod)))
+    (/= exp 2)
+    (set! base (% (* base base) mod)))
+result)
+
+(xpowmod a b m)
+    → 1527229998585248450016808958343740453059

Task/Modular-exponentiation/Nim/modular-exponentiation.nim

@@ -0,0 +1,18 @@
+import bigints
+
+proc powmod(b, e, m: BigInt): BigInt =
+  assert e >= 0
+  var e = e
+  var b = b
+  result = initBigInt(1)
+  while e > 0:
+    if e mod 2 == 1:
+      result = (result * b) mod m
+    e = e div 2
+    b = (b.pow 2) mod m
+
+var
+  a = initBigInt("2988348162058574136915891421498819466320163312926952423791023078876139")
+  b = initBigInt("2351399303373464486466122544523690094744975233415544072992656881240319")
+
+echo powmod(a, b, 10.pow 40)

Task/Modular-exponentiation/Oforth/modular-exponentiation.oforth

@@ -0,0 +1,6 @@
+: powmod(base, exponent, modulus)
+   1 exponent dup ifZero: [ return ]
+    while ( dup 0 > ) [
+      dup isEven ifFalse: [ swap base * modulus mod swap ]
+      2 / base sq modulus mod ->base
+      ] drop ;

Task/Modular-exponentiation/Sidef/modular-exponentiation-1.sidef

@@ -0,0 +1,4 @@
+say expmod(
+    2988348162058574136915891421498819466320163312926952423791023078876139,
+    2351399303373464486466122544523690094744975233415544072992656881240319,
+    10**40)

Task/Modular-exponentiation/Sidef/modular-exponentiation-2.sidef

@@ -0,0 +1,8 @@
+func expmod(a, b, n) {
+    var c = 1
+    do {
+        (c *= a) %= n if b.is_odd
+        (a *= a) %= n
+    } while (b //= 2)
+    c
+}